Background color shift even if set to constant swatch?

[_FT_]

I take pictures for a client who has a shoes brand. All the shoes have a constant colored background, which was picked before the beginning of the project, and all shoes get cut out and placed on a color applied by an action which has been unedited in 3 years.

They noticed there is a slight shift in color from time to time, portrayed in the screenshot (screenshots have a contrast layer on top to exacerbate the issue). What could cause the issue?

All pics are edited in SRGB 8bit to avoid issues, and the photoshop Color Settings have been set to North america General purpose 2 - preserve profiles for years. Can anyone help? thanks!

[D Fosse]

Numbers are color space specific. As long as you make sure the sRGB profile is embedded in every file, the color is unambiguously defined and invariable. The working space or general color settings are not important, that's just defaults. The embedded profile will always override that.

The wild card here is jpeg compression. That can easily shift a color channel a value or two, enough so that you can see it if you put them side by side. I'm guessing that's the case here. The only way to avoid that is to avoid jpeg, which is by nature unpredictable and inconsistent. PNG is better. It also uses compression, but a non-destructive type that doesn't change any values.

[_FT_]

I agree with you, however client requested jpgs for the website, otherwise wordpress or whatever platform would handle the conversion itself, so I did my best to preserve the output.

here is what I did: i opened two pictures from two shoots in psd, freshly exported jpgs and old exported jpgs. (there is a contrast mask). all pics are in srgb.

newly exported files show the same divergence toward red, while the old exports go towards yellow and red respectively. 

this is unfortunate, I'm looking unprofessional towards the client while it's not my fault directly...

[D Fosse]

These fall into two distinct groups. One has variances of one or two values per channel, and that's typical of different jpeg compression algorithms. This is inevitable with jpeg.

The other group is much more different, up to five values per channel. That is clearly visible, and cannot be explained by jpeg compression. This has to be that the sRGB profile has not been correctly handled - not embedded, not converted correctly. I have never seen this happen and I cannot think of any way that could happen.

All I can say now is revisit your procedures and make absolutely sure the sRGB profile is embedded when you export.

[_FT_]

i think this is just one value in each direction — there is a strong curve applied on the final comparison to show there IS a difference so the values are pushed further. the srgb profile is embedded in the starting and ending image!

[D Fosse]

@_FT_ 

These are the values from your untagged screenshot (converted to sRGB):

[Earth Oliver]

"while it's not my fault directly..."

No, it's definitely your fault. Somewhere within your workflow, you're not color-managing properly. That's it. This isn't a Ps error, it's a user error. More than likely, it has something to do with the settings in the Bridge export. Or it could be several other things, but without seeing all the files and a video of your exact workflow, troubleshooting is nearly impossible. 

[_FT_]

@D Fosse i'm sorry the screenshot is untagged. yes the values diverge a lot but that's because i opened the exported files in PS along with the psd and put a strong curve to exacerbate the divergence. thank you for pointing out values but I don't understand what you mean with your last reply 🙂

I attached an image of the issue on original colors. as you can see it's very slight, but noticeable on confining images on the website.

@Earth Oliver starting psd files are in srgb IEC61etc, final jpg files all report "srgb IEC61etc" in color profile, i don't know what else I can do or check...

[c.pfaffenbichler]

Please set the Status Bar to »Document Profile« and post screenshots with the pertinent Panels (Toolbar, Layers, Options Bar, …) visible of two images that do not match.

[_FT_]

so here it is, and here is what I did: i opened two pictures from two shoots in psd, freshly exported jpgs and old exported jpgs. (there is a contrast mask). all pics are in srgb.

newly exported files show the same divergence toward red, while the old exports go towards yellow and red respectively. 

[c.pfaffenbichler]

so here it is, and here is what I did: i opened two pictures from two shoots in psd, freshly exported jpgs and old exported jpgs. (there is a contrast mask). all pics are in srgb.

newly exported files show the same divergence toward red, while the old exports go towards yellow and red respectively. 

By @_FT_

What were the exact export settings? 

[_FT_]

i either export batches with Image Processor tool, or from Bridge with the Export panel. here are the settings:

[c.pfaffenbichler]

I cannot reproduce the issue with Image Processor. 

Can you reproduce the issue reliably or does it appear randomly? 

[_FT_]

I have done further exports with image processor and the pictures keep having very very slight differences. I guess it's the compression.

is there any chance the monitor could be the issue? i work from a macbook pro but i have one external monitor at home and a different one in the studio.

[c.pfaffenbichler]

Does exporting to a file format that does not employ lossy compression result in the expected results? 

[_FT_]

...I feel like an idiot since I have checked all settings but never tried this.

I stacked an old psd, a recent psd, a freshly exported bridge png, and a freshly exported tiff from image processor. I don't have old lossless exports but besides that, all these files perfectly identical even with the strongest contrast curve.

I guess we have a final answer: compression is the sole issue, and it probably pushed the original colour in opposite directions enough that difference is noticeable to the naked eye in adjacent images. Do you agree with me?

Can't believe I haven't done this before. thank you @c.pfaffenbichler.

(paging @Earth Oliver @D Fosse who are helping on another post)

[shaquon_knauls]

Its light


Shaquon Knauls

[c.pfaffenbichler]

Please elaborate.