I have a picture where it is black, grey and white. I can change the color by going to image > adjustments > HUE

By doing that I got a little window where I can actually change lots of things

enter image description here

But it doesn't give me a true RGB value as I don't want any red and green in my color. It only display things from -100 to +100.

It is important to note that GIMP actually lets you do that fairly simply with the tool "colorify" in true RGB. I am utterly surprised photoshop doesn't propose that.

How can I do that?

  • \$\begingroup\$ I don't have the rep in this stack yet to vtc for a custom reason, but as it stands this question is not about photography, per se, but about image manipulation, which is off-topic. \$\endgroup\$
    – Tetsujin
    Dec 10, 2017 at 18:09
  • 3
    \$\begingroup\$ Can you describe more what you are trying to do? This sounds like it might be an "XY problem". \$\endgroup\$
    – mattdm
    Dec 10, 2017 at 19:26

2 Answers 2


If you have a monochrome image and want to apply color to it, like in the gradient below, you can't do this with a Hue/Saturation adjustment.

blue gradient

You can however obtain this much easier: add a new layer, fill it with the color you desire (RGB (0, 0, 255) was used in the above example) and set its blend mode to Darken.

  • \$\begingroup\$ thank you for your answer. I will try to apply it right away \$\endgroup\$ Dec 13, 2017 at 18:11

RGB is a color space, but with dimensions of a red primary, green primary, and blue primary, it is not one which has any inherent notion of lightness, saturation, or hue. To make adjustments to things like those, you have to work in a different color space, like L*a*b* or L*u*v*.

I do not understand what you want to do; you have a monochromatic image, and a performing a hue adjustment on it? Are you trying to produce a sepia-like effect?

  • \$\begingroup\$ Hello @Brandon, actually I have an image with grey colors yes. WHen I change the HUE I can change the grey into a color. I would like to HUE it in blue but without any red or green. But as it doesn't give me any RGB hint I do not know which blue to add. And I tried many things but couldn't find how to actually HUE my image without any other color except blue. \$\endgroup\$ Dec 10, 2017 at 22:40
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    \$\begingroup\$ What do you mean by "grey" colors? Is the image mode grayscale? RGB? CYMK? Colors are, by their very nature, not grey. If the image mode is RGB, you can do a hue adjustment and then paint black over the entire R and G channel to make it a grayscale image in the blue primary, but that may not be the shade of blue you want. Most shades of blue require a combination of B + R and/or G. \$\endgroup\$ Dec 10, 2017 at 22:42
  • \$\begingroup\$ yes I see. Well it is a RGB greyscale so when I change the HUE it changes colors. So does that mean that I can't have a pure blue colors with changing the HUE ? In gimp you can do it very easily with the "colorify" mode. Wanted to know if photoshop had something similar. \$\endgroup\$ Dec 12, 2017 at 7:58
  • \$\begingroup\$ So do you want an image that spans [0,0,0] -> [0,0,255] in [R,G,B]? \$\endgroup\$ Dec 12, 2017 at 16:09
  • \$\begingroup\$ Hi @Brandon Yes something like that. I would like to change the color in blue without any green or red. Like the gimp colorify tool that lets you adjust RGB. In photoshop I can't seem to find this as it is wrote like that: -100 - 0 - +100 \$\endgroup\$ Dec 13, 2017 at 16:51

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