Scanners and digital cameras areDigital Printingthe main equipment for image input in the middle is to correct their brightness, contrast, black and white field (the balance of RGB primary colors), so that the scanner can scan the same original at different times to obtain the same image data, or digital The camera can obtain the same image data by shooting the same scene multiple times.

Scanners and digital cameras use the RGB additive color method for the reproduction of the original color. During the scanning or imaging process, color information must be recorded through spectral separation and photoelectric conversion. Whether the scanner can faithfully reproduce the color gradation in the image is the key to the success of digital printing. Most scanners have been calibrated at the factory, but due to differences in manufacturing conditions, changes in the color temperature of the light source, the degree of old and new, etc. will affect the scanner index. Therefore, it is very important to correct and characterize the scanner. The variables to be corrected by the scanner mainly include brightness, contrast, gamma, and white balance. The emphasis is on the correction of white balance, so that the neutral gray area of the scanned image can get the same RGB three-channel signal to ensure the correct color of the input system. Many scanners now have a self-calibration function or built-in correction software, which can directly perform white balance processing, or you can observe the RGB value of each level on the gray scale by scanning the gray scale and adjust it to a close or consistent effect. Due to changes in the sensitivity of the scanner and the color temperature of the light source over time, the changes will be reduced. Therefore, after working for a period of time, you should do a characterization and re-create a new feature file to ensure the correctness of the scanned color.
The method of calibration and characterization of the scanner is: in the test state, first scan and input the projected or reflected color code that conforms to the ISO IT8 standard, and the color code is accompanied by a floppy disk containing the color measurement value file of the color block, the file is in text format Storage, called "IT8 data reference file". Then, use the corresponding software to distinguish the relevant color space used in the color copy process of the scanner. After the software analyzes and compares the scanned image with the original data of the color standard, the corresponding relationship between the color space and the standard color space is analyzed. Finally, this information is stored in an electronic file to produce a "scanner color profile".