Colors off when file is re-scaled

[John Towler]

I've got a strange problem. When I print a test image at half size (5.5 in x 8 in. sheet) the color is fine. When I print the image full size (11 in. x 8 in. sheet) the colors are way off: blues, cyans and greens are over-saturated, while reds and magentas are under-saturated. The half-size image was scaled down in Photoshop, and both prints where printed with the same profile.

The same thing is happening in Lightroom. In Lightroom, if I print using Canon Print Studio Pro, both prints are fine (Print Studio Pro is quitting on me in Photoshop; I'm asking for help with Canon on that.) The full size print is also fine when printed with other image apps.

It was suggested I reset Photoshop and Lightroom preferences back to defaults, but that hasn't solved the problem.

iMac 21 in, Mac OS 10.14.5, Photoshop CC 2019 (latest version)

[Kevin Stohlmeyer]

What color mode is your file using? What are you color management settings?

When you look at your print options - do you let Photoshop decide color or printer?

[John Towler]

The color mode is RGB, and Photoshop is managing color. I'm careful to ensure the same paper profile is used in both cases.

[Kevin Stohlmeyer]

Here's a document that may help explain:

Print with color management in Photoshop

[John Towler]

Thanks for the link. I looked at it, and can't see any obvious errors I've been making.

There are two things I should point out. First, I was previously making prints in Photoshop and Lightroom at the problematic size with no color shifts. One day, a print was markedly off, and a test file with color bars, patches, and gray scales, was also printing differently at the two sizes in both apps.

The other thing, which I forgot to mention, was that I tried printing from Photoshop at 8.5 x 11 with the printer managing color, and the output was acceptable, if not outstanding. But a print at that size with Photoshop managing color was way off, although the smaller test print was fine; the only change being that the smaller one had been scaled down in Photoshop.

Still perplexed.

[Kevin Stohlmeyer]

When you say you are printing at different sizes, are you scaling in the print window or changing the pixel dimensions of the file?

Either one can affect color.

[John Towler]

I re-scaled using the Image Size function in Photoshop. Interestingly, the smaller, scaled version prints fine, while the original, unscaled file is the one printing with wonky colors.

[Kevin Stohlmeyer]

what are your full dimensions including PPI?

[John Towler]

The original file is 1600 x 2000, printed at 200 PPI; the scaled file is 800 x 1000, also printed at 200 PPI.