A project for an image processing Cocoa app last year ran into some difficulty when images produced had small color differences compared to the results of previous versions. We had changed most of the infrastructure as we ported this former Photoshop plug-in. We had to consider many systems as possible culprits. Did the colors shift on loading? During format conversion? During processing? Converting for display? Or when saved to disk? Did the format of the image file matter? Did Photoshop do something Cocoa wasn’t doing? It was a slog, but that last one proved to be the right question.