Experts please answer: What are the printing density and the field density?

Simply put, printing density is the ability of ink to absorb light. You know that printing is realized by the principle of subtractive color. For example, for yellow ink, its complementary color is blue, that is, it absorbs blue light in the light. Densitometer judges the amount of yellow ink by measuring the content of blue light reflected to human eyes. There is a color filter in the densimeter. When you measure yellow ink, the instrument will automatically switch to the corresponding color filter. When printing monitoring, it is necessary to measure the density values of different colors with a densimeter, such as the density value of yellow, which reflects the thickness and color depth of yellow ink and is the basis for judging color reproduction. Different colors have different standard density ranges, with black ink being the largest and yellow the smallest.