RGB colors constantly changing value

[sarahr20733269]

Hi everyone,

Let me first say I am not an expert in Photoshop, so forgive my ignorance.

I am working on files for digital fabric printing, which need to be in RGB for printing. I am saving them as a flattened .tiff as requested by the printer.

These files are manipulated photos, using filters etc, so they are simplified down to a few colors only.

Problem is, when I choose an RGB color from the picker, it looks fine. I save the file, come back to it later and the color value is different.

I am tearing my hair out to work out what is happening, and how to stop it.

I am working in the Adobe 1998 workspace and think maybe I should have left it in sRGB.

I noticed yesterday that the proof setup has Working CMYK ticked - would this be the reason?

If anyone can help I would be really appreciative.

Thanks in advance

Sarah

[Mylenium]

Yes, you need to read up on how color profiles and color management actually work. If your proof setup is set to CMYK, then inevitably you are not seeing the native RGB values, but rather the ones after the CMYK transform. The simple answer would be to simply forego all that CM stuff if you realyl only need to match specific numeric values and otehrwise assume a generic sRGB space.

Mylenium

[Test Screen Name]

Also, if you save as JPEG, then edit again, STOP DOING THAT. Every time you save as JPEG the colours are changed and the quality damaged.

[D Fosse]

Right. The jpeg compression itself can change values, since the chroma component is compressed even more aggressively than the luminance component.

Proof should always be kept off! It has no place in a normal workflow. It is only used as a final check for clipping in a print profile.

Converting to a different profile will change the numbers. Don't do it unless you need to. As long as you stay in the same color space and use a non-destructive file format, numbers will not change.

[Dynamic Office]

Just out of curiosity, would anyone know the reasoning behind the printers wanting it in RGB?

[Test Screen Name]

Most printers these days would, I think, want RGB, because they can do a much better job of converting to their specific mixture of inks. This mostly happens inside the print workflow automatically. People who send in CMYK frequently don't have enough understanding of CMYK colour issues, choice of profiles and rendering intent and so forth. Some printers use other ink mixtures than CMYK, too: sending them CMYK is a disaster for quality.

[andreamaestri]

Hi Sarah,

If your printer said to leave RGB because they problably want to convert it to CMYK during the printing stage. However, sRGB is only for web usage, and might not be the best option to use, it scales up everything to a broader colour range that not all devices supports.

[Bob_Hallam]

One thing to remember about changing color profiles is that you can go to a smaller space by converting to sRGB from say a larger color space like Adobe 1998 but not the other way around.  Once the color space is clipped it can't be expanded back out to the larger space.  So do pick a large enough RGB color space for your needs and the convert to any smaller spaces like sRGB or CMYK from that large working space.  Adobe RGB or ProPhoto are good choices for a working space.   ProPhoto is great if you are planning to go to a wide gamut printing process like a fine art print with very bright colors.