What needs to be clear is that there will always be a difference between the color displayed on the computer monitor and the actual printed color. The only thing we can do is to minimize this difference. This involves many reasons: image material, color mode of design software , Display color accuracy, printing equipment quality and ink quality, etc. First, let's start with the color mode. 1. RGB mode:
The RGB mode is composed of three colors of red, green, and blue light. It is mainly used in computer monitors and TV screen displays, so it is also called color light mode.
The light of each color light is divided into 256 levels from 0 to 255. 0 means that there is no such light, and 255 represents the most saturated state of this light, thus forming the RGB color light mode. When R = G = B = 0, that is, when all three color lights do not emit light at the same time, it becomes black. The three light rays add up in pairs to form blue, fancy, and yellow. The stronger the light, the brighter the color. Finally, when R = G = B = 255, that is, when all three colors are illuminated at the same time to the brightest, it becomes white, so the RGB mode is called additive color method. 2. CMYK mode is composed of four color materials: cyan, product, yellow, and black. It is mainly used in printers and printing presses, so it is also called color material mode. The usage of each colorant ranges from 0% to 100%. Since the three CMY colorants can be mixed to produce many colors, the colors formed by adding them together are exactly the three colors of R, G, and B. Since the three CMY color materials cannot form pure black during printing and printing, a separate black color material K is required to form the color material mode of CMYK. The larger the amount of pigment, the heavier and darker the color; on the contrary, the smaller the amount of pigment, the brighter the color. Where there is no color material, what you see is white paper with nothing printed, so the CMYK mode is called subtractive color method. 3. Lab mode Lab mode is a theoretical mode for recording the color of light. It has the widest range, as long as the human eye can see the color mapped by visible light, Lab includes it. 4. The color gamut relationship of the three modes: Lab mode> RGB mode> CMYK mode. From this color gamut relationship, we can see: The color gamut of RGB is smaller than Lab, which means that not all colors can be displayed on the monitor. . The color gamut of CMKY is smaller than RGB, but some colors in CMYK are outside of RGB. This also tells us that certain printed and printed colors cannot be correctly reflected on the monitor. In RGB mode and CMYK mode, a considerable part of the color gamut of the two colors overlaps, and only the overlapped part is the color gamut that can be expressed by the display, printer, and printing machine.
In actual work, all of our printing machines are in CMYK mode, and the printers and printing machines will automatically convert the RGB color value to the closest CMYK value when working. But when converting RGB color values to CMYK values. This conversion causes a significant color difference between the printed color and the displayed color. Excluding the error of all external factors such as printers, monitors, etc., this color difference still exists.
When the picture (photo) you choose is processed into a very satisfactory color on the monitor, the color must be within the RGB color gamut, but it just happens to be outside the CMYK color gamut. Printing does not reflect part of the RGB color gamut normally, and the color difference printed is even greater. This is why we often complain about the difference between the color (picture) seen on the monitor and the color (picture) seen by the printer. The upper half of the image is the standard RGB three colors, and the lower half is the change after conversion to CMYK. You can do this experiment yourself: first fill in three color blocks in the RGB image: R255, G255, B255, and then press Ctrl+Y continuously to switch between RGB and CMYK modes and observe the difference .
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