Is RGB on Mac something else as RGB on windows?

[Tiemo Hollmann TB]

Hello,

I have an application, where I manipulate an image. I exchange a specified
RGB color by another value. I developed this app on windows and everything
works fine. Now at final testing my function seems to be broken, because the
same image (a screenshot taken from a video) seems to have other RGB values
on a Mac, so that the exchange doesen't work anymore on a Mac.

 

I tested to create a png with photoshop on Windows with a blue color
100,150,200. Opening this png on my Mac and picking the color it gives me:
83,131,185. Isn't RGB = RGB on different platforms? That the same RGB might
display different on different monitors is clear, but a different RGB value?

 

I am just puzzled because I don't know where to start researching, what is
the source of my issue. Is it just Windows/Mac or could this RGB value also
differ on each monitor? If yes, how could I define, which color is to be
exchanged?

 

Any insights, whats going on here welcome

Tiemo