Luminous Landscape Forum

Raw & Post Processing, Printing => Digital Image Processing => Topic started by: PSA DC-9-30 on April 25, 2013, 08:35:51 pm

Title: Upres and then downsample vs. printing at low ppi?
Post by: PSA DC-9-30 on April 25, 2013, 08:35:51 pm
Well, I tried printing a ~ 3600 x 2700 px file at approx 21.5" x 14.25". I upres-ed the file to exactly twice the linear dimension (e.g. 7200 px wide), then cropped to 21.5 x 14.25 at 300 ppi, followed by sharpening, etc. The result was disappointing, and did not have the detail and sharpness I want.

Plan B is to print at 18 x 11.5 to go in an 18 x 24" mat. I am going to print the original file without upsampling (will be about 200ppi, which is low!) as well as the upsampled file cropped to this dimension (at 300 ppi) to compare them.

If given a choice between printing at 200 ppi vs. upres-ing and downsampling to the desired dimensions at 300 ppi, which would you go for? (This is for a friend who has her heart set on a large print of this particular photo).

I am also curious to know your sharpening workflow with upres-ing. I do capture sharpening in LR4 and then additional (output) sharpening in PS using Smart Sharpen, or progressive sharpening...

Is there any utility to sharpening before upres-ing?

Any ideas are appreciated.
Kevin
Title: Re: Upres and then downsample vs. printing at low ppi?
Post by: PeterAit on April 25, 2013, 10:02:46 pm
I think that up-sampling by a factor of 2 is asking too much. There's only so much the upsampling algorithms can do in terms of inventing details. I suggest not obsessing about the resolution as long as it is 180 ppi or more, the printer driver will, in my experience, do what is needed.
Title: Re: Upres and then downsample vs. printing at low ppi?
Post by: bill t. on April 25, 2013, 10:03:49 pm
Download the trial version of Resize 7.5.  The user interface is kinda goofy and stutters a lot, but the results are good.

Just under the navigator image, click on "100" to get a 100% view.

Choose Image Type : General Purpose

Set the Resolution to 300 for Canon, or 360 for Epson

Select your desired inch dimensions, or some percentage.  200% works especially well.

If your bare input image needs sharpening, you are generally best off clicking the Sharpening switch On, selecting Unsharp Mask, then choosing Radius : 1 or 2, and Amount : about 80.  If you wish to sharpen later, PS Smart Sharpen is your best pick, but I think I get better results with Resize's built in Unsharp Mask when applied during resizing.  BTW InFocus does not play well with Resize'd images.

I used to meticulously upsize 2x, Smart Sharpen, then print.  Resize 7.5 and PhotoZoom5 are better, by a lot.

FWIW, if your original is kinda grungy, Alien Skin Blowup 3 may be worth a try.  It produces the cleanest looking edges, with some distortion of fine shapes.  But Resize 7.5 and PhotoZoom5 both produce at least good and sometimes amazing results with clean originals.  The difference shows up more in prints than on the screen.  But to be complete, you need to be going at least 150% and more like 200% for any of those resize programs to make sense over PS's Bicubic Smooth resize followed by Smart Sharpen.

Edit: and the DC9 was the best damn passenger plane that ever was.  Sitting in the first half the plane, it was like flying in a glider.
Title: Re: Upres and then downsample vs. printing at low ppi?
Post by: jrsforums on April 25, 2013, 11:05:29 pm
PSA...

You say you are using Lightroom.  After sharpening and other adjustments, including clarity, how does your image look on the screen? Does it need creative sharpening or is it pretty much the way you want it?  BTW...while PS is best for more than 'capture' sharpening, LR can do selective sharpening and blurring pretty well.

When you get it the way you want it, try printing in LR.  THe print sharpening is based on the old Photokit sharpening that many used in PS.  Based on the size you are printing to and the PPI, it will apply a proper amount of sharpening....you can adjust the amount from normal, up or down.

BTW, as "Bill T." said, it is important that you set the PPI to what the printer expects 300/600 for Canon, 360/720 for Epson.  The print driver interpolation is poor at best and will not give you the best results.

If you are not comfortable or experienced with a familiar workflow in PS, LR can often give you extremely good results that only an expert could exceed.

Personally, I use Qimage, which I feel is a bit better than LR in interpolation and sharpening, but, while inexpensive and easy to use, is another piece of software you would need to learn.
Title: Re: Upres and then downsample vs. printing at low ppi?
Post by: Schewe on April 26, 2013, 12:16:40 am
Any ideas are appreciated.

Have a read of this: The Art Of The Up-Res (http://www.digitalphotopro.com/technique/software-technique/the-art-of-the-up-res.html) and then read this: The Right Resolution (http://www.digitalphotopro.com/technique/workflow/the-right-resolution.html) and then get back you us about what the image source is and what printer/paper you are using. And no, you want to output sharpen AFTER the upsampling.
Title: Re: Upres and then downsample vs. printing at low ppi?
Post by: Bart_van_der_Wolf on April 26, 2013, 05:20:19 am
Well, I tried printing a ~ 3600 x 2700 px file at approx 21.5" x 14.25". I upres-ed the file to exactly twice the linear dimension (e.g. 7200 px wide), then cropped to 21.5 x 14.25 at 300 ppi, followed by sharpening, etc. The result was disappointing, and did not have the detail and sharpness I want.

Hi Kevin,

3600 pixels at 21.5 inch output, equals 167 PPI. That will not look very sharp at close viewing distance, but there is something that can be done to improve the situation, although it also depends a bit on the specific image content. Up-sampling by itself will not give you much, although it does allow to get closer to the native printer resolution. That will allow to use a better upsampling algorithm than the printer driver will use, AND you can apply output sharpening at that native printer resolution.

You can also use a dedicated up-sampling program like Benvista's Photozoom Pro. That will actually add resolution to edge detail, as outlined in this thread (http://www.luminous-landscape.com/forum/index.php?topic=62609.msg505337#msg505337).

Quote
Plan B is to print at 18 x 11.5 to go in an 18 x 24" mat. I am going to print the original file without upsampling (will be about 200ppi, which is low!) as well as the upsampled file cropped to this dimension (at 300 ppi) to compare them.

The issue with sending 200PPI to the printer is that the printer driver will still do an up-sampling, behind your back, to the native printer resolution, and doesn't allow to do additional output sharpening at that stage. What that native printer resolution is, depends on the printer brand, and print driver settings. It's usually 300/600PPI for e.g. Canon and HP printers, and 360/720PPI for Epson printers. The printer driver's resampling algorithm delivers relatively low quality, so you're usually much better off doing it yourself.

Quote
If given a choice between printing at 200 ppi vs. upres-ing and downsampling to the desired dimensions at 300 ppi, which would you go for? (This is for a friend who has her heart set on a large print of this particular photo).

Definitely go for 300PPI if that's the printer driver requirement, but you can  get better quality by using something like Photozoom at 600PPI (if that is the native printer resolution).

Quote
I am also curious to know your sharpening workflow with upres-ing. I do capture sharpening in LR4 and then additional (output) sharpening in PS using Smart Sharpen, or progressive sharpening...

Assuming you do a proper Capture sharpening, that's okay. It should only compensate for lens and sensor+demosaicing blur, nothing else. When you exaggerate things here, it will create artifacts that will only become bigger and more noticeable on enlarged output.

Quote
Is there any utility to sharpening before upres-ing?

Be very careful here. You are best off leaving it to proper Capture sharpening, and some Creative 'sharpening' (more of a spatial frequency based local contrast enhancement) at the pre-enlargement stage. LR doesn't offer as much choice for postprocessing your output file as e.g. Photoshop or other photo-editors.

Topaz Labs does offer some possibilities to use their filters outside of Photoshop, and use adjustment layers for increased control, via their photoFXlab utility. They also offer some plugins to increase and/or manipulate resolution (called Infocus) and detail (called Detail, which also offers basic deconvolution sharpening).

Make sure to check out PhotoZoom Pro, because I estimate it will give you the most benefits for the particular print scenario that you outlined.

Another application that should not go unmentioned, is Qimage Ultimate. It's a Windows application for generating very good quality output, because it automatically does the upsampling for you with superior algorithms, and uses an adjustable automatic output sharpening algorithm (called DFS, or Deep Focus Sharpening) that does not create halos. Qimage does have a bit of a learning curve if you really want to benefit from its many capabilities.

Cheers,
Bart
Title: Re: Upres and then downsample vs. printing at low ppi?
Post by: PSA DC-9-30 on April 30, 2013, 08:01:15 pm
Have a read of this: The Art Of The Up-Res (http://www.digitalphotopro.com/technique/software-technique/the-art-of-the-up-res.html) and then read this: The Right Resolution (http://www.digitalphotopro.com/technique/workflow/the-right-resolution.html) and then get back you us about what the image source is and what printer/paper you are using. And no, you want to output sharpen AFTER the upsampling.

Thanks to everyone for the ideas. The two links above were helpful also. Anyway, in case anyone is interested, and to answer a few questions...

I decided to up-res to 200% in CS2 using bicubic smoother, with only minimal capture sharpening in LR4 (as before). (I export from LR4 as 16bits/channel) But this time I downsampled to 18 x 11.5" at 300ppi (for Canon). I sharpened rather agressively with Smart Sharpen, but was happy with the result.  I cannot print from LR yet--I work with a good local printer/framer who has a fairly new Canon large format printer (i'm pretty sure it's an ipf9400). He does not have LR yet. (I advised him to get it!). The paper I used is Hahnemuhle photo satin for Canon. 

The camera I used in 2008 for this shot was an Oly E-510. I am well aware of the limitations of this camera/sensor, but I believe that even a mediocre 10MP sensor at low ISO should be able to print at this size. The onus was on me to produce a good result.

Anyway, the results were much better than previous larger (21.5 x 14.25") version. We were both quite happy with the improved sharpness and detail. I soft proof these on my monitor at home and then on my printer's monitor for a final check. I forgot to notice what rendering intent we used, but the print looked nearly identical to the on-screen version.

I am still fairly new to printing and am looking forward to Jeff's next book and trying out some of the other programs suggested here. 

Here is a much smaller jpg-ized version of the final product.

Any more comments/suggestions are welcome.