What are the differences between various color modes in ps?

What is the difference between the following color modes:

1.RGB color mode?

This is the most commonly used mode in Photoshop, also known as true color mode. The image displayed in RGB mode has the highest quality. So it has become the default mode of Photoshop, and many effects in Photoshop need to be in RGB mode to take effect.

The RGB color mode is mainly composed of three basic colors of R (red), G (green) and B (blue), forming three color channels of red, green and blue. Each color channel contains 8-bit color information, and each information is represented by a brightness value of 0~255, so these three channels can produce more than16.7 million different colors together.

Therefore, when printing an image, you cannot print an image in RGB mode. At this time, it is necessary to change the RGB mode image to CMYK mode. If an image in RGB mode is converted, color loss or color cast may occur. ?

Second, HSB mode?

The establishment of HSB mode is mainly based on the way of human perception of color. The human eye can't distinguish the proportion of each primary color in RGB mode, but can only distinguish the color type, saturation and intensity. According to this characteristic of human eyes, the color of HSB forms an intuitive method, which can be directly distinguished by human eyes. It mainly regards color as composed of hue, saturation and lightness.

Among them, these three elements all describe different meanings. For example, hue refers to different color distinguishing features given by different wavelengths, such as red and green have different hue values; Saturation refers to the depth of color, that is, the relative purity of a single pigment, such as red can be divided into deep red, magenta, light red and so on; Brightness is used to express the intensity of color and describes the ratio of the amount of reflected light to the amount of absorbed light. Click the horizontal black triangle in the upper right corner of the Color Function panel and select the HSB slider from the pop-up menu.

The HSB mode is represented by an angle of 0-360 degrees, rather than a percentage as we understand it, just like a big colored wind wheel. Every time it rotates a little, its color changes according to this circumferential angle. ?

Third, CMYK color mode?

This is also a common color pattern. When printing an image, its color mode must be converted to CMYK mode. Therefore, this mode is mainly used for industrial printing. The CMYK pattern is matched by subtracting four colors: C (cyan), M (magenta), Y (yellow) and K (black).

Therefore, four channels of cyan, magenta, yellow and black are formed, and each channel is mixed to form a variety of colors. It is worth noting that if these four solid colors are included in the printing, they must be 100% solid colors. For example, if black is not set to pure black when printing, the film will not be sent successfully when printing, that is, the image cannot be printed. Because many of Photoshop's filter effects can't be used in CMYK mode, RGB mode is generally used, and it will only be converted to CMYK mode when printing is about to start, and the color may change. ?

Fourth, the gray model?

The image in grayscale mode has only grayscale and no other colors. Each pixel is represented by 8-bit or 16-bit color. If the color image is converted to grayscale mode, all colors will be replaced by different grayscales. ?

5. Bitmap mode?

Bitmap mode uses black and white to represent the image, without gray and other colors, so it is also called black and white image. If you convert an image to bitmap mode, you should first convert it to grayscale mode. ?

6. Dual-tone mode?

As mentioned above, CMYK mode is always used in printing, that is, four-color mode, but sometimes images only contain two colors and their matching colors, so in order to save costs, two-color mode can be used. ?

Seven, Lab color mode?

Lab color mode is the built-in mode of Photoshop, and it is also the mode with the widest color range among all modes. Therefore, when converting RGB and CMYK modes, the system will first convert to Lab mode, and then convert to CMYK color mode. But in general, Lab color mode is rarely used. Lab mode consists of three channels: brightness (L), a (from green to red) and b (from blue to yellow). The range of a and b is-120~ 120.

Extended data:

Three-color light model (English: RGB color model), also known as RGB color model or red, green and blue color model, is an additive color model, which adds red, green and blue colors in different proportions to produce various colors of light.

The main purpose of RGB color model is to detect, represent and display images in electronic systems (such as televisions and computers), but it is also used in traditional photography. Before the electronic age, based on human perception of color, RGB color model has a solid theoretical support.

RGB is a device-dependent color space: different devices detect and reproduce specific RGB values differently, because color substances (fluorescent agents or dyes) and their individual response levels to red, green and blue vary from manufacturer to manufacturer, and even the same device has different time.

References:

Baidu encyclopedia -Adobe Photoshop