Talk about the many color modes of Photoshop (one)
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RGB, CMYK, LAB, HSB... Maybe many of my friends have seen these color modes, but do you know them? Most of my friends will say no. Color mode is the most basic knowledge of graphic design. How can I not master it? Each mode has its own advantages and disadvantages, and has its own scope of application. Let me talk to you about these color modes in detail.
1, RGB mode
RGB is the color mode of the color light. R stands for red, G stands for green, B stands for blue, and three colors superimpose to form other colors. Because the three colors have 256 levels of brightness, the three colors add up to 16.7 million colors. That is true color, through them enough to be in the beautiful world.
In RGB mode, other colors can be generated by superimposing red, green, and blue, so this mode is also called additive mode. Many devices, such as displays, projection devices, and televisions, rely on this additive mode.
In terms of editing images, the RGB color mode is also the best color mode because it provides a full-screen 24-bit color range, ie true color display. However, if the RGB mode is used for printing, it is not optimal, because some colors provided by the RGB mode are out of the range of printing, so when printing a true color image, it will inevitably lose a part. Brightness, and brighter colors are definitely distorted. . This is mainly because the CMYK mode is used for printing, and the color defined by the CMYK mode is much less than the color defined by the RGB mode. Therefore, when printing, the system automatically converts the RGB mode to the CMYK mode, which inevitably loses a part of the color and appears to be printed. Post-distortion phenomenon.
2, CMYK mode
When the sun shines on an object, the object absorbs a portion of the light and reflects the remaining light. The reflected light is the color of the object we see. This is a subtractive color mode and is also fundamentally different from the RGB mode. Not only do we use this color reduction mode when looking at the color of the object, but also the color reduction mode applied when printing on paper.
According to this subtractive mode, a CMYK color mode suitable for printing is derived.
CMYK stands for four colors used in printing, C for cyan, M for magenta, Y for yellow, and K for black. Because in actual references, cyan, magenta, and yellow are difficult to stack to form true black, but at most it is brown. Therefore, K - black was introduced. The effect of black is to strengthen the dark tone and deepen the dark color.
CMYK mode is the best print mode, and RGB mode cannot be completely printed despite its many colors. So is it CMYK mode when editing? No, the reasons are as follows:
Editing with CMYK mode can avoid color loss, but the operation speed is very slow. Mainly because: 1. Even if working in CMYK mode, Photoshop must change the CMYK mode to the RGB mode used by the display. 2. For the same image, RGB mode only needs to process three channels, while CMYK mode needs to process four feeds.
Since the scanner and display used by the user are both RGB devices, there is a process of converting the RGB mode to the CMYK mode whenever working in CMYK mode.
Therefore, whether to apply CMYK mode for editing is a problem of conversion in RGB mode and CMYK mode.
Give me a suggestion here, it can be regarded as my experience. First edit in RGB mode, then print in CMYK mode, convert before printing, and then add the necessary color correction, sharpening and rest. This makes Photoshop slower in CMYK mode, but saves most editing time.
In order to quickly preview the display of images in CMYK mode, you can use the CMYK Preview command under the View menu without converting the mode.
This mode conversion before printing is not the best way to avoid image loss. The best method is to use Lab mode and CMYK mode to minimize image distortion. The Lab mode is described below.
3, Lab mode
The Lab mode is a color model published by the International Commission on Illumination (CIE) in 1976.
You already understand: RGB mode is a color-increasing mode of a luminescent screen, and CMYK mode is a color-reducing printing subtractive mode. So, what is the processing mode of Lab?
Lab mode is neither dependent on light nor pigment. It is a color pattern determined by the CIE organization that theoretically includes all colors visible to the human eye. The Lab mode compensates for the deficiencies of the RGB and CMYK color modes.
The Lab mode consists of three channels, but not the R, G, and B channels. One of its channels is brightness, which is L. The other two are color channels, denoted by A and B. The A channel includes colors from dark green (bottom brightness value) to gray (middle brightness value) to bright pink (high brightness value); B channel is from bright blue (bottom brightness value) to gray (middle brightness) Value) to yellow (high brightness value). Therefore, this color blend will produce bright colors.
The Lab mode defines the most colors, is independent of light and equipment, and is as fast as RGB mode, much faster than CMYK mode. Therefore, you can safely and boldly use the Lab mode in image editing. Moreover, the Lab mode is not lost or replaced when converted to CMYK mode. Therefore, the best way to avoid color loss is to use Lab mode to edit the image and then convert it to CMYK mode printout.
When you convert RGB mode to CMYK mode, Photoshop will automatically convert RGB mode to Lab mode and then to CMYK mode.
In the expression color range, the Lab mode is in the first place, the RGB mode is in the second place, and the CMYK mode is in the third place.