Luminous Landscape Forum

Equipment & Techniques => Medium Format / Film / Digital Backs – and Large Sensor Photography => Topic started by: timparkin on October 26, 2011, 10:13:48 am

Title: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 26, 2011, 10:13:48 am
Hi folks, I've been working with a few photographers and engineers to organise a big camera test (as part of a retest for the IQ180/8x10 article featured recently). We're comparing the results from an IQ180 on with Alpa WA/Digaron 40, Cambo/Digaron 35 & Phase 645/Digital 45mm shot in a studio (without flash but with daylight lighting booth). We had photographers who use both large format and MFDB's with us including a Phase One distributor to make sure the photographs were taken correctly. For the 8x10 and 4x5 shots I am happy with post processing these having scanned them on a Howtek 4500 (and checked the scans on a microscope and against a colleagues ICG 800dpi scanner) but I am interested in opinions on the optimal post processing for these files.

When I'm comparing the 80mp files against the 8x10 4000dpi scans (40,000 x 32,000) should I up rez them and how and also in terms of sharpening etc, do I let Capture One handle everything on auto (probably not) or do I just get a raw capture and use Photokit? etc, etc. We will be printing them as well but they will also obviously be displayed on screen for people to assess as most people won't be able to get to the 'show' we're hoping to give.

I'm basically trying to avoid people saying "well you should have used Thromboid zero point resharpening with the inconvoluted zeta prime transform four paraboids below sigma 6 criteria" (obviously people may not use these words exactly but I hope you get the idea).

We've also shot a scenic to get an idea of colour and real world use (it was a windy day on a cliff edge, just right to test the "you can't shoot 8x10 on a windy day" theory) and the P45+ (which we shot on a Linhof Techno with the 70mm Digaron WA) has a very different colour to the IQ180 (shot with an 80mm on a Phase 645 body). How would you normalise the colour? The IQ180 had a lot better colour in my opinion and tallied a lot closer with the Portra 400 and had a flavour of Velvia in there as well (at least you could get it looking at bit like Velvia which is near impossible with the P45+ as far as I could tell).

Any feedback or help is greatly appreciated..

Tim Parkin
http://www.timparkin.co.uk
http://www.landscapegb.com
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ctz on October 26, 2011, 11:20:36 am
great site (yours), tim!
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ErikKaffehr on October 26, 2011, 11:48:17 am
Hi,

Regarding color matching I'm pretty much in favor of using a color checker as a reference. Grey squares stay gray and have right lab values.

Regarding sharpening I'd suggest that you check http://www.luminous-landscape.com/essays/back-testing.shtml, Bill Atkinson describes the methods used.

Finally, I would establish a certain size of image, like 70x100 cm and a certain PPI like 360 and size all images to fit that size. You may need to sharpen a little bit after resize to compensate for sharpness lost in resizing.

I read your two of your articles and they were great!

Best regards
Erik


Hi folks, I've been working with a few photographers and engineers to organise a big camera test (as part of a retest for the IQ180/8x10 article featured recently). We're comparing the results from an IQ180 on with Alpa WA/Digaron 40, Cambo/Digaron 35 & Phase 645/Digital 45mm shot in a studio (without flash but with daylight lighting booth). We had photographers who use both large format and MFDB's with us including a Phase One distributor to make sure the photographs were taken correctly. For the 8x10 and 4x5 shots I am happy with post processing these having scanned them on a Howtek 4500 (and checked the scans on a microscope and against a colleagues ICG 800dpi scanner) but I am interested in opinions on the optimal post processing for these files.

When I'm comparing the 80mp files against the 8x10 4000dpi scans (40,000 x 32,000) should I up rez them and how and also in terms of sharpening etc, do I let Capture One handle everything on auto (probably not) or do I just get a raw capture and use Photokit? etc, etc. We will be printing them as well but they will also obviously be displayed on screen for people to assess as most people won't be able to get to the 'show' we're hoping to give.

I'm basically trying to avoid people saying "well you should have used Thromboid zero point resharpening with the inconvoluted zeta prime transform four paraboids below sigma 6 criteria" (obviously people may not use these words exactly but I hope you get the idea).

We've also shot a scenic to get an idea of colour and real world use (it was a windy day on a cliff edge, just right to test the "you can't shoot 8x10 on a windy day" theory) and the P45+ (which we shot on a Linhof Techno with the 70mm Digaron WA) has a very different colour to the IQ180 (shot with an 80mm on a Phase 645 body). How would you normalise the colour? The IQ180 had a lot better colour in my opinion and tallied a lot closer with the Portra 400 and had a flavour of Velvia in there as well (at least you could get it looking at bit like Velvia which is near impossible with the P45+ as far as I could tell).

Any feedback or help is greatly appreciated..

Tim Parkin
http://www.timparkin.co.uk
http://www.landscapegb.com
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Sheldon N on October 26, 2011, 12:58:18 pm
Personally, I would  not try to do too much to the digital shots to make them look like the film shots. I would display them with just basic white balance and normal tonal corrections. Everyone knows that digital starts out a lot more like a "blank slate" and that a lot can be done in post. I think people are more interested in real world resolution than digital vs film "rendition". If you wanted to do your own post processing on the digital landscape shot to show how the finished file would look, you could toss up a small jpeg showing how you might have rendered the image if you were working it up as part of your portfolio. That's more of a sidebar though, people want to see what the native files look like.

On how to display the film vs digital crops vs uprezzing/downsizing. I would make a value judgement about at what dpi you stop gaining real detail in the scan. In other words, if you view the scan at 50% enlargement (2000dpi) and see that all the resolvable detail is shown, and viewing at 100% only shows grain or blur, then I would slightly downsize the film scan using photoshop Bicubic sharper. So the baseline essentially becomes "This is all that there is to see on the film". If someone is a doubter, you can always show a crop of the original scan for reference.  

The reason I suggest slightly downsizing the film scan is because I've seen some comparisons where the film scan is so high resolution that you don't really see image detail anymore, just blur and film grain clumps. It makes it harder to compare A vs B when you're looking at those.

For the digital files, I would just keep it simple and use Photoshop bicubic enlarger to take them up to the same size as the film scan. Maybe a *little* sharpening to taste if needed, but the less complicated the better. Genuine Fractals would be another option for enlarging, if you have access to that.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 26, 2011, 05:54:20 pm
I agree to a point but a high contrast shot can look sharper than a low contrast shot - perhaps I should show the raw comparison and then normalise the luminosity at least for a second comparison.

I agree about not showing stupidly enlarged files but it's good to show what is being captured at full scan resolution (fortunately there is detail so it's not an issue).

I'll have a go at genuine fractals - sounds like a good idea.

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Jack Flesher on October 26, 2011, 09:36:40 pm
I'll save you the trouble, because here is the likely result:

1) If your processed IQ180 files look bad compared your processed 8x10 files, the digital folks will claim your digital processing was flawed, or that you didn't know how to optimally use the camera and/or lens and/or software.

2) If your processed 8x10 files look bad compared to your processed IQ180 files, the film folks will claim you used a bad camera or a bad lens, or bad technique, and/or had a bad lab process your film, and/or didn't know how to scan or the lab you used scanned poorly.

In short, you will spend a bunch of time and prove nothing except to yourself.  

And here is the bit that seals your fate: The fact you are already asking how to best process the Phase files does not bode well for the outcome...  

Sorry, but I am being realistic not pessimistic: It will be virtually impossible to perform the test in a manner that will satisfy both extremes, especially if you are not already a recognized expert in both 8x10 capture and scanning as well as an expert in digital processing using Capture 1.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Fine_Art on October 26, 2011, 09:59:09 pm
If its a 4000dpi scan that shows good focus there is nothing to complain about. That is quite representative of what any user would try to extract.

If you have a Phase rep 'helping the digital shot no one can complain about that either.

Lets see a shot of both prints together in the same shot to look at the overall feel of the picture. If someone doesnt like that they dont have to look.
Lets see crops of focused detail at 50%, 100% resolution.
Present what both are good at such as the smooth highlight shoulder of film; the dark details of digital.

Please, and thank you for taking the time to share it.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: EricWHiss on October 26, 2011, 11:51:14 pm
Thank you for redoing the comparison and I look forward to seeing your results.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ErikKaffehr on October 26, 2011, 11:53:30 pm
+1

Erik

Thank you for redoing the comparison and I look forward to seeing your results.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ErikKaffehr on October 27, 2011, 12:09:34 am
Hi,

Tim scans at 4000PPI. Now, 4000PPI will give something like a 40k/30k pixel image. To match that size the IQ180 would need to be blown up almost five times linear.

I have looked at a 67 Velvia scan at 6000 PPI. Downsizing it to 3000 PPI and upsizing it I could not see any difference. Doing the same exercise to 2000 PPI and back the difference was clear. So I'd say that Tim's approach of scanning at 4000 PPI is reasonable.

What looks most reasonable to me is to:

1) Make a basic conversion of the IQ180 image using default settings in C1
2) Upres to 2000 PPI and sharpen to taste
3) Downres 8x10" image to 2000PPI and sharpen to taste
4) Analyze and draw conclusions
5) Upres IQ180 image from original to match 8x10", sharpen to taste
6) Analyze and draw conclusions

I'd assume that there will be no clear winner/looser. Digital has advantages in some areas, noise, sharpening, handling of low contrast detail. Analogue has some benefits of it's own, but they may be harder to demonstrate. Negative film will definitively handle specular highlights better than digital but may lack in other areas. They are different animals.

Best regards
Erik


I'll save you the trouble, because here is the likely result:

1) If your processed IQ180 files look bad compared your processed 8x10 files, the digital folks will claim your digital processing was flawed, or that you didn't know how to optimally use the camera and/or lens and/or software.

2) If your processed 8x10 files look bad compared to your processed IQ180 files, the film folks will claim you used a bad camera or a bad lens, or bad technique, and/or had a bad lab process your film, and/or didn't know how to scan or the lab you used scanned poorly.

In short, you will spend a bunch of time and prove nothing except to yourself.  

And here is the bit that seals your fate: The fact you are already asking how to best process the Phase files does not bode well for the outcome...  

Sorry, but I am being realistic not pessimistic: It will be virtually impossible to perform the test in a manner that will satisfy both extremes, especially if you are not already a recognized expert in both 8x10 capture and scanning as well as an expert in digital processing using Capture 1.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Jack Flesher on October 27, 2011, 12:41:22 am
Guys, I would love to be proved wrong about how the results from this test will play out. So show me :D



Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 04:06:35 am
I'm a bit dissapointed in that response to be honest Jack. Here are a few details of the test:

I'm working with Joe Cornish who is one of Europe's top landscape photographers and has been working with Phase and Capture One for a few years and I have also had the CEO of Direct Digital Imaging (DDI) operate and attend the photoshoot and also spent a morning with me post processing the files. I also use Capture One to process my DSLR files so am hardly unfamiliar.

I am not asking advice how to use Capture One, I'm asking advice on how people approach the post processing of files. As there is no right or wrong in post processing, I was canvassing opinion so I can try a few different methods to see which may work better. For instance, I'm also talking to Julian Calverly (IQ180 owner) who has a different post processing approach to Chris Ireland (DDI).

As for your points

1) The IQ180 files look bad.

Well if we can't get a good IQ180 file with a professional user and a CEO of a company that sells Phase products in the room using Alpa, Cambo & Phase gear with the best Schneider and Rodenstock glass and with the files post processed by said CEO and checked by said professional I think there is a problem with the camera/software?

2) The 8x10 files look bad

Again, we had three large format photographers in the room and have solicited opinion in advance on how the test should be run, including small variations in focus, multiple shots to discount vibration, film sag, taped film and three different makes of holder to double check (Toyo, Fidelity and Chamonix). We also had the camera mounted on a 5 series gitzo with a second 3 series gitzo supporting the front and used Fujinion 240A and APO Symmar 360 lenses at a range of apertures.

The film was dev'd by Peak Imaging but I held back a couple of shots to dev myself and confirmed that the results were consistent.

The film is being checked on a microscope (to which I can attach a camera) and has been scanned on a Howtek 4500 with a backup scan done on a Fuji Lanovia and an 8000dpi ICG. I am also getting a third opinion from a pro scanner in the US (Lenny Eiger). Three scans should be enough I think.

Personally I don't care how many people complain about the test - at least there is one being done rather than just a lot of hot air being bandied about.

As for 'spending a bunch of time proving nothing except to myself' - strangely I've had so much interest in this that I have had people offering money to help support the test and have had companies lending software, services and equipment with an insurance value nudging a quarter of a million dollars.

You are a bright guy Jack, I was really hoping to get a useful response.

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Graham Mitchell on October 27, 2011, 04:42:11 am
I'm looking forward to seeing the results.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ced on October 27, 2011, 04:51:56 am
First of all thanks for going through the trouble of tackling such a test.
I would not do any sharpening, let the person looking at them do his own "magic".
Choose a very good area with details and contrast and crop that area to be downloaded as a 16bit tiff but that the files have exactly the same end points and mid tone value, do not try to colour correct, there the voodooists can perform their own dance.
Give us your conclusions with the help from the specialists that helped and let the reader draw his/her own conclusions and try to prove otherwise themselves.
Make the raw files available to download and do not respond to any critic only to positive comments.
If you have used the "best" available to you, there is not much more that can be expected.
You are entering stormy waters, look forward to seeing your effort and good luck with the project!

Title: Re: Post processing IQ180 files for resolution/camera test
Post by: yaya on October 27, 2011, 05:10:04 am
First of all thanks for going through the trouble of tackling such a test.
I would not do any sharpening, let the person looking at them do his own "magic".
Choose a very good area with details and contrast and crop that area to be downloaded as a 16bit tiff but that the files have exactly the same end points and mid tone value, do not try to colour correct, there the voodooists can perform their own dance.
Give us your conclusions with the help from the specialists that helped and let the reader draw his/her own conclusions and try to prove otherwise themselves.
Make the raw files available to download and do not respond to any critic only to positive comments.
If you have used the "best" available to you, there is not much more that can be expected.
You are entering stormy waters, look forward to seeing your effort and good luck with the project!



My thoughts exactly!

Thanks for taking the time to do this test Tim. If you feel like getting some Leaf image quality and Leaf Capture "magic" in the mix just give me a shout:-)

Yair
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 05:13:54 am
First of all thanks for going through the trouble of tackling such a test.
I would not do any sharpening, let the person looking at them do his own "magic".
Choose a very good area with details and contrast and crop that area to be downloaded as a 16bit tiff but that the files have exactly the same end points and mid tone value, do not try to colour correct, there the voodooists can perform their own dance.
Give us your conclusions with the help from the specialists that helped and let the reader draw his/her own conclusions and try to prove otherwise themselves.
Make the raw files available to download and do not respond to any critic only to positive comments.
If you have used the "best" available to you, there is not much more that can be expected.
You are entering stormy waters, look forward to seeing your effort and good luck with the project!

Thanks CED - I'll definitely do this as a baseline but I think I'll also apply our combined voodoo for people who don't have the skills or haven't the time. The obvious conclusion will be "they're all different cameras" :-)

As for stormy waters, I've been there before when redesigning a website for one of the biggest programming communities online. Trying to get the concept of design and marketing across to open source software developers created some extreme comments stopping just short of death threats :-) If I can cope with that I can cope with a few online naysayers and ner do wells - as you say the best tactic is to ignore them. If people are being critical constructively, I'm happy to engage though.

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 05:15:36 am
My thoughts exactly!  Thanks for taking the time to do this test Tim. If you feel like getting some Leaf image quality and Leaf Capture "magic" in the mix just give me a shout:-)     --   Yair

Thanks - I don't suppose you are in the UK are you? Might be a bit difficult if not.. I woudn't know who to approach in the UK regarding Leaf.. I should add that we're going to be running a comparison of the IQ180 vs P45+ on the Linhof Techno hopefully as well, just to see what the differences are. From what I've seen so far, the colour from the IQ180 is very nice and a lot better than the P45.

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: yaya on October 27, 2011, 05:29:50 am
Thanks - I don't suppose you are in the UK are you? Might be a bit difficult if not.. I woudn't know who to approach in the UK regarding Leaf.. I should add that we're going to be running a comparison of the IQ180 vs P45+ on the Linhof Techno hopefully as well, just to see what the differences are. From what I've seen so far, the colour from the IQ180 is very nice and a lot better than the P45.

Tim

I'm in London...we have 3 UK dealers plus a regional sales manager who takes care of Phase One, Leaf and Mamiya

BR Yair
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: marcmccalmont on October 27, 2011, 08:29:42 am
I'm more with Jack, who cares? apples and oranges will the IQ240 be compared to 16x20 film of course not!
Excellent results from 4x5 film and excellent results from an IQ180 (with a technical camera!)
I'm so happy with my IQ180 and my Rodenstock HR lenses, that's all that counts.
Remember Film has had 100 years or more to mature, at best digital in in it's adolescence.
I can always stitch and HDR if I need more.
Marc
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 08:45:16 am
I'm more with Jack, who cares? apples and oranges will the IQ240 be compared to 16x20 film of course not!
Excellent results from 4x5 film and excellent results from an IQ180 (with a technical camera!)
I'm so happy with my IQ180 and my Rodenstock HR lenses, that's all that counts.
Remember Film has had 100 years or more to mature, at best digital in in it's adolescence.
I can always stitch and HDR if I need more.
Marc

So that would be a "No, I don't have any recommendations" then? :-)

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 08:49:20 am
I'm in London...we have 3 UK dealers plus a regional sales manager who takes care of Phase One, Leaf and Mamiya

BR Yair

I which case I could be very interested :-) If you want to email me, my address is on timparkin.co.uk

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Bart_van_der_Wolf on October 27, 2011, 10:42:38 am
Hi folks, I've been working with a few photographers and engineers to organise a big camera test (as part of a retest for the IQ180/8x10 article featured recently). We're comparing the results from an IQ180 on with Alpa WA/Digaron 40, Cambo/Digaron 35 & Phase 645/Digital 45mm shot in a studio (without flash but with daylight lighting booth). We had photographers who use both large format and MFDB's with us including a Phase One distributor to make sure the photographs were taken correctly. For the 8x10 and 4x5 shots I am happy with post processing these having scanned them on a Howtek 4500 (and checked the scans on a microscope and against a colleagues ICG 800dpi scanner) but I am interested in opinions on the optimal post processing for these files.

Hi Tim,

I'm already looking forward to the results, as it seems to be a well managed and executed process done by openminded people who know what they're doing.

Quote
When I'm comparing the 80mp files against the 8x10 4000dpi scans (40,000 x 32,000) should I up rez them and how and also in terms of sharpening etc, do I let Capture One handle everything on auto (probably not) or do I just get a raw capture and use Photokit? etc, etc. We will be printing them as well but they will also obviously be displayed on screen for people to assess as most people won't be able to get to the 'show' we're hoping to give.

There are IMHO 2 aspects to a good film scan. The first is to extract all resolution, and second to minimize the distraction from graininess, and there is a trade-off between those parameters. In practice it means having to scan the film with something like 6000+ PPI by a competent operator who can balance the scanning aperture size with the grain/dye cloud structure. Smaller scans will perhaps not extract all detail, and increase the grain-aliasing effect.

It would therefore be useful to separately determine (and thus demonstrate) what the limiting resolution of a chosen system approach is. With system approach I mean camera system, film, and scanner, their combined MTF in understandable terms. There is a number of methods that could be used to quantify a few simple parameters that everybody can understand, complemented by visual confirmation.

I'm hinting at an Edge Spread Function (ESF) such as reported by the Imatest software as Edge response (http://www.imatest.com/docs/sfr_MTFplot.html) (1/3rd down the page), and based on a simple slanted edge that you can print yourself. There is also a slanted edge in my target which spawned a discussion here (http://www.luminous-landscape.com/forum/index.php?topic=58661.0) on LuLa, and it also easily allows to confirm correct focus. There is a number of LuLa forum contributors who could assist in producing that part of the data, myself included. The method also allows to detect sharpening artifacts such as halo. Since it quantifies a phenomenon in the spatial domain (pixels) it is not difficult to imagine such an edge even without knowledge of how to read MTF curves.

I think resampling would be quite acceptable for all viewers if the up/down sampling operation results in similar looking sharpness (the edge acutance and artifacts balance) if the systems were equally sharp. The only difference that then remains is the actual resolution differences, decoupled from the resampling method. So the resampling method should not introduce a new bias, but that may prove to be trickier than anticipated (e.g. Photoshop is pretty poor at downsampling without introducing artifacts).

The most neutral comparison is therefore to offer both, an upsample of the smaller sensor to the film scan PPI (the only variable introduced is the choice of upsampling algorithm for one of the sources, more about that later), and a downsample to the smaller output size (with the only variable introduced being the downsample algorithm used for the other source). That allows to only have a single variable added to one element of the mix, but both sides of the user spectrum (large output vs smaller output) can draw their own conclusions.

Quote
I'm basically trying to avoid people saying "well you should have used Thromboid zero point resharpening with the inconvoluted zeta prime transform four paraboids below sigma 6 criteria" (obviously people may not use these words exactly but I hope you get the idea).


Exactly. Nobody can relate their own workflow to such a theoretically potential quality level, especially when it's only achievable under restrictive laboratory conditions, and depends on the phase of the moon. We all marvel at what rocket science brings, but we if we cannot afford or use it, it's only of theoretical interest.

However, that doesn't mean that lowest common denominator approaches are very informative either, because they introduce distracting artifacts. One could, as reasonable compromise, use resampling methods that are industry proven (e.g. such as implemented in ImageMagick). That will also avoid having to use commercial proprietary resampling algorithms, which may cut some corners for speed, or depends on other settings,  while hoping to hide the shortcomings for the uneducated public. The algorithms used by ImageMagick are publicly available and documented, and since the software is free, tests can be independently duplicated with the same results.

Quote
We've also shot a scenic to get an idea of colour and real world use (it was a windy day on a cliff edge, just right to test the "you can't shoot 8x10 on a windy day" theory) and the P45+ (which we shot on a Linhof Techno with the 70mm Digaron WA) has a very different colour to the IQ180 (shot with an 80mm on a Phase 645 body). How would you normalise the colour? The IQ180 had a lot better colour in my opinion and tallied a lot closer with the Portra 400 and had a flavour of Velvia in there as well (at least you could get it looking at bit like Velvia which is near impossible with the P45+ as far as I could tell).

Color rendering and tonality differences are another hornet's nest. However, I do wonder how distractive the differences (after white balancing) are? You've seen them, and that perhaps raised the question. Do they appeal to someone's esthetic preference so much as to impede the ability to look past that quality and judge the other qualities?

Cheers,
Bart
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: nazdravanul on October 27, 2011, 02:10:34 pm
I'm also looking forward to this :) . Please include the Aptus 80 in the mix, if possible ....
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Fine_Art on October 27, 2011, 02:40:10 pm
Dont worry about film grain. At a proper resolution it can be wiped out just like noise.

This is a noise ninja of a Fuji 800 Press shot. That has huge grain.
(http://farm7.static.flickr.com/6093/6284888529_4b78f23227_b.jpg)
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Stefan.Steib on October 27, 2011, 04:10:23 pm
I'll save you the trouble, because here is the likely result:

1) If your processed IQ180 files look bad compared your processed 8x10 files, the digital folks will claim your digital processing was flawed, or that you didn't know how to optimally use the camera and/or lens and/or software.

2) If your processed 8x10 files look bad compared to your processed IQ180 files, the film folks will claim you used a bad camera or a bad lens, or bad technique, and/or had a bad lab process your film, and/or didn't know how to scan or the lab you used scanned poorly.

In short, you will spend a bunch of time and prove nothing except to yourself.  

And here is the bit that seals your fate: The fact you are already asking how to best process the Phase files does not bode well for the outcome...  

Sorry, but I am being realistic not pessimistic: It will be virtually impossible to perform the test in a manner that will satisfy both extremes, especially if you are not already a recognized expert in both 8x10 capture and scanning as well as an expert in digital processing using Capture 1.

Jack - wisely spoken, but I think it´s not getting to the minds of the participants here.
I still wonder how much time and effort some of you have to perform this kind of tests.

To me it is out of question that both approaches can result in stunning photographs that stand for their own.
It is also clear that film can do things that Digital cannot (yet) do and vice versa Digital has immediate access and other advantages that film does not have.

I understand that this is a technical forum, but as Jack already said: no matter what you will test - it will proof nothing or anything that anyone wants to hear or not to hear.

So the question here is what is the motivation?
Is there anything likely to be expected or a chance to expect the unexpected ?
 ???

I know you guys will do it anyway. Have fun !   :)

Greetings from Munich
Stefan
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: marcmccalmont on October 27, 2011, 04:13:51 pm
I would test an IQ180 with an excellent lens (rodenstock 70HR) mounted on a technical camera to 8X10 using an equally good lens for the test
The lenses are the limiting factor with the IQ180
Marc
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Fine_Art on October 27, 2011, 04:19:00 pm
Of course the film has to be a fine ISO 100 or less. Provia, Velvia and an Ektar for negative seems appropriate.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Graham Mitchell on October 27, 2011, 04:36:47 pm
I would test an IQ180 with an excellent lens (rodenstock 70HR) mounted on a technical camera to 8X10 using an equally good lens for the test
The lenses are the limiting factor with the IQ180
Marc

Good point.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 05:06:51 pm
So the question here is what is the motivation?

The motivation is to have one good test that addresses most of the concerns of both sides. Obviously some people don't want to know but I think they are vastly outnumbered that *are* interested. If you've already made up your mind then it's irrelevant however most people like to have some quality information about what the options are before they put down large sums of money. From my point of view I'm probably a rare person that has access to everything needed to do the tests and the time to do them because I run a magazine about landscape photography and I think it may be something our readers will be interested in.

Fundamentally though, my motivation is "I want to know".. and if I can share that then all the better.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Fine_Art on October 27, 2011, 05:10:34 pm
Or why not to put down large sums of money!
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 05:11:35 pm
Hi Tim,

I'm already looking forward to the results, as it seems to be a well managed and executed process done by openminded people who know what they're doing.

...

Bart

Hi Bart - we've got an Imatest Master license and have shot a slanted edge target as well as a couple of general resolution 'trumpets' :-)

Out of interest, I'm not sure what downsizing the higher resolution result to the lower resolution result is supposed to acheive - it sounds like throwing away information? I can understand that you end up comparing contrast at the highest MTF of the lower resolution result - is this all?
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 05:24:12 pm
I would test an IQ180 with an excellent lens (rodenstock 70HR) mounted on a technical camera to 8X10 using an equally good lens for the test
The lenses are the limiting factor with the IQ180
Marc

We've used the 40 Digaron W, Schneider 35mm APO Digitar, Phase/Schneider 80mm f/2.8 and 70 Digaron W for the tests on Alpa WA, Cambo WRS, Linhof Techno and Phase 645 DF.

On the large format we shot a Toyo 810MII with a Fujinon 240A and APO Symmar 360.

The films used were Delta 100, Provia, Velvia, Portra 400 and Pro160S on the 10x8 - Delta 100, Provia, Portra400, Pro160S on the 5x4 - T-Max, Portra 400 on the 6x7 (we're shooting a Mamiya 7 with 55mm and 80mm lenses too).

The film is being assessed on a 100x stereo microscope and scanned on various scanners (including 8000dpi ICG and Aztek).

I'm very happy that the results are complementary to both systems though (i.e. they are both achieving near theoretical limits). There is still a lot to do before we publish though. We'll get something out at the end of November with commentary/analysis from various photographers and will be looking from considered feedback too.

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Mr. Rib on October 27, 2011, 06:36:27 pm
Thanks for your work Tim, eagerly waiting for the results!
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Stefan.Steib on October 27, 2011, 06:50:29 pm
Hi Tim

Understood - from this point it absolutely makes sense. It is giving you interesting content for your magazine.
It´s also a service for many people who want to read this.

Just 2 questions: is there something you expect to find out ?
And  - do I understand this right- this test will not be published here, but in your Magazine exclusively ?

Greetings from Munich
Stefan
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Schewe on October 27, 2011, 07:01:32 pm
Out of interest, I'm not sure what downsizing the higher resolution result to the lower resolution result is supposed to acheive - it sounds like throwing away information? I can understand that you end up comparing contrast at the highest MTF of the lower resolution result - is this all?

Part of the issue when comparing different formats and media is the context in which you are judging the images. If the purpose is pixel peeping, that's fine, but an 8x10 scan at 4000ppi is gonna be huge on screen vs an IQ180...so looking at 100% or even 50% zoom isn't very practical...

From my point of view, the final arbiter for me is a final print...a given print size as a reference point at a certain PPI might give a better context. This would require downsampling the scan and upsampling the IQ 180 (depending on the "print size" you choose) but would help give a context for how the different images sources would work in print. Of course, then you get into the printer, the media and trying to show a print in a web based environment....can be done but it's a different can of worms (or the same can with different worms :~)
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 07:16:40 pm
Hi Stefan,

Michael has offered to put the results up here but I imagine he will want to check them before he says yes. The results will also appear in the magazine for free and I'll be including additional content in the magazine (interviews with photographers about how they see the results, comparisons with DSLR's and medium format film cameras, essay about interpreting results and about why does it matter a damn in the first place, etc) some of which will be free, some free with subscription and the typically the longer essays and video/audio content is only available for paying subscribers. The key results regarding the 8x10 IQ180 comparison will be included for free on the magazine and will be available for Michael as well. We're hoping to get some commentary from some people who still use 10x8 and definitely will have some 4x5 and IQ180/P45+ users plus probably a few users of DSLRs and Medium Format film (we interviewed Jack Dykinga last week and he's an interesting example of someone who has moved from 4x5 to DSLR + tilt lenses.. )

As for something I expect to find out? Well I had my preconceptions that the IQ180 would out resolve 4x5 just but 10x8 would outresolve them both but not by the 2:1 ratio the increase in film size suggests. I also expected the results to appear very different and be quite intriguing to interpret (i.e. depending on what you look at the the 4x5 may end up outresolving the IQ180). I also expected to see some effects of the bayer algorithm come into play along with some low resolution results from film in the lower contrast parts of scenes.

However, I've got the first results back and I have to say I'm surprised by a few of the findings - more about that later of course :-) I know it's going to be 'controversial' but having engaged with both medium format digital back community and the large format community in advance, there shouldn't be too much to 'rationally' complain about from either side. Obviously there will be some small issues, it would have been nice to have a Sironar S 360 but I think the APO Symmar is probably outresolving the film anyway. I would have liked to have used a 240 Sironar S but the Fujinon has performed very well in some large group shots I had taken previously.

The one thing I would have liked to have done is to compare the IQ180 with the 10x8 with movements - however, so many people are using the Alpas and Cambos that it seems a fair test. We will definitely be putting the Linhof Techno + IQ180 up alongside the same Linhof and a P45+ and also an Ebony 45SU/180 Sironar S as part of a second test (my colleague Joe Cornish would like to find out the differences both in terms of resolution and aesthetics, as would I for that matter).  

Tim
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: timparkin on October 27, 2011, 07:25:51 pm
Part of the issue when comparing different formats and media is the context in which you are judging the images. If the purpose is pixel peeping, that's fine, but an 8x10 scan at 4000ppi is gonna be huge on screen vs an IQ180...so looking at 100% or even 50% zoom isn't very practical...

From my point of view, the final arbiter for me is a final print...a given print size as a reference point at a certain PPI might give a better context. This would require downsampling the scan and upsampling the IQ 180 (depending on the "print size" you choose) but would help give a context for how the different images sources would work in print. Of course, then you get into the printer, the media and trying to show a print in a web based environment....can be done but it's a different can of worms (or the same can with different worms :~)

Hence the comment in the first post of the thread "We will be printing them as well but they will also obviously be displayed on screen for people to assess as most people won't be able to get to the 'show' we're hoping to give.". In terms of showing them on screen, it is up to the viewer to decide at what 'level' they want to assess the results. I would suggest a 100% on screen and then step away from the screen to about 10ft - this is really the only way to emulate a 300dpi print on screen. Viewing at 50% is OK for an indication but it doesn't emulate the very fine detail that may appear in a print. Viewing at any less than 50% is pretty pointless unless you are testing what the file will look like when printed well below it's maximum resolution.

I'm looking forward to hopefully getting some darkroom prints made as well if possible.

Tim

Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Stefan.Steib on October 27, 2011, 07:54:12 pm
 :)  Tim

I admit this sounds like a lot of nice toys................
Ok - I am interested too....

greetings from Munich

Stefan
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Sheldon N on October 27, 2011, 08:06:44 pm
Very interested to see the results of this. Looks to be an extremely well thought out and thorough test.

Thanks for taking the time!
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Jack Flesher on October 27, 2011, 08:23:18 pm
I'm a bit dissapointed in that response to be honest Jack.
SNIP
You are a bright guy Jack, I was really hoping to get a useful response.

Tim

Tim,

Please understand I am not bashing you, your test or your method! I am simply stating that I believe regardless of whatever result you end up with, and no matter how well you controlled variables,  you are going to hear from folks on the "losing" side that are going to claim you did something wrong or did not do something you should have when capturing or processing their preferred medium.

You want helpful info, then here are a few basic questions to help start your thinking about some of the issues I see:

1) What aperture will you shoot the 40 HR-W and/or 70 HR-W at? (Optimal is probably ~ f8-11 for both.)
2) What aperture will you shoot the 240 Fujinon and/or 360 APO Sym 360 at? (Optimal is probably ~ f22-32 for both)
3) Assuming you will be photographing the same subjects from the same shooting distances with both systems, and assuming you will confirm precise focus with each before utilizing the image, how will you reconcile the differences in DoF between the 2 formats? (f8 on the 70 would require roughly an absurd f256 on the 360 for equivalent DoF at the same CoC's. However if you use 10x the CoC for the 8x10, then f8 on the IQ should be roughly equivalent to f32 on the 8x10.)
4) The 40 HR is roughly equivalent to a 180 on the 8x10, but you don't have a 180 for the 8x10 -- how do you plan to compare the 240 Fuji to the wider 40HR on MF?
5) The 70 HR is roughly comparable to a 300 on 8x10, but you don't have a 300, again, how do you plan on reconciling that subject magnification difference with your 360?
6) The 40 HR is outstanding and about "as good as it gets" for digital and has slightly higher resolution than the 70 HR (I currently own them both). The 360 APO symmar is outstanding or "as good as it gets" on 8x10, and better than the 240 Fuji (yes, when I shot 8x10 I owned both of those lenses too). So if you used the best of your list on each system, how do you reconcile the now more extreme FoV/magnification differences?

    
So I will submit that: Assuming you can somehow get to equivalent FoV's AND rectify DoF differences while using each system at optimal resolution apertures for each piece of glass (non-trivial to be sure), and assuming you can perfectly capture (relatively easy for the IQ, non-trivial for 8x10), AND perfectly process out each file to final digital file (a relatively easy step for direct digital if you do everything well at capture; more complex steps involved in getting the film processed and scanned, but certainly doable), then get those to as perfect as possible digital prints (relatively easy if you know what you're doing), AND then get as perfect as possible optical print from the 8x10 neg/tranny (non-trivial unless you have a truly stellar wet lab at your disposal) to compare, I think you will have a done an incredible service to the photographic community!  And I will even treat you to a steak dinner and fine bottle of wine to congratulate you :)

But... I still believe regardless of all of the above efforts, you will hear cries of "foul" from supporters of both sides regardless of how well you contain and control every aspect of your test.

Seriously, I wish you good luck and am happy to help in any way I can -- which at this point in time would be examination, processing and discussion of the IQ180 raw files, review of the final 8x10 scan file for comparative comment, and/or printing sections of each digital file for comparative review and comment of the respective (digital) prints.

Best,
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: theguywitha645d on October 27, 2011, 10:20:49 pm
Here is a crazy idea. Print the both images at say 20x30 inches and then scan the same area of the prints. That way each image will be normalized to a real condition and you do not need to up rez or down rez the files. That way you can have a direct comparison in an actual condition these files would be viewed without the need to touch the file data.

Jack is right though. Whoever believes that they have lost will point to an insignificant detail to "prove" the test is "false." But it would be nice to see.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ErikKaffehr on October 27, 2011, 10:48:03 pm
Hi,

There are two advantages of scaling down.

1) Scaling moves around pixels, so if we scale one image but not the other the image that is not scaled would be at advantage.

2) Scaling up the digital image 5X linear will introduce artifacts so the image will be ugly

The way I used to think is: Let's assume we make a print of size so and so at that PPI and rescale the images to achieve that PPI. Differences on screen will be much larger than on print.

Using Imatest on the slanted edge is in my view a good idea. One problem with Imatest is that it is sensitive to sharpening, and sharpening is an essential part of the digital workflow.

Best regards
Erik

Hi Bart - we've got an Imatest Master license and have shot a slanted edge target as well as a couple of general resolution 'trumpets' :-)

Out of interest, I'm not sure what downsizing the higher resolution result to the lower resolution result is supposed to acheive - it sounds like throwing away information? I can understand that you end up comparing contrast at the highest MTF of the lower resolution result - is this all?
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Fine_Art on October 27, 2011, 11:08:41 pm
Here is a crazy idea. Print the both images at say 20x30 inches and then scan the same area of the prints. That way each image will be normalized to a real condition and you do not need to up rez or down rez the files. That way you can have a direct comparison in an actual condition these files would be viewed without the need to touch the file data.


I like that.


There is no point in scaling just to degrade the pixels. Given the formats a large print is required. Nobody would go through the trouble or the expense of these systems for a web shot. Like Schewe said, the quality of the print is what matters. If a 4000dpi scan gives you enough pixels that you don't need to upres then so be it, that is why 8x10 was chosen. Otherwise 4x5 or less would have been used.

These systems would be used for a gallery print. Lets see a comparison of a gallery print resolution.

Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ErikKaffehr on October 28, 2011, 12:14:54 am
Hi,

You can do an excellent 30x40" print from CCD scanned Velvia 67, or a 40 MP digital back. You need to print larger than that for 8x10" or 80MP to really come into play.

I have done something similar with images downloaded from Imaging Resource, here: http://echophoto.dnsalias.net/ekr/images/Pentax645D/A0_print_center.jpg

These prints correspond to A0 (ca 33.1x46.8"), the crops are scanned at 300PPI. Left D3X, LR "scenic scarpening" preset), mid D3X (LR, deconvolution), right Pentax 645D (LR, scenic).

Article is here: http://echophoto.dnsalias.net/ekr/index.php/photoarticles/51-a-closer-look-at-pentax-645d-image-quality

I'm fully aware that the things we are discussing now are in a different division than the Pentax or the Nikon, but physics and math still apply, and pixels are pixels.

Best regards
Erik

I like that.


There is no point in scaling just to degrade the pixels. Given the formats a large print is required. Nobody would go through the trouble or the expense of these systems for a web shot. Like Schewe said, the quality of the print is what matters. If a 4000dpi scan gives you enough pixels that you don't need to upres then so be it, that is why 8x10 was chosen. Otherwise 4x5 or less would have been used.

These systems would be used for a gallery print. Lets see a comparison of a gallery print resolution.


Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Fine_Art on October 28, 2011, 12:50:30 am
Print DPI should be 600 for cannon type or 720 epson, whatever an even scaling of the printer's default optimum.

Pixels be damned, let's not lose the plot. This is not about jumping through hoops for a test. This is about tools for impressive gallery prints. Both methods should be done with that in mind. Squeeze as much as possible from the method.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Stefan.Steib on October 28, 2011, 06:58:16 am
Tim

what Jack probably means is something that is called systemic noise in Chaos theory.
The more instances you need to get to a comparison of 2 values the more you will induce errors and variations caused by these additional steps.
A system (left alone 2 systems !) cannot be calibrated by some normalization as the measurement device itself induces new errors.
In this case there are 2 totally differing media which cannot be compared by numbers in their primary output (File against slide).
To get these both informations into the same system of comparable data you will definitely induce additional variation - this is "per definitionem".
Thus the Test is only "valid" if everybody will agree about the method, which as you can already see is "difficult".........

I agree that it is an interesting subject, but the approach is probably only possible if judged on a final product (maybe Print).
But this does not necessarily tell anything about the original material or it´s content of information which is the title here.
Maybe you should rename the task in : "What produces better prints at the actual status of technology Analogue or digital ?"
This would be a definition that is much clearer and can be judged in a definite and objective way.

Greetings from Munich
Stefan
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: hjulenissen on October 28, 2011, 07:04:52 am
There are IMHO 2 aspects to a good film scan. The first is to extract all resolution, and second to minimize the distraction from graininess, and there is a trade-off between those parameters. In practice it means having to scan the film with something like 6000+ PPI by a competent operator who can balance the scanning aperture size with the grain/dye cloud structure. Smaller scans will perhaps not extract all detail, and increase the grain-aliasing effect.
I dont do scans. But why would you want to do grain-suppression in the scanning process? Why not scan the image as accurately as possible (grain and all), then do grain removal in software?
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Bart_van_der_Wolf on October 28, 2011, 08:13:56 am
I dont do scans. But why would you want to do grain-suppression in the scanning process? Why not scan the image as accurately as possible (grain and all), then do grain removal in software?

Hi h,

It's not something like noise reduction, which we can additionally apply to the resulting file with software. It's more about not 'enhancing' the grain-structure (http://www.photoscientia.co.uk/Grain.htm), or slightly reducing the micro contrast at the grain/dye cloud level. It takes many grains/dye clouds in 3D to form visible granularity. A drumscanner has (on top of the high resolution which also reduces grain-aliasing) the added benefit of being able to vary the scanning aperture, which can be tuned to optimize detail contrast versus grain/dye cloud contrast.

Cheers,
Bart
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: hjulenissen on October 28, 2011, 08:48:01 am
Hi h,

It's not something like noise reduction, which we can additionally apply to the resulting file with software. It's more about not 'enhancing' the grain-structure (http://www.photoscientia.co.uk/Grain.htm), or slightly reducing the micro contrast at the grain/dye cloud level. It takes many grains/dye clouds in 3D to form visible granularity. A drumscanner has (on top of the high resolution which also reduces grain-aliasing) the added benefit of being able to vary the scanning aperture, which can be tuned to optimize detail contrast versus grain/dye cloud contrast.

Cheers,
Bart
But if you could obtain a Nyquistian filtered, sharp scanning at _any_ dpi, would you still prefer to filter out grain in the scanning, or doing it with some software?

-h
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Bart_van_der_Wolf on October 28, 2011, 08:51:30 am
Hi Bart - we've got an Imatest Master license and have shot a slanted edge target as well as a couple of general resolution 'trumpets' :-)

Hi Tim, there you go. I knew you guys had a grip on what you are doing ...

Quote
Out of interest, I'm not sure what downsizing the higher resolution result to the lower resolution result is supposed to acheive - it sounds like throwing away information? I can understand that you end up comparing contrast at the highest MTF of the lower resolution result - is this all?

Indeed, comparing 2 MTF curves at 2 different points is one. The outcome is not that easy to predict due to the differences in shape of the curves, especially due to the size difference of the 'sensors'.

I was also thinking about the psychological point of view of a MFDB shooter, who is accustomed to his/her reference, but less so to an upsampled version (only to match a deliberately oversampled filmscan). So by downsampling the filmscan, the familiar reference remains constant, and the unfamiliar rendering can get changed to match the size. A similar reasoning applies to those who are accustomed to large format oversampled scans, they will feel less comfortable with a significantly downsampled version (with risk of enhancing graininess) so the original scan should be the unchanged reference.

As for other suggestions along the line of printing to an identical size and scanning the result, it has it's use, but also adds another variable to the mix which might muddy the waters. Not everybody is equally good at producing large format output, and where e.g. a MFDB might benefit from adding noise, a filmscan might benefit from removing some graininess. It will be very difficult to satisfy all takers. Besides, what is large format for some, is a tad on the small side for others, so what would the output size of choice have to be?

Hence my suggestion for offering both up- and downsampling, and then people can do their own output test, based on their skills and available output modalities from that base material.

Cheers,
Bart
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Bart_van_der_Wolf on October 28, 2011, 08:55:07 am
But if you could obtain a Nyquistian filtered, sharp scanning at _any_ dpi, would you still prefer to filter out grain in the scanning, or doing it with some software?

Probably at the scanning stage, although it depends on the grain/dye cloud structure. Software noise reduction is good at filtering out periodic noise of a few fixed spatial frequencies, not random aggregates of different size and color.

Cheers,
Bart
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: marcmccalmont on October 28, 2011, 09:24:27 am
Yes I agree that a large print is necessary
Marc
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: buckshot on October 28, 2011, 09:37:38 am
Tim - look forward to the test. I'm not a pixel peeper per se, but these sort of things always seem to appeal to the technical voyeur in me. Plus, it's fun to see how hot around the collar some folks get at the thought their $40k digital back is about to get trumped by a piece of gelatin covered polyester.

One thing its worth thinking about is just the general 'look' of the images from an aesthetic point of view (subjective? hell, yes). Just step back from the computer and look at the printed images. To me the beauty of 8x10 and up is that certain 'look' of the images - dictated by the large size of the film, DoF, the glass used etc. etc. Medium format digital is just that - medium format - locked in a world of 6 x 4.5 cm for the foreseeable future.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: hjulenissen on October 28, 2011, 12:46:43 pm
Probably at the scanning stage, although it depends on the grain/dye cloud structure. Software noise reduction is good at filtering out periodic noise of a few fixed spatial frequencies, not random aggregates of different size and color.

Cheers,
Bart
What triggers my curiosity is: what kind of linear/nonlinear desirable operation is it that a scanner does when its resolution is decreased that me or you cannot emulate in an Excel spreadsheet that can be written in an hour?

Of course, there are practical considerations. Scanning at 10000 dpi will take longer time and demand more intermediate storage than 2000 dpi, and if the image contains practically no usable information in those spatial frequencies, it can be hard to defend. Same as taking pictures in raw does not add that much information to shooting in jpeg or sRaw/mRaw, but it does add flexibility in processing. If one is to do home-brew image processing using Excel it is going to be slow.

-h
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Bart_van_der_Wolf on October 28, 2011, 01:16:14 pm
What triggers my curiosity is: what kind of linear/nonlinear desirable operation is it that a scanner does when its resolution is decreased that me or you cannot emulate in an Excel spreadsheet that can be written in an hour?

Depends on one's Excel skills, but aliasing and sampling with an aperture is similar to what happens in a CCD or CMOS photovoltaic sensor (which has fixed apertures roughly the size of a sensel for each sensel). The main difference is that a drumscanner can vary the scanning aperture (and therefore samples the amount of a point sample all the way to an aperture driven moving averaging of larger areas, even overlapping) and the sampling position is controlled in an almost analog fashion, the film rotates in front of the analog photomultiplier.

Quote
Of course, there are practical considerations. Scanning at 10000 dpi will take longer time and demand more intermediate storage than 2000 dpi, and if the image contains practically no usable information in those spatial frequencies, it can be hard to defend.

Oversampling a signal does have benefits for signal reconstruction, especially when the output needs to be blown up to a large size, but indeed file size is one of the drawbacks. Everything that doesn't need to be invented/interpolated for reconstruction, but is sampled directly from the original signal, is likely to be more accurate (within the limitations of the sensor accuracy, in this case film). Finding out whether the cost (time, storage, equipment, labor) is balanced with the benefits, is part of the exercise.

Here's (http://www.cs.princeton.edu/courses/archive/spr06/cos426/papers/smith95b.pdf) a nice document to ponder about, and it also mentions scanning through an aperture, and the aperture's size and shape having an influence on the recorded signal.

But then, this thread is intended to be more about the presentation of a resolution/camera test, than discussing the benefits/drawbacks of one of the components.

Cheers,
Bart
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: hjulenissen on October 28, 2011, 01:42:21 pm
Here's (http://www.cs.princeton.edu/courses/archive/spr06/cos426/papers/smith95b.pdf) a nice document to ponder about, and it also mentions scanning through an aperture, and the aperture's size and shape having an influence on the recorded signal.
A long document, where the issue is discussed in two sentences. From what I could read there, it would seem that the behaviour of a scanner operating at an intermediate resolution can be precisely emulated by using a scanner at very high resolution, and then doing a simple 2-d gaussian filtered downsampler.

Let me know if I am hijacking this thread. I just thougth that optimally scanning/processing film would be relevant.

-h
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: theguywitha645d on October 28, 2011, 01:43:08 pm
You can actually print on 8x10 paper and simply scale the images to any size you want. The paper size is not a limiting factor to a print test--you don't need to print the whole image, just a section of it.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: ErikKaffehr on October 29, 2011, 01:21:58 am
Hi,

I don't think you are hijacking the thread. But I don't feel that this thread is about emulating scanning at lower resolution.

I have recently doing some comparisons between 6096 PPI scans and lower res CCD scans. One of the observations I have made is that CCD scans (say 3200 PPI) have more grain than the 6096 PPI drum scan. Also, the grain in the drum scan is quite nice. Downscaling and upscaling to say 2000 PPI and back will increase grain and make it more ugly.

One of the interesting observations was that there was a lot of grain in the original (Markus Zuber) test. The visibility of grain was interpreted as indication that all information has been resolved.

In my view, Bart makes a very good point. Digital photographers are used to see images with very well defined edges and essentially no noise. Hi res scans tend to be quite soft. Blowing up an MFDB image from 8000 pixels to 40000 pixels will introduce a lot of artificial detail.

The proposal to make prints is actually interesting, and crops can be printed and rescanned. This has the advantage that the whole processing pipeline is involved, including output sharpening, rescaling in printer driver, dithering. By choosing a correct scanning resolution we can even emulate eyesight.

My experience is that differences will be smaller on scanned prints than on screen at actual pixels.

This image is "actual pixels" view of detail on a comparison I made on 2003 vs 2010 version of LR:s processing pipeline:
http://echophoto.dnsalias.net/ekr/images/PVCompare/PV_compare_2003_vs_2010_sharpening.jpg

And this one is scanned at 300PPI from a 44x66 cm print:
http://echophoto.dnsalias.net/ekr/images/PVCompare/PV_2003_vs_2010_scan.jpg

Best regards
Erik


A long document, where the issue is discussed in two sentences. From what I could read there, it would seem that the behaviour of a scanner operating at an intermediate resolution can be precisely emulated by using a scanner at very high resolution, and then doing a simple 2-d gaussian filtered downsampler.

Let me know if I am hijacking this thread. I just thougth that optimally scanning/processing film would be relevant.

-h
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: harlemshooter on October 29, 2011, 04:11:21 am
A few comments:

1. Only artists are using large (and ultra) film formats in this day and age - and they aren't doing it to get maximal sharpness or to peep at crops. They are doing it for the artifacts introduced by the process (shallow depth of field, movements, etc) and for psychological or philosophical aspects of the slowed process itself. And most are not scanning the film to print other than for VERY large prints (try 8x10 feet with the IQ 180). Ain't gonna deliver, friend. Ask Thomas Struth. LOOK AT THE PRINT NOT THE 100% CROP if you want to get anything worthwhile whatsoever out of this so called "comparison".

2. Downsampling or upsampling either the IQ or film file is a good way to introduce undesirable junk. Why not just compare prints on actual paper at a size of 40x50 inches or larger? Are not LARGE PRINTS the entire point of high resolution image capture?

3. Look at a contact print from 8x10 (or larger) film (or a 2x optical enlargement). You can't obtain that smoothness digitally, never will. It is a result of millions of unique grain clumps scattered unpredictably within the depth of the emulsion.

4. This is a test for the pixel peepers of the universe, period.

5. This test is the equivalent of trying to use a banana peel as a baseball mitt. Films remarkable positive attributes mostly dissipate with digitization - even in huge prints in my opinion, although Jeff Wall (massive prints comprised of many stitched 4x5 transparencies) will disagree with me here: http://www.moma.org/interactives/exhibitions/2007/jeffwall/

Title: Re: Post processing IQ180 files for resolution/camera test
Post by: torger on October 30, 2011, 09:07:14 am
What is best will depend on the intended application.

I think it is important that a print looks good at *any* viewing distance, even if your nose is touching the print. It is however less important that it looks *sharp* at any viewing distance, that is it may not be important that the print outresolves the resolution of the eye.

Analog prints up close is a bit like paintings. When you come close you will on a painting see individual brush strokes, so you see it is a painting and although you don't see valid image detail it is a nice look. For an analog print you see grain so you see it is a photograph made on film, again you may not see much valid detail but the look is pleasing.

A digital image where you see pixelation, jaggies and aliasing when you come close is *not* nice. There's no romance to digital artifacts. Say if your digital file lets you keep the print resolution at 200 ppi or higher there will (generally) be no problem. But say if you will make a *huge* print so you get down to 10 ppi or so it will become more important that the file enlarges well than that it has the highest resolution.

Film enlarges well to any size. With digital, it is more complex. I have no experience from making huge prints, but I have made some experiments which indicate that if you want to make huge prints you should not have a super-sharp image at pixel peep level, that is AA filter or a bit of diffraction or outresolving the lens a bit is good. If you can see jaggies on pixel peep level you will get problems when enlarging. I've tested enlargement software but those spline-based scaling etc does not give a pleasing look, just artifical. The only thing that seems to enlarge well to huge sizes is a fairly soft original file (no jaggies) which is scaled up with simple scaling algorithms such as bicubic-soft.

I could imagine that IQ180 (lacks AA filter) with a very sharp lens will not look pleasing up close when enlarged to low ppi levels, and large format film would be much nicer, even if IQ180 might contain more actual detail. However if you don't need to print lower than say 200 ppi I think IQ180 will fare very well. I could also imagine that if you prepare the digital file well for huge enlargement you can make it look good up close, but you will have to prepare it differently (i e make sure it looks soft up close rather than maximizing detail for "normal" viewing distances so it becomes filled with digital artifacts up close) than you would for more moderate upsizing.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: theguywitha645d on October 30, 2011, 02:26:10 pm
A digital image where you see pixelation, jaggies and aliasing when you come close is *not* nice. There's no romance to digital artifacts. Say if your digital file lets you keep the print resolution at 200 ppi or higher there will (generally) be no problem. But say if you will make a *huge* print so you get down to 10 ppi or so it will become more important that the file enlarges well than that it has the highest resolution.

I can see you have not done too much large-format printing with digital files. The RIP and print drivers actually interpolate the file data so pixelation is avoided. There are no jaggies. It really is a myth that there is a limit to print size with digital files, just like folks used to claim there was a limit to film images depending on format size.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: hjulenissen on October 30, 2011, 02:44:19 pm
I can see you have not done too much large-format printing with digital files. The RIP and print drivers actually interpolate the file data so pixelation is avoided. There are no jaggies. It really is a myth that there is a limit to print size with digital files, just like folks used to claim there was a limit to film images depending on format size.
I havent done too much large-format printing with digital files. But if the image sensor/raw converter is doing nasty tricks to increase "perceived sharpness", I believe that it will be hard to get the image in a form that is suitable for scaling?

In principle I agree with you, though: if the image is sampled according to Nyquist (or close enough), then theory predicts that it can be scaled to any pixel grid using a simple linear filter with no artifacts (i.e. the image would appear more blurry the closer the viewer moves towards it).

-h
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: torger on October 30, 2011, 03:35:57 pm
I can see you have not done too much large-format printing with digital files. The RIP and print drivers actually interpolate the file data so pixelation is avoided. There are no jaggies. It really is a myth that there is a limit to print size with digital files, just like folks used to claim there was a limit to film images depending on format size.

I have printed under-resolution pictures though, although not billboard size :-). I also want my normal prints to look well under the loupe :-), so I am a little familiar with the problem. Printer drivers usually do something similar to bicubic-soft, and it will work well if your original image does not have too high pixel-to-pixel contrast, or if your end ppi is high.

Attached an image showing an example, upscaled with bicubic and viewed at 200% for clarity. The left picture is an upscaled version of a pixel-sharp original file, as it would look without AA-filter and sharp lens (and no heavy diffraction), the right is also upscaled and is based on a higher resolution original file, but with AA-filter and fairly soft at the pixel level. On the left you can see where the original pixels where around high contrast edges, while the right will not show that regardless of how much you upsize it since the original file is soft enough.

Exactly how soft a file needs to be to make pixels 100% invisible with bicubic upscaling can probably be calculated and defined mathematically (some maximum contrast level between neighbouring pixels). I know many digital systems are too sharp, especially if the file is sharpened before upscaling.

For more examples of what artifacts I mean you can look at http://www.benvista.com/photozoompro/examples they show upscaling of initially downscaled images and thus corresponds quite well to a system with very sharp lens and no AA-filter (although even such a system does not get *that* sharp, and there's demosaicing). Anyway, bicubic upscales has very clear artifacts and visible pixels. Those examples also show spline upscaling which hides pixelation but I think gives too artificial look and false detail. The best is to start off with a file which is soft enough at the pixel level so it can be upscaled bicubically to any size.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: torger on October 30, 2011, 03:56:34 pm
In principle I agree with you, though: if the image is sampled according to Nyquist (or close enough), then theory predicts that it can be scaled to any pixel grid using a simple linear filter with no artifacts (i.e. the image would appear more blurry the closer the viewer moves towards it).

In many digital systems, especially medium format (?) the resolving power of the lens etc is higher than of the sensor, so you can get aliasing moire etc. Some sensors have AA filters to reduce the resolving power to what the sensor can sample to avoid or minimize that problem. Generally, high res photographers dislike AA filters since they reduce contrast at pixel level, i e the percieved sharpness and detail becomes less when pixel-peeping. However, while such files are nice when printed at high PPIs, it seems to me that they do not enlarge well to billboard size if you want them to look pleasing up close (i e just soft rather than soft and pixelated).

Film does not have this problem.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: theguywitha645d on October 30, 2011, 08:03:07 pm
All I can say is I do not have your experience. I just made 7 foot prints from my 645D which has no AA filter and there is no pixelation. I also print 12 foot panoramas using the same camera, still no problems. If I made a billboard, the image would continue to look fine--you view them from cars after all.

Naturally, film image if optically printed start suffering at huge enlargements. You can digitize them, but then you are back to pixels.

Still, there is no limit to print size to either a film or a digital image. One is not better than the other.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: torger on October 31, 2011, 03:54:55 am
I was trying to explain why some has the experience that film enlarges better (like "harlemshooter"), and why if you scan film that you should use much higher resolution than the actual detail film has captured, for huge prints you want to reproduce the grain too.

However, your mileage will vary. How aliased or not a digital image will be depends on many factors, sensor pixel pitch, lens sharpness, aperture, focus, subject etc.

Here's an example of a Canon 5D without AA-filter to the left and with to the right.

http://www.maxmax.com/images/Cameras/Canon%205D/Comparison_3.jpg

I'd say that the left one is too aliased to enlarge well to huge sizes, but if printed at say 300 ppi in a book it will probably look better (apart from the moire) and sharper. An old 5D has 8.04 um pixel pitch though, which is not a tough challenge for lenses to render very sharp. More recent sensor with smaller pixel pitch will have less of a problem due to that the lenses (and possibly diffraction) will soften the image some. IQ180 has 5.17 um pixel pitch, together with lenses it probably will not render images as sharp-per-pixel as this 5D example, but probably sharper than the 5D with AA filter.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: BillOConnor on November 07, 2011, 11:22:28 pm
Can we talk about the realities of using an 8x10 view camera vs. the realities of using an MF camera with a digital back?
The 8x10 camera has such shallow depth of field, 325mm normal lens makes that a reality, that the photographer must choose his subject with great care. Swings and tilts only have limited effectiveness at 300mm and up, even at 150mm and up. The old shooters chose f64 because it leveled the focus field. The diffraction fuzzed the sharp areas so that they more closely matched the out of focus areas and the photographer relied on brute tone range to carry off the illusion that everything was mostly in focus.
Outdoors, wind was a brutal foe, a breeze not much less cruel. The film sagging in the holder helped a little because the curved piece of film more closely matched the curved field of focus of the lens, or not.
The equipment is brutally heavy, slow to set up, slow to use and completely impractical for magical times when the light is on the run.
Comparing the use of an 8x10 to the use of a MF camera with a digital back is a dilittante's folly. If you are comparing the ideal result in resolution from a scanned 8x10 transparency to the ideal result in resolution from an 80 megapixel back, you've achieved a result not even worth worrying about because the number of people shooting 8x10 sheet film will soon equal the number of people shooting 8x10 daguerreotypes.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Stefan.Steib on November 08, 2011, 04:04:52 am
>>>>>the number of people shooting 8x10 sheet film will soon equal the number of people shooting 8x10 daguerreotypes<<<<<<

Maybe even less..... Nobody knows what will happen if Kodak stops making sheet films. With only Fuji left and those also cutting down the Sheet film program this is only a matter of time until
also the Japanese will pull the plug. Kodak has sold the pearl of his digital assets now (which is not clever as I think - it´s probably only a desperate move to win time ) :

http://uk.reuters.com/article/2011/11/08/eastmankodak-idUKN1E7A61RD20111108?feedType=RSS&feedName=technology-media-telco-SP

and they are further looking into cutting non profit departments. They may gain some more time now to solve their problems, but I am sure sheet films are another victim to
streamlining their portfolio.
And what will be left over after this - a printer department which is just one among many and not very successful (with losses )......... ?

I wish them luck, Kodak has brought the world a lot of great inventions and I have worked with their products for a long time, but I fear they need more than luck.
They need a new concept and film is not part of this.

Greetings from Munich

Stefan

Title: Re: Post processing IQ180 files for resolution/camera test
Post by: Ben Rubinstein on November 08, 2011, 05:02:46 am
hehe, this is only the dust on the tip of the iceberg of what the responses will be like once the test is published :D

Tim, wishing you all the very best and the strength to ignore the flak.
Title: Re: Post processing IQ180 files for resolution/camera test
Post by: buldoozer on January 24, 2012, 08:38:49 am
Some years ago the global thingking was that you need 50MP to beat 4.5X6 ,200MP to beat 4X5 and 800MP to beat 8X10 format.A lot of thingking mistakes has been made at the time.The overal botleneck whit analog wed photography has always been the grain.The picture was captured on the grain so fine grain and negative size were importend.This is whit digital clearly not the case or bottleneck.Whit digital the picture is not captured on the sensor bud on the compactflashcard.The sensor works only as some sort of a transformer transforming fotons into electrons.Digital has no grain so al the problems which come whit it are gone.Thats means that sensorsize has nothing to do whit picturequality anymore.It has only to do whit how large you want to print the picture.The same goes for pixels.As long you cannot see the pixels on the final print whit your nose close to it,the resolution of digital is actualy infinity high.Thats why we now see in 2012 that digital prints are completly clean and sharp whit infiny high resolution because there is no grain at oll.As long as you keep the ISO low enough,you whont see noise too .I have razor sharp clean prints  from my 5D2 at 24X36 inch whit out pixelasation at 158DPI.You dont need 350DPI on a print to get a sharp print.350DPI was based on wed photography.Now in the end of the analog versus digital discusion whe see that 18MP is enough to beat 4.5X6, 40MP is enough to beat 4X5 and finaly 80MP is enough to beat 8X10 analog  negative format.Even the sensorsizes are away smaller than the big negatives that were needed in analog photgraphy.Bud how far does it go?. Sony has come whit a 24MP APS C format camera.Greating to you all from the Netherlands.