This data-set is used in research of color difference recognition. Dataset contains images extracted from functional markers, in these images there are differect QR-Code cells presented. Extracted area has total of 5 rows, where functional part of the marker, sensor ink, is on rows 3 and 4. - Black cells illustrate QR-Codes black cells (binary 1) - White (or no color) cells illustrate QR-Codes white cells (binary 0) - Colored cells (only on rows 3 & 4) appear in different intensity and they are considered as white cells (binary 0) intensity and color of colored cells vary as defined in filename. Image have been capture with iPhone 8 in varying conditions. Filename defines following, underscore (_) is used as separator - Filename always starts with text "sensor" - QR-code size in cells - Capturing distance in centimeters (if not measured then "X") - Color intensity in percentage and color channel (RGB or CMYK), for example 10G = 10% in Green channel and 20CM = 20 in Cyan and Magenta - Ambient light in LUX (if not measured then "X")