Hi, I have to read all the RGBA values of every pixel of an image on the disk, as tif, png, jpg I read the imageRep with imageRepWithContentsOfFile and get the RGBA values with "colorAtX: y:" It works quite well with png images with "non alpha premultiplied" bitmap format. In this case I get a bitsPerPixel = 32. But if I save the same image with Photoshop as TIF, I get an "alpha premultiplied" bitmap format and a bitsPerPixel = 24. But worst of all, all the alpha values are 1.0, while some of them is for sure 0.5. So I can't even calculate the original non multiplied RGB values.
My question is: how can I get the true original RGBA pixels values of any image? Actually I do: imageRep = [NSBitmapImageRep imageRepWithContentsOfFile:filePath]; texWidth = [imageRep pixelsWide]; texHeight = [imageRep pixelsHigh]; for(y = 0; y < texHeight; y++){ for(x = 0; x < texWidth; x++){ NSColor *pixelColor = [imageRep colorAtX:x y:y]; NSColor *rgbColor = [pixelColor colorUsingColorSpace: [NSColorSpace deviceRGBColorSpace]]; [rgbColor getRed: &rgba[0] green:&rgba[1] blue:&rgba[2] alpha:&rgba[3]]; } } Regards -- Leonardo _______________________________________________ Cocoa-dev mailing list (Cocoa-dev@lists.apple.com) Please do not post admin requests or moderator comments to the list. Contact the moderators at cocoa-dev-admins(at)lists.apple.com Help/Unsubscribe/Update your Subscription: http://lists.apple.com/mailman/options/cocoa-dev/archive%40mail-archive.com This email sent to arch...@mail-archive.com