Thank you both for replying, Bob, I know this is a complex subject, but perhaps you can correct my view of what happens.
Taking a pixel (value a,b,c) in an image open in say photoshop. If the profile is say sRGB, then it's internal display value will change to say (r,g,b) - and this is the value that the info palette will display. The screen also maps values to display them correctly, and so I would then expect a further transformation to value (x,y,z). I assume when I read a pixel from the screen, I'm getting (x,y,z), but if I know the screen mappiong I should be able to get back to (r,g,b). Is this view hopelessly wrong? Thanks Chris ----- Original Message ----- From: "Bob Friesenhahn" <[EMAIL PROTECTED]> To: "Louis Solomon [SteelBytes]" <[EMAIL PROTECTED]> Cc: <lcms-user@lists.sourceforge.net> Sent: Monday, February 04, 2008 4:30 AM Subject: Re: [Lcms-user] Colour management via screen sampling > On Mon, 4 Feb 2008, Louis Solomon [SteelBytes] wrote: > > > I think when reading from the screen (eg GetPixel(screendc,x,y)) that you > > will always get values in the screen profile - which for unprofiled screens > > is sRGB. using GetICMProfile(screendc) you can get the name of the current > > screen profile - watch out for multi screen systems :-) > > Values taken from the "screen" are completely meaningless other than > how they cause that physical pixel to respond. sRGB is just an > average representation for early '90s vintage CRT displays, which are > hardly used any more. It is correct that if someone adjusts the image > based on what they see on the screen then the pixels are in the > "screen" profile. Otherwise the pixel values are essentially > meaningless. > > Bob > ====================================== > Bob Friesenhahn > [EMAIL PROTECTED], http://www.simplesystems.org/users/bfriesen/ > GraphicsMagick Maintainer, http://www.GraphicsMagick.org/ > > > ------------------------------------------------------------------------- > This SF.net email is sponsored by: Microsoft > Defy all challenges. Microsoft(R) Visual Studio 2008. > http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ > _______________________________________________ > Lcms-user mailing list > Lcms-user@lists.sourceforge.net > https://lists.sourceforge.net/lists/listinfo/lcms-user ------------------------------------------------------------------------- This SF.net email is sponsored by: Microsoft Defy all challenges. Microsoft(R) Visual Studio 2008. http://clk.atdmt.com/MRT/go/vse0120000070mrt/direct/01/ _______________________________________________ Lcms-user mailing list Lcms-user@lists.sourceforge.net https://lists.sourceforge.net/lists/listinfo/lcms-user
