Is it wrong the color displayed in channels panel?

[gogoend]

Hello~

I fill a rectangular with color rgb(127, 127, 127) on the canvas, then open the channels panel. When I use my screen color picker to measure the color in the thumbnail, I find that the color component displayed in thumbnail is different from the original one. For example:

I think the color components in every channel should be 127 which is from the origin color, but now their value is 159.

Why does this happen?

In addition, it's seems right in After Effects when viewing single channel as the following screenshot:

[gogoend]

haha, I find the reason. I selected a wrong color profile...

[D Fosse · Accepted solution]

Yes, that's the explanation. Individual channels are grayscale images, displayed in your working gray. This doesn't necessarily have the same tone response curve as the document RGB profile, so the numbers change.

To avoid that, set a working gray that has the same tone curve as document RGB:

sRGB > sGray

Adobe RGB > Gray Gamma 2.2

ProPhoto > Gray Gamma 1.8

[TheDigitalDog · Accepted solution]

Not sure what you mean by "Screen Picker". If this is something like Apple's Digital Color Meter utility** or similar to 'measure' color, it can't tell you anything about the actual color numbers of documents inside say Photoshop. 

**This is not measuring anything. It is taking two or three bits of information:
1. The color that an app is actually outputting to a pixel. i.e. an RGB level.
2. The colorspace that the app says should be used for that pixel for ColorSync to correctly display it (defaults to sRGB if the app doesn't specify).
3. The ICC profile associated with the display.

For this reason, a mismatch in numbers is expected.