Printing. Printing is done in the CMYK color space. Cyan, Magenta, Yellow, blacK. When you print in color, it is basically four different printers printing onto

Printing. Printing is done in the CMYK color space. Cyan, Magenta, Yellow, blacK. When you print in color, it is basically four different printers printing onto the same piece of paper. Ideally everything is all lined up correctly, but if you want to do it on an industrial scale, good alignment costs time and money. Big printed color color posters tend to have shitty alignment. A color tag needs to have good alignment; if the cyan, magenta, yellow print runs are misaligned, chances are a color tag won't be able to read it. But the black run is always aligned to the black run. So it will always work. Lighting. The Sun, incandescent, and halogen lights have pretty good color reproduction. But LED lights and fluorescent lights do not. LED lights and fluorescent lights are designed to look acceptable to human eyes. And they can be reasonably good at it. But cameras are not human eyes; color gets all fucky when you look at it through a camera. Cameras. The tag you linked to uses the LAB color space; one channel is brightness, one channel is blue vs yellow, one channel is red vs green. Cameras almost always have BGGR arrays; on a 4 megapixel camera, you will have 1 million blue pixels, 2 million green pixels, and 1 million red pixels. So if you use a normal camera to read a tag in the LAB space, you have 4 million pixels reading the brightness channel, 3 million pixels reading the red-green channel, and 1 million pixels reading the blue-yellow channel.