Development of a method for using color in machine-readable optical codes to increase the information capacity

The possibility of increasing the capacity of QR codes by using color modules without adding new metadata is studied. A method for automatically determining the number of colors and their palette using image processing is proposed, which ensures compatibility with classical QR codes. A system is proposed that allows creating a QR code that uses 4, 8 or 16 colors in addition to the standard black and white version. The main problem is the optimal use of the available color space to minimize errors when reading an informative image with an optical camera, compensate for the effects of uneven lighting and poor image quality, and ensure backward compatibility with the black and white version. In the course of analyzing the use of different color spaces, the most promising perceptually uniform OKLCH space was determined. Algorithms for image preprocessing for correct decoding of information and an algorithm for encoding and decoding information using color have been developed. The results obtained are explained by the distribution of the color gamut after the test reading of informative images, the number of errors and successful readings. Using the OKLCH color space, it was possible to read 60% of 16-color test images, while in HSL it was not possible to read any image due to color overlap. However, both spaces have a fairly high rate of successful reads in 4 and 8 color codes. The use of color will allow the introduction of new standards for high-capacity color machine-readable codes without requiring changes to existing ones for additional metadata, while maintaining full backward compatibility and reliability of black and white codes. Increased information capacity in some cases allows to eliminate the need to be connected to the Internet, reduce the size of the code, and make it more visually appealing by using colors.