Replace Colour not working

[aminin625]

Hi there, thanks in advance if anyone can help with this. 
It worked perfectly the first time but now no matter what i do i can't get it to work again.
I am trying to change pure white (fffff) to off white (fcfcfa), and everytime i do it immediately changes my input of that off white to a different one, (fafafa). I know this may seem Extremely trival and particular, but I've already done a lot of work by the other white and will be a lot to go back and change. Each time I try, I check it by using the eyedropper tool on where I've changed and the first time it worked, now just won't. On top of this, each time I click the input to change to the colour I want if I see it has changed it, it changes the colour again like it's hitting shuffle everytime I click OK, never being what I put in and each being different than the last. So Weird!

But if I am changing any other colour than white, it stays on my input of fcfcfa just fine, I can make any other colour my off white no worries.
I'd accept it just won't work and stop being so confused Except for the way it did work the first time, throwing me off. Why would it work once and then just keep shuffling Different off-whites at me??

Using the layer overlays doesn't seem to ever effect the whites, either. Any other ways of changing my shade of white? Help! thanks.

[D Fosse · Accepted solution]

This is a very frequently asked question, and it is based on a misunderstanding of the word "color" as it is used in digital image processing.

In everyday language, "color" includes the light/dark component as well as the pure chroma component. In digital image processing, and color science for that matter, it does not. Color is completely separate from lightness. White is not a color. It's a lightness/luminance without any color.

In everyday language "brown" is a color. In color science that's a dark orange. Orange is the color component of brown.

In other words, the color replacement tool does exactly what it's supposed to do. If it didn't, and worked like you want it to, it would just be an ordinary opaque paintbrush!

All that said, the color replacement tool is a very coarse tool, completely unsuitable for serious precision work. I don't know who thought it up and thought it was a good idea. It's useless IMO. There are much better and more precisely targeted ways to do this, like a masked layer set to Color blend mode. That has the advantage that it can be adjusted as you go.