Legacy ImageMagick Discussions Archive

I'm not quite sure what you are asking, but the following might answer it. When Q16 (or Q32 or Q64) IM reads an 8-bit/channel/pixel image, values are expanded to fit the Q. Ths is NOT done by simply shifting bits, because we want 0->0 and 255->65535. It is done by replicating bytes, so an input 8 ...

I'm using a pixel cache to modify PixelPacket struct for each pixel in a Bitmap which is synced before writing. The image I'm editing has a color depth of 8 and my version of Magick++ is using a MagicQuantumDepth of 16. I open the image and in the first 10 pixels I modify the RGB color values. It ...