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Author Topic: Scan B&W photos/negs at 600 ppi. Is this best practice.  (Read 8006 times)

saiguy

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Scan B&W photos/negs at 600 ppi. Is this best practice.
« on: November 22, 2017, 08:41:35 PM »

I think I have read several times to scan B&W at 600 ppi. I always scan them in RGB mode. Read thru Mark Segal's SF8 book again but did not see any definitive mention on this.

What thoughts have you smart persons on this?
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Alskoj

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #1 on: November 22, 2017, 10:33:59 PM »

I think I have read several times to scan B&W at 600 ppi. I always scan them in RGB mode. Read thru Mark Segal's SF8 book again but did not see any definitive mention on this.

What thoughts have you smart persons on this?
Are you talking about a flat bed scanner (for prints) or drum scanner (for film)?
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TonyW

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #2 on: November 23, 2017, 05:36:49 AM »

I think I have read several times to scan B&W at 600 ppi. I always scan them in RGB mode. Read thru Mark Segal's SF8 book again but did not see any definitive mention on this.

What thoughts have you smart persons on this?
If you are scanning a good clean original B&W print then 600 should in most cases be quite adequate - it may also be that if the original contains a lot of detail that your scanner may be able to record this using a higher res. E.g. 1200 SPI.  You may want to experiment and see where your scanner limits are.

On the other hand if you are trying to restore an old damaged and stained print then scanning in RGB may offer benefits e.g. removing stains by using colour adjustments rather than cloning and patching.
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Mark D Segal

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #3 on: November 23, 2017, 07:32:50 AM »

I think I have read several times to scan B&W at 600 ppi. I always scan them in RGB mode. Read thru Mark Segal's SF8 book again but did not see any definitive mention on this.

What thoughts have you smart persons on this?

Chapter Five of my book covers this in considerable detail, and the same principles explained there apply whether scanning film or paper. The appropriate resolution depends on the relationship between the relative dimensions of the original versus largest scanned output you will ever want to retain and the number of pixels per inch you need for the output purpose (e.g. print or web viewing). It will be finally limited by the optical resolution of the scanner. Some people recommend scanning at the maximum "optical" resolution of the scanner (means resolution that isn't boosted by resampling in the software) so that you retain the maximum amount of highest quality information available without needing to rescan at some future date. Other people, me included, recommend scanning at a resolution that you think will meet your largest anticipated requirements. This may be less than the maximum optical resolution of the scanner. The purpose of this approach is to keep file sizes more closely aligned with need, but if you don't care about file size, go big.

Beware that if you are scanning a large original (for example flatbed scanning of a print), there are several things to think about before making a final choice of resolution: (1) what's the effective resolution of the original media you are scanning? Chances are it's no more than about 200~300 PPI equivalent, and no matter how many more PPI you scan it at, the process will not resolve more than it starts with (leaving aside deconvolution technologies). (2) Pixel dimensions grow very quickly because you are starting with a lot of inches, compared say with a 35mm slide or negative. You'll want to scan at a resolution which reproduces in the final output size at least the effective resolution of the original, but being mindful of file size bloat beyond what's needed for the purpose. I've provided formulae in the book for working all this out quite easily.
« Last Edit: November 23, 2017, 10:05:40 AM by Mark D Segal »
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Mark D Segal (formerly MarkDS)
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saiguy

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #4 on: November 23, 2017, 09:09:31 AM »

Thanks Alskoj,  No drum scans. Have Nikon LS 9000 and Epson Expression 11000 XL.

Thanks Mark,  Will read chapter 5 again.

Happy Thanksgiving
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Mark D Segal

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #5 on: November 23, 2017, 10:24:35 AM »

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Mark D Segal (formerly MarkDS)
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digitaldog

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #6 on: November 23, 2017, 11:59:22 AM »

I think I have read several times to scan B&W at 600 ppi. I always scan them in RGB mode. Read thru Mark Segal's SF8 book again but did not see any definitive mention on this.
What thoughts have you smart persons on this?
B&W, color; makes no difference. Scan at the highest optimal resolution if possible. Then you'll have all the data possible for all needs from that one scan. Now if you know for a fact you will only use less data once and never again, OK but never is a long time.
Scan once, use many. So maybe color since you can convert to B&W but can't go the other way!
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Andrew Rodney
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Chris Kern

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #7 on: November 23, 2017, 05:07:53 PM »

Scan at the highest optimal resolution if possible. Then you'll have all the data possible for all needs from that one scan.

A while back, I scanned a 7.5x10-inch print of my great-grandfather's home that was made in 1895.  The scan resolution was 1200 dpi. The original had been exposed to light over the intervening 100+ years, and was a bit faded.  I suspect that cost me some detail in the shadows, but the sharpness amazed me.  A 19x26-inch enlargement that I made looks fine at any reasonable viewing distance—and remarkably good even using the classic photographer's test for acuity: i.e., at the end of my nose.

saiguy

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #8 on: November 23, 2017, 06:17:19 PM »

Chris Kern,  That's a beautiful photo scan, nice house too.

Mark Segal in his SF8 book talks about the 2 different approaches, max scanner res., and right sizing. I have been using right size which for me from 35mm slides is an out put for 5x7 inch print at 300 ppi. This is for a general purpose archive. If a large print is needed I would just rescan.

Digitaldog, Scanning B&W in RGB allows access to more PS tools. It's particularly useful if there are photo restoration issues. If I print I use the Advanced B&W mode and do not convert.

Maybe the 600 ppi is a pre press norm. Seems to have no support here.

Thanks for all replies,

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digitaldog

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #9 on: November 23, 2017, 06:28:17 PM »

Digitaldog, Scanning B&W in RGB allows access to more PS tools.
Kind of doubt that if the original itself is in B&W, otherwise I agree. Scan color IF you wish to convert to B&W or better, have both options. Kind of like scanning big; you don't need to rescan (assuming the scanner is of sufficient quality for your needs) plus you have no guarantee that in the future, that film or print will be around or in the same condition as the first time you scanned it. So my stance, as someone who's reviewed, sold, used and provided scans in a 'service bureau' (last century) is scan once, highest resolution and be done with it.
600PPI, 300PPI, folks all over the net believe there's some standard value to always use; not so. Like the old urban legend all displays are 72PPI (nope) or that all scans for all prints should be 300PPI (or the printer produces or must have 300DPI), nope. 
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Andrew Rodney
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TonyW

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #10 on: November 23, 2017, 06:48:45 PM »

If you can guarantee that you will always have access to the print to rescan then fine scan at the lowest resolution you need at the time.  However if you scan at optimal resolution (you will need to find this for your scanner) then you will have the best data to work with regardless of final output size and will not need to find the original - storage is pretty cheap these days and if it is worth preserving then...

I mentioned scanning for restoration of less than pristine prints and if you do this type of work do not underestimate the value of scanning at higher sampling rates e.g. 1200.  Doing so may assist with bringing detail in even the damaged areas to aid in the restoration process.

Finally as a digital rule of thumb if you require to end up with ‘X’ amount of data it is not a bad idea to start out with 2x ‘X’ to give some headroom to what happens in post prior to final output size
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saiguy

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #11 on: November 23, 2017, 06:57:27 PM »

Digitaldog, Katrin Eismann says to scan B&W in color mode and gives ample reasons why in her Photoshop Restoration & Retouching book.

I am starting a project to scan nearly 9000 Kodachrome 35mm slides. Maybe a dozen or 2 will later get rescanned. Won't know of such selects till the project is done and can be viewed. All are from 1977 to 2004 and shot in India. Of course all of these are color. My friend does have many historic B&W that will be scanned later.

That's why I plan to use a 5x7 general use size. I can get good letter size prints from them on my 3880 printer. Comparing a native 5x7 print to a letter size of the same file. my eyes can't see degradation.
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digitaldog

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #12 on: November 23, 2017, 07:00:09 PM »

Digitaldog, Katrin Eismann says to scan B&W in color mode and gives ample reasons why in her Photoshop Restoration & Retouching book.
I've know her for decades and respect her enormously. I don't see the point. But then, if the original is B&W, depending on the scanning software, it is possible that the results setting it to grayscale could be suboptimal; the scanner IS scanning in color; alway! What it does with that trilinear color data to get grayscale can differ. But scanning a color image; you've got a lot of color data for the conversion so I'd never scan in anything but color IF I wanted B&W.
« Last Edit: December 19, 2017, 10:36:07 AM by digitaldog »
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Andrew Rodney
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saiguy

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #13 on: November 23, 2017, 07:16:51 PM »

TonyW,  When I get to my friends B&W I will be using settings similar to your suggestions. There may be only 100 of them and would require what you are saying.

Can you comment on my general purpose size for the 9k slides. They will use them to put together presentations, LR Collections, maybe publish to SmugMug. They might get a photo printer for letter size max prints.

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CeeVee

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #14 on: November 23, 2017, 08:29:54 PM »

I have been asked to provide scans from B&W originals in RGB. I concluded (after requesting clarification) that the rationale was simply that the end user simply didn't want to bother with anything else.

Sent from my Pixel XL using Tapatalk

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Chris Kern

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #15 on: November 23, 2017, 10:11:47 PM »

nice house too.

The photograph probably was made just a couple of years after the house was built.  The backstory is here.  Some time after I wrote that essay in 2009, my sister located the original print while we were closing up my parents' home after my father's death.  And shortly after that, a distant cousin sent me a newspaper clipping that confirmed the photo was made in 1895; it also authoritatively identified the individuals in the tableau—almost all of them relatives of mine, although I previously had never heard most of the names.

TonyW

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #16 on: November 24, 2017, 05:35:27 AM »

TonyW,  When I get to my friends B&W I will be using settings similar to your suggestions. There may be only 100 of them and would require what you are saying.

Can you comment on my general purpose size for the 9k slides. They will use them to put together presentations, LR Collections, maybe publish to SmugMug. They might get a photo printer for letter size max prints.
9k slides is quite a job and the requirements for storage quite high.  Other than printing image size requirement probably quite modest and you may want to be selective in how you scan bearing in mind purpose - only a decision that you can make.

FWIW just a few thoughts:

I would be looking at getting the optimum data from the image and using a Nikon scanner that get close to their claimed 4000 spi I would be tempted to go for max.  But that may not necessarily be the best for your project?

My assumptions
Your print requirements max. Letter size 8.5" x 11" @ 300 PPI = 2,550 x 3,300 = 8.4 MP

35mm film = 36 x 24 mm = 1.42" x 0.94"

1. Scan for the maximum size you are going to print (in this case assuming print ppi required 300) so in the case of letter size (8.5"x11") you are going to need a scan comprising of 2550 x 3300 pixels. The pixel image size being 8.42 megapixels
Or
2.  Scan at your scanners maximum optical resolution (believed to be 4000 spi for Nikon film scanner) which will create 3780 x 5669 pixels.  The pixel image size being approx 21.43 megapixels approx 2.5x the size of the lesser scan.  If you print Letter size from this you will be sending 515 ppi to the printer (close to the highest Canon printers require of 600 ppi).  Will it make a difference?  You may want to experiment and find out for your particular images

Which will be better for purpose depends on what remedial work you need to undertake and if the original contains the detail to make scanning at a higher (optimum) resolution worthwhile. 

If you need to keep file size down and you are going to require remedial work on the image then IMO it may be worth while to scan at the optimal resolution, work on the image then resample to finished size and discard the larger working file
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kers

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #17 on: November 24, 2017, 07:50:16 AM »

... a distant cousin sent me a newspaper clipping that confirmed the photo was made in 1895 ...

a beautiful slice of time !
One of the main attractions of photographs..
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Pieter Kers
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saiguy

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #18 on: November 24, 2017, 08:47:31 AM »

TonyW,

The Essay is great. Anyone scanning old photos should read it.

In Mark Segal's SF8 book he examines the Right Size & Max Size debate. Using an old 35mm Kodachrome slide BTW. I'll quote him, hoping that is OK to do;  "My conclusion, based on this test and other work, is that for most intents these aren’t choices over which to lose much sleep".

The only remedial work expected is to address any cleanup that SF8 tools and Neat Image don't handle sufficiently.

Will go with your advise and use an out put size for letter. That will be 7.5x11 inch I believe. If they get a printer, likely will be a Canon, so will use 300 ppi. File size will be about 60 MB.

thank you again
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Mark D Segal

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Re: Scan B&W photos/negs at 600 ppi. Is this best practice.
« Reply #19 on: November 24, 2017, 09:56:22 AM »

Digitaldog, Katrin Eismann says to scan B&W in color mode and gives ample reasons why in her Photoshop Restoration & Retouching book.

I am starting a project to scan nearly 9000 Kodachrome 35mm slides. Maybe a dozen or 2 will later get rescanned. Won't know of such selects till the project is done and can be viewed. All are from 1977 to 2004 and shot in India. Of course all of these are color. My friend does have many historic B&W that will be scanned later.

That's why I plan to use a 5x7 general use size. I can get good letter size prints from them on my 3880 printer. Comparing a native 5x7 print to a letter size of the same file. my eyes can't see degradation.

I think it may time to do a review of fundamentals here.

Let's start with the "optical resolution of the scanner" - the maximum the hardware can resolve without resampling the data. We throw this expression around, but it doesn't necessarily mean what the scanner specs say it is. For example, you can buy a scanner that rates itself at 6000 PPI (or DPI, same thing in this context) but when you test it with a resolution target you find that the EFFECTIVE maximum resolution may top-out at 3000 (page 125 of my SilverFast book provides some sobering information on several scanners in this regard). The scanner manufacturer isn't necessarily lying - what they call 6000 may well describe how the sensor is designed, but other factors such as lens quality, the lighting system, the flatness of field, and others can impact the EFFECTIVE outcome of scanning. Those factors will not vary as a function of the resolution you select. So if the scanner can't really deliver any more than say an EFFECTIVE 3000, it's pointless packing more unusable information into the file.

Now let's look at the "storage is cheap" argument. While that may be true, it's useful to consider how much storage you'll need as a function of file size. Firstly, you'll want to back-up the files you create. So right there, double the storage you start with. Then there is processing. If you are processing them "non-destructively" in Lightroom, metadata adds very little to file size, but if you are doing so in Photoshop, layers easily double the file size, if not much more, and assuming you wish to preserve those layers (the "non-destructive" aspect) you can at least double the file size again, along with its associated back-up. So what may start life as a 60MB storage requirement, for example, can easily end-up as at least a 240MB storage requirement by the time you finish - i.e. 4x what you started with. Cheap X 4 may no longer be so cheap. Add to this the consideration that larger files can take longer to retrieve, edit and save than smaller files and you end-up perhaps consuming more time than necessary for your purposes.

9000 slides is a lot of scanning - a daunting exercise in fact. So let's look at this with a bit of arithmetic. I'm assuming these are 24 * 36mm slides, so the maximum dimension is 1.5 inches (and I'm assuming no cropping here - cropping changes the calculations). The maximum print size you EVER IN THIS LIFETIME intend to make is letter size, with say a one inch border on each side, so the maximum dimension of the photo itself is 9 inches. You want to print it in a Canon printer at a "native" resolution of the Canon driver of 300 PPI. So you need 9 x 300 pixels, or 2700 total output pixels on the maximum dimension. To pack 2700 output pixels into a 1.5 inch input, you'll need 2700/1.5 = 1800 input PPI setting for the scan resolution. Or seen in a perhaps more intuitive obverse manner, if you scan that 1.5 inches at 1800 pixels per inch, you obtain 1.5 x 1800 = 2700 total pixels, which when divided by your 9 inch output (the print) gives you the 300 PPI the printer driver likes.

Now let's see what file size that creates using the formula explained on page 124 of my book (which delivers the same results that scanner software such as SilverFast reports for the same settings): the result is 27.8 MB, assuming 16 bit depth for the scanning, and a 6*9 inch photo (say on an 8.5 x 11 inch sheet, but only the photo dimensions count). Now let's say for some reason or other you decide you want to provide for an 11 * 14 inch print (or given a 1 inch border, 9 * 12 inch printed photo on an 11* 14 sheet) even though you may never ever in your lifetime make one. Applying the same formula with all the same inputs except for the change in photo dimensions, you'll have a file size of 55.6 MB - double what you need. And, by the way, you'll need 3600 output pixels on the maximum photo dimension to achieve this result, which means you need to scan at 2400 input PPI instead of the 1800 needed for the 6*9 inch photo, so scanning will take longer.

Now that we have all that straightened away, let's look at the size of this job - as I mentioned above, daunting. You would want to automate as much as possible. For this I would recommend that you look carefully at SilverFast's batch scanning capabilities.

You will want to get the scans in reasonably good shape at the scan stage to minimize time spent in post-scan editing. How much editing to do at the scan versus the post-scan stage is a mixture of technical reality, taste and judgment, all explained in my book - too much of a long story to put in a forum post, but if I had to put the most basic advice into a nutshell for you, whatever balance you wish to strike about what edits to do where, at the least, make sure when you scan you are sending to file an image that is relatively open (no excessive contrast) without blocked-up highlights and shadows, i.e. minimizing highlight and shadow clipping, and make sure your scanner is properly colour-managed (decent profiles etc.). Once the image file is created and you need to do any further editing and printing, I would recommend using Lightroom. The edits are all meta-data, non-destructive, preserved for future editing, and the workflow from editing to printing within that one application is seamless. Lightroom also has very good tools for sharpening and noise control, which work well with moderate film grain as well.

On the colour versus B&W scanning, I think we are all agreed that if you are scanning colour originals, scan them in colour mode and if you wish to convert them to B&W, do that afterward. Lightroom is great for this. This allows you to conserve the maximum amount of control possible over the eventual tonality of the B&W renditions.
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Mark D Segal (formerly MarkDS)
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