Customized ICC Scanner Profile Construction and Concerns

摘要

The main concept of using scanners is to convert an analog hard copy image into digital form and then exchange its data across different media, such as displays or printers. As each color device can reproduce a different amount of color, which can be defined as its color gamut, it is essential to have a reliable color reproduction across these devices. This can be controlled by constructing an ICC profile for each device based on ICC (International Color Consortium) standards that assist the Color Management Systems' (CMS) ambition of achieving consistence color transformation and appearance across color media. Accurate color transformation from a device-dependent color space (RGB or CMYK) to a standard color space or device-independent color space (LAB or XYZ), as defined by the CIE (Commission Internationale de L'Eclairage), starts with efficient colorimetric color characterization of each device and thus an efficient ICC profile. The focus of this paper will be on characterizing scanner devices.First this paper studies and evaluates existing scanner characterization methods. A new and enhanced colorimetric characterization model is proposed. The method was assembled based on the previous evaluation results. The goal is to estimate a smooth transformation function whose derivatives are continuous, which reflects a smooth scanner device gamut. A transformation LUT (look-up table) was then built using these resulting values from the new characterization method. The built LUT was then stored inside a newly constructed scanner profile, which was achieved by using a customized C++ program code as our profile editor. The new method was applied on different scanners and the AE error was computed to evaluate the accuracy of the characterization.