Talk about Photoshop's many color modes (1)

RGB, CMYK, LAB, HSB... Perhaps many of my friends have seen these color modes, but do you understand them? Most of my friends will not understand it. Color mode is the basic knowledge of graphic design. Each mode has its own advantages and disadvantages, and has its own scope of application. I will talk about these color modes in detail below.

1, RGB mode

RGB is a color mode of color. R stands for red, G stands for green, and B stands for blue. Three colors are superimposed to form other colors. Because three colors have 256 levels of brightness, overlaid three colors form 16.7 million colors. That is true color, through them enough in the beautiful world.

In RGB mode, other colors can be generated by superposition of red, green, and blue, so this mode is also called additive mode. Many displays, projection devices, televisions, and many others rely on this additive mode.

In terms of editing images, the RGB color mode is also the best color mode because it can provide a full-screen 24-bit color range, ie true color display. However, it is not optimal to use the RGB mode for printing, because some of the colors provided by the RGB mode are out of the range of printing, so when you print a true-color image, you will inevitably lose some of it. Brightness, and more vivid colors will certainly be distorted. . This is mainly because the printing uses the CMYK mode, 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 results in the loss of a part of the colors. Post-distortion phenomenon.

2, CMYK mode

When sunlight strikes an object, it absorbs some of the light and reflects the rest of the light. The reflected light is the color of the object we see. This is a subtractive color mode, which is also fundamentally different from the RGB mode. Not only do we use this subtraction mode when we look at the color of an object, but we also apply this subtraction mode when printing on paper.

According to this subtractive mode, the CMYK color mode suitable for printing is evolved.

CMYK stands for the four colors used for printing, C for cyan, M for magenta, Y for yellow, and K for black. Because in actual citations, cyan, magenta, and yellow are difficult to superimpose to form true black, but at best it is only brown. Therefore, the introduction of K - black. The role of black is to enhance the dark tone and deepen the dark colors.

The CMYK mode is the best printing mode. Although the RGB mode has many colors, it cannot be completely printed out. Is it the CMYK mode that is used when editing? No, the reason is as follows:

Editing with CMYK mode can avoid color loss, but the operation speed is very slow. Mainly because: 1. Even when working in CMYK mode, Photoshop must convert the CMYK mode to the RGB mode used by the monitor. 2. For the same image, the RGB mode only needs to handle three channels, while the CMYK mode needs to handle four feeds.

Since the scanners and displays used by users are all RGB devices, there is a process of converting RGB mode to CMYK mode whenever working with CMYK mode.

Therefore, whether or not to apply the CMYK mode for editing is a matter of converting between the RGB mode and the CMYK mode.

Here's a suggestion. It's also my little experience. First use the RGB mode for editing work, and then use the CMYK mode for printing. Only perform the conversion before printing, and then add the necessary color correction, sharpening, and rest. This saves most of the editing time, although it makes Photoshop slower in CMYK mode.

In order to quickly preview the display effect of the image in CMYK mode, you can use the CMYK Preview command in the View menu without converting the mode.

This pre-print mode conversion is not the best way to avoid image loss. The best method is to use Lab mode and CMYK mode in combination to minimize image distortion. The Lab mode is described below.

3, Lab mode

The Lab model is a color model announced by the International Commission on Illumination (CIE) in 1976 (wow, far away.).

You already understand that RGB mode is an additive mode of a luminescent screen, and CMYK mode is a color-reduced print reduction mode. So, what is the processing model of Lab?

The Lab model neither depends on light nor on pigments. It is a color model defined by the CIE organization that theoretically includes all colors that the human eye can see. Lab mode compensates for the lack of both RGB and CMYK color modes.

Lab mode consists of three channels, but not R, G, B channels. One of its channels is brightness, which is L. The other two are color channels, denoted by A and B. The color included in channel A is from dark green (bottom luminance value) to gray (middle luminance value) to bright pink (high luminance value); B channel is from bright blue (bottom luminance value) to gray (medium luminance Value) to yellow (high brightness value). Therefore, this color blend will produce bright colors.

Lab mode defines the most colors, and is independent of light and device and the processing speed is as fast as RGB mode, much faster than CMYK mode. Therefore, it is safe to use the Lab mode in image editing. Moreover, Lab mode does not lose or replace color when converted to CMYK mode. Therefore, the best way to avoid color loss is to use the Lab mode to edit the image and convert it to CMYK mode printout.

When you convert RGB mode to CMYK mode, Photoshop automatically converts the RGB mode to Lab mode and then to CMYK mode.

In the expression color range, the Lab pattern is the first, the RGB mode is the second, and the CMYK mode is the third.