Photoshop colour manipulation without overlapping/channel question/blending question

[CharlieHarris]

I'm somewhat experienced in Photoshop although I am still learning about colour manipulation. I have a problem that I cannot figure out how to solve, I'm hoping it's easy!

In a nutshell, I want to change the green in this image to a very specific blue hex code. I want to change the beige in this image to another very specific beige hex code. And I want to to select the gold areas and change it to another specific hex code, and i don't want any other pixels affected. essentially, only letting a pixel belong to one channel, not overlapping, if that makes sense?

I've managed to do that by duplicating base layer and going to image > adjustments > desaturate, then selecting colour range > highlights > creating layer with that selection > new fill layer > clipping mask > set blend mode to colour. then doing the same colour range for midtones and shadows.

it sort of works. but due to the transparency, certain layers are affecting the colour cast of the final output. for instance, the blue hex code i use for the green area in that image, isn't right, it's more turquoise, clearly being affected by lower layers. swapping the layers around just affects another colour.

I've tried subtracting layer sections from the last, but it doesn't seem to work (or i'm doing it wrong). also, when I do that, i end up with no pixels selected. however, there's clearly still some pixels left as when i hide the base layers, there's transparency showing. 

i appreciate due to the tonal range of the image, there is transparency, and i want it to look natural, so i know there may be some blending, but i just don't know the best way to ensure the colours i am trying to manipulate are actually ending up the correct hex code or at least the hue for that hex code.

i also appreciate this may have made no sense, as it's pretty obvious i still have learning to do on this!

any help would be great, thank you 🙂

[Chuck Uebele]

If I understand what you want, that would result in an image that looks posterized. Using color range, there will be some transitioning of feathering. To have no feathering, you might want to set the fuzziness all the way down. Then to be totally sure that no transparency has been selected, use the magic wand tool and select a known totally transparent area. Reverse the selection and use that for your mask for your solid color layer. Keep one color the entire image, or you will likely end up with transparent areas.