Technology Incorporated into Our Total Color Management System
In recent years, various workflows are changing so that the work centers around electronic displays. For example, in workflows starting with product development and ending in sales promotion, the information being handled is increasingly becoming digitized, which means that not only printers, but also devices that use RGB data, such as low-price displays, large displays, projectors, and digital signage, are being used as tools to communicate information. However, the colors of RGB data are reproduced very differently on different displays. Therefore, the colors that a designer originally intended may not be accurately communicated, resulting in color inconsistencies which could require design rework or diminish the brand.
For example, when a product is designed, the colors that appear on the display used by the designer are considered to be the original colors of the product. However, since the color characteristics of each device are different, when an image of the product is displayed on other devices, such as large displays, or printed with a color printer, the product's colors will appear to be different from the original colors. In order to prevent this issue from occurring, some measures, such as using the same model of display throughout all phases of the workflow, have been taken. Unfortunately, this is not a realistic measure, as it limits the size of the displays that can be used. Also, even if all the displays used were of the same model, there are still large differences between individual displays and between different manufacturing lots, so the colors still would not match sufficiently. What is necessary is a total color management method, in which colors are consistent between different displays and between displays and printers.
Many of the existing color-correction technologies for electronic displays involve linear matrix color conversion using software. This method can only match the colors between a very limited range of devices. Therefore, in the case of low-price displays, large displays, and projectors, which are nonlinear devices with low additive mixingNote1 capabilities, it is not possible to calibrate colors with high precision using this method, and it may even worsen the color gap instead. Also, the color gamutNote2 of displays is significantly different than that of printers (Fig. 1). Therefore, when using the existing method, which minimizes the color differences between displays numerically, it is not possible to represent color tones on displays with a small color gamut, meaning that colors will not be reproduced accurately on these displays.
To address these issues, Fuji Xerox developed color-correction technology using a multidimensional lookup table (LUT) that features three technologies: "device characteristics modeling," "gamut mapping," and "device management." This LUT has led to the development of a total color management system that allows for the consistent reproduction of colors between various display devices.
Fig. 1: Color gamut differences between different printers, and between displays and projectors
Using the previous method of numerically minimizing the color difference between displays does accurately represent the color tones of the original image.
Fig. 2: Example of an issue that occurs when the method of numerically minimizing the color difference between displays is used
In addition, since the color space of a display is determined based on the color white, if the white is not accurately calibrated, the entire color space may be incorrect. Therefore, controlling the white in the color space becomes extremely important when matching colors between displays.
Therefore, in "device characteristics modeling," a model is created so that the areas of the color spaces with high nonlinearity are corrected with higher accuracy, so as to improve the tone reproduction of the displays, which is important in displaying colors that viewers consider consistent. Furthermore, in "gamut mapping," an original algorithm is used to convert colors so that they match between devices with large differences in their color spaces. Such technology prevents color inconsistencies, blocked up shadows, and blow out highlights from occurring and offers more flexible color conversion that suits customer workflow and needs. As a result, colors can be reproduced more accurately on any device, even across devices with very different color characteristics, such as low-price displays and large displays.
Finally, in "device management," the environment surrounding the displays, such as ambient lighting and various characteristics of the devices, is analyzed to determine the color conversion method. This technology is able to consistently reproduce colors across the various devices in a customer's workflow, such as displays, printers, and projectors, optimizing the customer's "color environment."
Blocked up shadows
Through using our technology to provide a color environment that is consistent across various display devices, we can prevent declines in customers' productivity due to differences in how colors appear on different devices, and help customers achieve a new, speedier workflow by allowing them to accurately digitize the information they handle.
- Note1 Additive mixing: Reproduction of colors by combining the three colors of light (R, G, and B).
- Note2 Gamut: The subset of colors that a device is able to represent.