Resizing/resampling for printing?

Veritable said:

Is it recommended to resample (change the resolution) of images for printing to match the printer's native resolution and print size?

I'd like to get some of my photos printed on luster (semi-gloss) paper at a local professional photo print shop. They have Canon Pro 1000, which prints natively at 300dpi (I believe). They told me they take JPGs and TIFFs, and that I don't need to resize/resample (change the resolution) of my images for printing.

My cameras produce images 4000x6000 pixels. If I want to achieve the best possible output on 8x10" or 11x14" paper, should I resample/downsample them and perhaps apply sharpening as a final step, before printing? Similarly, for lower-res images, upsample them before printing?

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Mostly, I suggest that you not resize / resample a file you're sending to a service to have printed.

* The odds that you and your software will do a substantially better job than a professional service and its software are low. The odds that you and your software will do a substantially worse job than a professional service and its software are not low.

* Typically you don't know precisely how many pixels are needed, and if you don't get it exactly correct, then the service would have to perform a second resize / resample and probably related sharpening. Every resize / resample at a minimum presents an opportunity for some quality loss.

However, do crop it to the proportions of the print, e.g., if you want an 8x10" print from from 4000x6000 pixels, then crop to 4000x5000, etc.

Whether / how you should sharpen versus expect them to sharpen is something you might ask them.

Veritable said:

A related question: I use sRGB profile in my camera & post-processing (LR & C1). Do I need to worry about the printer & paper color profile for printing, and apply them while preparing for print? I do color calibration of my computer monitor.

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That is really a function of what sorts of files this professional service accepts. Ideally you'd use ProPhoto RGB (or LR's counterpart, Melissa RGB, which has the same primaries but is linear / gamma = 1.0), and they'd provide you with the ICC printing profile for their printer with the paper on which they'll print, and you can use that to soft-proof, final-edit, and ultimately perform a 'convert to profile' and save and submit that file. But only a small fraction of printing services support that. Many of them require you submit your files in sRGB.

OTOH, depending on the gamut of your source image, sRGB can be marginal for high-quality printing. Even some fairly modest printers can print some colors outside of sRGB. Here's a gamut plot made at ICC View of my modest little Epson R280 printing on Red River Palo Duro Baryta paper (solid) versus sRGB (wireframe):



As you can see, there are large areas of yellow and orange, and modest areas of green, that I can print, but sRGB cannot describe. Adobe RGB is better but ProPhoto RGB is even better.

Agree. We tell all of our clients not to resize anything as that is taken care of here.

I would always have your camera set to RGB especially when printing. A 20mp sensor 4000x6000 divided by 300 will give you a 13.3x20" image with no uprezzing at the native resolution. All of our uprezzing software does a fantastic job to 200% or higher.

Thank you both for replies and detail explanation, very helpful.

I gather that a professional print shop will/may do additional post-processing to prepare my images for print, and therefore I should not attempt to do it myself.

What about print shops that merely print (on a good printer), but don't edit the images? Or if I were to print at home? Can I potentially improve the result by resampling and sharpening? I found several videos that suggest it, e.g.:

I should be able to tell the shop not to resize the image at all, right? I.e., print at 100%.

Dan Berg said:

I would always have your camera set to RGB especially when printing.

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Do you mean Adobe RGB or sRGB?

Better advice might be to shoot in raw.

Veritable said:

Thank you both for replies and detail explanation, very helpful.

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You're welcome, and glad you think so.

Veritable said:

I gather that a professional print shop will/may do additional post-processing to prepare my images for print, and therefore I should not attempt to do it myself.

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That's not correct. You should edit to your taste: white balance, lightness, contrast, cropping, etc. You probably should also do at least some sharpening.

But you should not do, and any printing service may do, resizing / resampling. Also, typically there will be some final sharpening that accompanies / follows any final resizing.

Veritable said:

What about print shops that merely print (on a good printer), but don't edit the images?

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Any decent printing service should offer, and the better ones may even default to, 'no corrections' prints, which should mean the service does nothing other than resize / resample as needed. However, most printing services also offer, and the more consumer-oriented ones usually default to, some automatic corrections. For example, if the service's software thinks your image is too dark, then the software may lighten the image.

Veritable said:

Or if I were to print at home? Can I potentially improve the result by resampling and sharpening? I found several videos that suggest it, e.g.:

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IMO for home printing, in most cases it is hard to beat Qimage Ultimate (for Windows) or the related product Qimage One (for Mac OS). Qimage will automatically resize / resample to precisely what your printer needs, and typically do a very good job of that. It also offers user-adjustable print sharpening, and again, typically do a very good job of that.

Adobe Lightroom's Print module is also fine for most home printing. Epson Print Layout is also fine for most home printing, is free, and (as far as I can determine) works with any Epson inkjet printer. Canon has two different photo printing software options, each of which works with some but not all Canon inkjet printers.

Veritable said:

I should be able to tell the shop not to resize the image at all, right? I.e., print at 100%.

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Nope. You send them whatever file and, unless you just happen to send them precisely the right number of pixels (unlikely), they will resize it to whatever their printer needs to print the size you ordered. Also, given that almost all of them print borderless, you cannot precisely control (except maybe with some trial and error) the size.

But I would not worry about that. Typically it's fine. Unless you send them far fewer pixels than the given print size calls for, the quality should not be a problem.

Certainly agree about RAW.

Adobe RGB is the largest color space and in my opinion should always be set in camera.

Also any time you see RGB without the s it is RGB,

Dan Berg said:

Certainly agree about RAW.

Adobe RGB is the largest color space and in my opinion should always be set in camera.

Also any time you see RGB without the s it is RGB,

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The camera's color space has no effect on RAW files, only in-camera JPEGs.

The question in my mind would be whether the service uses specialist software to resize or just relies on their printer driver to do the interpolation. Either may be OK, but if the service relies on the printer driver, the interpolation may not be superior to what can be done to the file prior to submission for printing.

Sharpening is another issue. Conventional wisdom is that sharpening should only be done to the final file size. If the printing service determines the file resolution for print, then presumably it would be applying sharpening. While this may not in most cases be a major issue, the amount of sharpening is discretionary and should be controlled by the photographer, as it will affect the appearance of the image. Applying sharpening before submitting an image that is subsequently resized by the printing service with perhaps added sharpening for printing is less than ideal.

Dan Berg said:

Certainly agree about RAW.

Adobe RGB is the largest color space and in my opinion should always be set in camera.

Also any time you see RGB without the s it is RGB,

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I have no idea what the last bit means.

But thanks for reminding me. I'd never noticed that my Canon R5 offers sRGB and Adobe RGB color spaces.

But I usually shoot RAW, so it mostly is unused by me.

Dan Berg said:

Also any time you see RGB without the s it is RGB,

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That is a rule I have never heard of and does not seem to be a common usage.

Yes I know that. As the owner of a print studio about 75% of consumer printers are still sending JPEG's as they do not shoot in RAW.

I was only responding to a poster above that questioned if I meant RGB or sRGB?

I typed RGB which always means RGB. It takes an s at the end to mean sRGB.

Dan Berg said:

Yes I know that. As the owner of a print studio about 75% of consumer printers are still sending JPEG's as they do not shoot in RAW.

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As the owner of a print studio, what file formats do you accept? It is my understanding that many printing businesses will not accept (lossless) TIFF files. Of course, normally RAW development software will require a color space assignment to prevent color inaccuracy.

Dan Berg said:

I typed RGB which always means RGB. It takes an s at the end to mean sRGB.

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There are a bunch (maybe dozens) of different RGB color spaces. If you just say "RGB" it does not mean anything to me. I believe you meant "Adobe RGB". but I would not assume that. As you said about sRGB requiring an "s" in front of it, Adobe RGB requires an "Adobe" in front of it.

--
George
.
Feel free to retouch any photograph I post in these forums. It probably needs it.

In camera you only have two choices, Adobe RGB and sRGB and that is what I was referring to. Since there are not three choices we both are right to a degree with you being technically correct.

--
Dan Berg
http://bergsprintstudio.com/workshops/
Printmaking and Photo Mounting Workshops

I ALWAYS resize / resample to the final print size.

The decision has nothing to do with the technology involved. I work closely with a friend who runs a professional printing studio when I need prints bigger than the 17" width I can print myself. I know what printers he uses, what RIP software he uses, and I trust his expertise.

But he's not going to mess around with sharpening, and his RIP's interpolation algorithms don't know anything about the sharpening qualities I want.

I been printing for exhibitions for years, and between my experience and the studying I've done on visual perception, I have opinions about the type and degree of sharpening a print needs for different circumstances. This can only be done reliably when working on a file that's been resized for final print size. So this is how I do it.

Even if it means delivering a 6GB file over my FTP server.

To those who object that Photoshop won't do as good a job at interpolation as a dedicated RIP or the native print driver, please show us the evidence. I've never seen anything to suggest this.

Edit: Regarding color space, I edit in ProPhoto RGB at 16 bits (reduces any chance of clipping during editing) and leave it there. There is never a need to change the color space from your editing space if you're sending it to someone who used contemporary technology and who is using a properly color-managed workflow.

You should have a profile for the final output device and materials, but only for soft proofing. Do not convert to this color space! Or to any other. There's zero reason to.

paulraphael said:

To those who object that Photoshop won't do as good a job at interpolation as a dedicated RIP or the native print driver, please show us the evidence. I've never seen anything to suggest this.

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Here's a test posted in this forum of Qimage versus Lightroom's print module. IMO it shows a definite advantage for Qimage.

https://www.dpreview.com/forums/post/66782264

Obviously software evolves over time, but some software is better than other software and Photoshop is not the be-all and end-all for all purposes. Also, there's a large difference between what somebody who feels the need to come here and ask is likely to achieve, versus what an expert is likely to achieve. Obviously YMMV. That doesn't mean the general advice was wrong for the substantial majority of cases.

paulraphael said:

Edit: Regarding color space, I edit in ProPhoto RGB at 16 bits (reduces any chance of clipping during editing) and leave it there. There is never a need to change the color space from your editing space if you're sending it to someone who used contemporary technology and who is using a properly color-managed workflow.

You should have a profile for the final output device and materials, but only for soft proofing. Do not convert to this color space! Or to any other. There's zero reason to.

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I disagree on this last part. First, most consumer and even mid-level hobbyist printing services don't allow a fully color-managed workflow, or even accept files encoded in ProProto RGB. Some of them don't even accept or at least honor Adobe RGB files, and require sRGB. Also, most such services don't let you submit 16-bit files. And printing services that offer full color management tend to be substantially more expensive.

Second, even if you have the printing service's ICC profile to soft-proof and final-edit your image, and your image is encoded in ProPhoto RGB, if you send it to the service in ProPhoto RGB, you can't be certain whether they'll use relative colorimetric or perceptual rendering intent, and if relative colorimetric, whether they'll use black point compensation. If you 'convert to profile' yourself, then you bake in your preferences on those. Indeed, you can even use advanced techniques like having a perceptual-converted layer and a rel. col. layer, and use local masking to use different ones for different areas of the image.

Or to put it back to you differently, if the printing service is fully color-managed, why wouldn't you converter to its printing profile, using the conversion settings that seem best to you, and then embed that profile, retaining maximum control on your side?

NAwlins Contrarian said:

NAwlins Contrarian said:

To those who object that Photoshop won't do as good a job at interpolation as a dedicated RIP or the native print driver, please show us the evidence. I've never seen anything to suggest this.

Click to expand...

Here's a test posted in this forum of Qimage versus Lightroom's print module. IMO it shows a definite advantage for Qimage.

https://www.dpreview.com/forums/post/66782264

Click to expand...

I believe it is possible to match Qimage's printing with Photoshop, but it sure won't be easy. Sharpening and interpolation are quite complex to do right, and any minor change such as changing paper type, size, etc. that you make to the print requires doing both steps again. Experience helps, but setting the proper sharpening in particular always seems like guesswork because it doesn't look the same on screen as it does in the print. Most people don't even bother, so the prints suffer a little. Qimage handles all that behind the scenes.

--
George
.
Feel free to retouch any photograph I post in these forums. It probably needs it.

NAwlins Contrarian said:

NAwlins Contrarian said:

To those who object that Photoshop won't do as good a job at interpolation as a dedicated RIP or the native print driver, please show us the evidence. I've never seen anything to suggest this.

Click to expand...

Here's a test posted in this forum of Qimage versus Lightroom's print module. IMO it shows a definite advantage for Qimage.

https://www.dpreview.com/forums/post/66782264

Obviously software evolves over time, but some software is better than other software and Photoshop is not the be-all and end-all for all purposes. Also, there's a large difference between what somebody who feels the need to come here and ask is likely to achieve, versus what an expert is likely to achieve. Obviously YMMV. That doesn't mean the general advice was wrong for the substantial majority of cases.

Click to expand...

If I owned the large format printer and had the ability to control the Qimage settings and run tests, it's possible that I'd choose it over Photoshop. But since I have to do my testing and iterations on my own 17" printer, it's more important to me to be able to control the process.

The test results in that thread don't mean anything to me, because I don't know how the files were prepared. I use a sharpening workflow that allows me to get optimal results by treating each print size as a separate project. The only way for me to test this in a relevant way would be to prepare a file to the best of my ability in Photoshop, and compare that to an un-resized file sent to Qimage. No one else can do this test for me.

NAwlins Contrarian said:

NAwlins Contrarian said:

Edit: Regarding color space, I edit in ProPhoto RGB at 16 bits (reduces any chance of clipping during editing) and leave it there. There is never a need to change the color space from your editing space if you're sending it to someone who used contemporary technology and who is using a properly color-managed workflow.

You should have a profile for the final output device and materials, but only for soft proofing. Do not convert to this color space! Or to any other. There's zero reason to.

Click to expand...

I disagree on this last part. First, most consumer and even mid-level hobbyist printing services don't allow a fully color-managed workflow, or even accept files encoded in ProProto RGB. Some of them don't even accept or at least honor Adobe RGB files, and require sRGB. Also, most such services don't let you submit 16-bit files. And printing services that offer full color management tend to be substantially more expensive.

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Yes, for a consumer service (and for some backwards commercial services) you just have to follow their directions. I'm talking about making exhibition prints with a professional studio.

NAwlins Contrarian said:

Second, even if you have the printing service's ICC profile to soft-proof and final-edit your image, and your image is encoded in ProPhoto RGB, if you send it to the service in ProPhoto RGB, you can't be certain whether they'll use relative colorimetric or perceptual rendering intent, and if relative colorimetric, whether they'll use black point compensation. If you 'convert to profile' yourself, then you bake in your preferences on those. Indeed, you can even use advanced techniques like having a perceptual-converted layer and a rel. col. layer, and use local masking to use different ones for different areas of the image.

Or to put it back to you differently, if the printing service is fully color-managed, why wouldn't you converter to its printing profile, using the conversion settings that seem best to you, and then embed that profile, retaining maximum control on your side?

Click to expand...

These are fair points. I don't convert for a couple of reasons. I want to be open to the possibility of adjustments being made to the print file if there are any problems, and I'd rather do this before any profile conversion. Also, I want my printmaker to have flexibility with regard to what printer he uses. The paper choice is fixed, but for various reasons he may choose to use a different printer. In practice, with the kind of color gamut I work with, this has not led to any shifts that I find objectionable. If there are any concerns with rendering intent, we discuss them.

What's worked for me is to micromanage resizing and sharpening, but to leave profile conversion to the printer.