Why do calculated and read-out RGB-Values differ?

Question

In short:

1. Generate Mesh and choose color in color picker for the whole mesh (The mesh in the example below is a simple cube)
2. Read color (three float values) via Python and send them (with mesh details and uv-map ect) to a C++-Application
3. C++-Application creates a image which should be used as a texture

Problem:

The color, which is shown in the color picker isn't the same as the color of the texture.

I use the three float values, calculate the values between 0 and 255 and set the rgb-channels. Then the image is saved.

Some Screenshots:

color picker with rgb

RGB-Values via GIMP:

• R = 184
• G = 119
• B = 255

RGB-Values calculated and rounded: (255 * value)

• R = 0.479 * 255 = 122
• G = 0.184 * 255 = 47
• B = 1.0 * 255 = 255

They aren't the same?

Generated Texture

RGB-Values via GIMP:

• R = 122
• G = 47
• B = 255

Renderen with Blender Cycles

And now a Screenshot from the Mesh + Texture rendered via Cycles (with Ambient Occlusion). I removed the default lamp because I wan't to get a clean output.

RGB-Values of the color picker via GIMP (same as above):

• R = 184
• G = 119
• B = 255

RGB-Values of the cube via GIMP:

• R = 125
• G = 48
• B = 255

What is the problem?

PS: I didn't know which tags I should use for this question. So please remove or add tags if you think that would be better. Thanks!

Answer 1

The values differ because the rgb-values of the color picker aren't gamma corrected.

If I correct them like answered here https://stackoverflow.com/a/17910665/3069477 the colors are matching. I still get different RGB-Values but the difference is really small (rounding error).

Resulting Screenshot:

Thanks @someonewithpc!