Colour Watcher - Screen and Profile colours
When I wrote my first Watcher (in 2007), I asked if it was possible to deduce the image values from the screen values and was told it was not achievable. However I thought I would experiment a bit and see what I could deduce.
So I started with coloured gradients and got the Watcher to automatically read and record the (screen) values. [The white blob is to position the mouse before starting the 7 scans].
I could therefore plot the difference between the actual RGB values in the image and what was displayed to us on the screen - I'll call them the visual colours - because the Watcher reads screen values.
Just to state the obvious, a colour profile takes the channel values in the image and modifies them before displaying the colours on the screen. Profile aware programs, such as Photoshop, modify the image values (according to the embedded profile) and others, such as most browsers, do not (or assume a fixed profile). I think of it rather like a wysisug word processor, sometimes you see the raw text and at other times the formatted view. And just to make matters worse, with the exception of the Lab Colour space (and Munsell), all colour spaces are device dependent and not 'absolute'.
What I did not realise is that Photoshop does not always give you what you expect and it took me two painful weeks to get meaningful results and then only with the help of Mike Russell (of CurveMeister fame) - see here.
Let me show you what I discovered and perhaps it will blow your mind as it did mine. I will zig-zag the text across the page, showing the file values on the left and the visual (Photoshop) ones on the right.