NSColor RGB color calculation

Question

I'm using the sip developer tool to get a specific color from this image:

(The right side bottom section gray).

Sip returns:

[NSColor colorWithCalibratedRed:0.96 green:0.96 blue:0.96 alpha:1]

Which is in RGB: RGB(226, 226, 226)

However, when I use this myself in code, the background color in my app (when checking with sip) is RGB(232, 232, 232)

Does anyone know why there is such a difference?

I've also tried to calculate it manually from RGB by dividing by 255.0 - same problem.

I have the same issue with other colors, plain solid colors too..

Sounds like this sip developer tool is broken then. I would assume the issue is with colour spaces: developer.apple.com/library/mac/documentation/Cocoa/Conceptual/… — trojanfoe
– trojanfoe, Commented Jan 28, 2014 at 14:04
This is probably a colour space thing (I can't find the word) but I'd guess that the value it is using to calculate the colours is not calibrated the same way as the input you're using to set the colours in the first place. — Fogmeister
– Fogmeister, Commented Jan 28, 2014 at 14:04
Are you on a Mac. If so use the DigitalColor Meter. With DigitalColor Meter I get a textured colour around 222-226. — Fogmeister
– Fogmeister, Commented Jan 28, 2014 at 14:25
@Fogmeister - which one should be used, generic RGB, or sRGB? — user429620
– user429620, Commented Jan 28, 2014 at 14:28
@Wesley You're making something that will be used on multiple computers with different displays and different configurations and in different light settings. Just use whichever you like the look of most. However, a 2% colour change isn't going to be noticed by most people. — Fogmeister
– Fogmeister, Commented Jan 28, 2014 at 14:39

Fogmeister · Accepted Answer · 2014-01-28 14:52:20Z

This is probably a colour space thing. I'd guess that sip is not calibrated or calculated the same way as the NSColor function.

Anyway, if you use DigitalColor Meter you should get the same colours out as the colours that you put in.

As it's a native app I feel I can rely on its results more than I would a third party app.

Also I think your calculation is off slightly. 0.96 is actually 245 not 226.

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