Photoshop Color Mode Complete Manual
In Photoshop, the concept of understanding mode is important because color mode decides the color model of displaying and printing electronic images (Simple color model is a mathematical algorithm for expressing color), what is a pair of electronic images? The manner is displayed or printed in the computer. Common color modes include bitmap mode, grayscale mode, two-tone mode, HSB (indicating color phase, saturation, brightness) mode, RGB (representing red, green, blue) mode, CMYK (represents blue, magenta, yellow, black ) Mode, LAB mode, index color mode, multi-channel mode, and 8-bit / 16-bit mode, the image description of each mode and the principle of reproducing color and the number of colors that can be displayed are different. The color mode also affects the number of images and file size of the image in addition to the number of colors that can be displayed in the image. The channel mentioned here is an important concept in Photoshop, each of which has one or more channels, and each channel stores information of color elements in the image. The default color channel in the image depends on its color mode. For example, the CMYK image has at least four channels, which resides in representing cyan, magenta, yellow and black information. In addition to these default color channels, additional channels called the Alpha channel can be added to the image to store the selection as mask and edit, and a spot color channel can be added. An image sometimes reaches 24 channels. By default, bitmap mode, grayscale two-tone and index color images are still a channel; RGB and LAB images have three channels; CMYK images have four channels. First, the HSB mode HSB mode is defined based on the observation of the human eye. In this mode, all colors are described in color phase or tone, saturation, and brightness three characteristics. 1. The color phase (H) color phase is a color physical and psychological characteristics associated with the main wavelength of color. It is known from the experiment that the visible light of different wavelengths has different colors. Many wavelengths of light can form a variety of colors in different proportion, but as long as the wavelength is constant, the color is determined. Non-color (black, hundred, gray) does not exist, all colors (red, orange, yellow, green, green, blue, purple, etc.) are the properties of color appearance. They are all color phases, and sometimes the color phase is also called hue. 2. Saturation (S) saturation finger refers to the strength or purity of the color, indicating the ratio of gray components in the colored phase, expressed by 0% to 100% (solid color). 3. Brightness (b) The brightness is the relative light level of color, usually used with 0% (black) -100% (white) to measuring. Second, the RGB mode RGB mode is based on the mixing principle of three primary color light in nature, red (R), Green (G) and blue (B) 3 in the luminance value from 0 (black) to 255 (white). Assign it in each color order to specify its color. When the primary color of different brightness is mixed, 256 * 256 * 256 colors are produced, about 16.7 million. For example, a bright red may be a R value of 246, a g value is 20, and a B value is 50. When the brightness value of the three primary colors is equal, gray is generated; when the three brightness values are 255, pure white is generated; and when all the brightness values are 0, pure black is generated. When the color of the three color light is generally higher than the original color luminance value, the method of generating a color in the RGB mode is also referred to as a color light. Third, the CMYK mode CMYK color mode is a printing mode.
Four of these letters refer to Qing (Cyan), Magenta, Black, which represents four colors in the printing. The CMYK mode is in nature, but there is no difference in the RGB mode, but the principle of generating color is different, and the color light generated by the light source is mixed in the RGB mode, and in the CMYK mode, the light is taken to have different ratios C, M, Y, On the paper of the K ink, the partial spectrum is absorbed, and the light reflected to the human eye produces color. Due to C, M, Y, K, with the increase of the four components of C, M, Y, and K, the light reflected to the human eye will be less and less, the brightness of the light will get lower and lower, all The method of generating color in the CMYK mode is also referred to as a color light reduction. Fourth, the prototype of the LAB mode LAB mode is a standard for a measure of color by the CIE Association in 1931, which is redefined in 1976 and is named CIELAB. This mode solves the difference in color support caused by different displays and print devices, that is, it does not depend on the device. The LAB color is a color of the two color components A and B. The value of the L is 0-100, and the a component represents the spectrum of green to red, and the B component represents the spectral change from blue to yellow, and the value of A and B are -120-120. The color range contained in the LAB mode is the most widely, which can contain all the colors in the RGB and CMYK mode. The CMYK mode has the least colors, and some of the colors of the chopper on the screen cannot be realized on the print. V. Other color mode In addition to basic RGB mode, CMYK mode, and LAB mode, Photoshop supports (or processes) other color modes, including bitmap mode, grayscale mode, two-tone mode, index color mode and more Channel mode. And these color patterns have their special use. For example, the image of the grayscale mode is only a gradation value without color information; the index color mode although color can be used, but the color that can be used is really small relative to the RGB mode and the CMYK mode. Here, you will introduce these colors. 1. Bitmap mode bitmap mode uses two colors (black and white) to represent pixels in the image. Image of bitmap mode is also called black and white images. Because of its depth of 1, it is also known as one image. Since the bitmap mode uses black and white to represent the pixel of the image, a large number of details are lost when converting the image into bitmap mode, so Photoshop provides several algorithms to simulate the detail of the lost images. In the case where the width, height, and resolution, the image size of the bitmap mode is minimum, about 1/7 and RGB mode of the grayscale mode, and 1/22 or less. 2. Grayscale mode grayscale mode can use up to 256 gradation to express an image, so that the transition of the image is smoother and delicate. Each pixel of the grayscale image has a luminance value between 0 (black) to 255 (white). The grayscale value can also be expressed in a percentage of black ink coverage (0% equal to white, 100% equal to black). The image generated using a black fold or grayscale scanner is often displayed in grayscale. 3. Duotone mode double-color mode uses 2-4 color inks to create a two-tone (2 colors), three colors (three colors) and four color tuning (4 colors) mixed their colors image. During the conversion of grayscale images into two-tone mode, the tones can be edited, and special effects are generated. The most important use of two-tone mode is to use as little color performance as color level, which is important for reducing printing costs, because when printing, each additional hue requires a greater cost.
4. Indexed Color Mode Index Color Mode is an image mode that is commonly used online and animation, and contains nearly 256 colors after the color image is converted to an index color. The index color image contains a color table. If the color in the original image cannot be used in 256 color performance, Photoshop selects the most similar color from the colors that can be used, so that the size of the image file can be reduced. The color index used to store the image and establish a color index for these colors, and the color table can define during the conversion or modify after the index image is claimed. 5. MultiChannel mode Multi-channel mode is very useful for images with special print requirements. For example, if only one or two or two colors are used in the image, the printing cost can be reduced and the correct output of the image color can be reduced using multiple channel modes. 6. 8-bit / 16-bit channel mode In the grayscale RGB or CMYK mode, a 16-bit channel can be used instead of the default 8-bit channel. According to the default, the 8-bit channel contains 256 colors, and if it is increased to 16 bits, the color order of each channel is 65,5536, so that more color details can be obtained. Photoshop identifies and inputs an image of 16-bit channels, but for this image limit, all filters cannot be used, and the image of the other 16-bit channel mode cannot be printed. Six, the conversion of color mode In order to correctly output images in different occasions, it is sometimes necessary to convert images from one mode to another. PHOTOSHOP converts the required color mode by performing the command in the Image / Mode submenu. This conversion of this color mode sometimes permanently changes the color value in the image. For example, when the RGB mode image is converted into a CMYK mode image, the RGB color value other than the CMYK color gamut is adjusted to the CMYK color gamut, thereby narrowing the color range. Since some colors lose part color information after conversion, it is best to save a backup file before the conversion is to recover images when necessary. 1. Converting the color image into the grayscale mode When converting the color image into a grayscale mode, Photoshop thrown away all the color information in the original image, and only retain the gray level of the pixel. The grayscale pattern can be used as intermediary modes that mutually transition between bitmap modes and color modes. 2. Conversion of other modes to bitmap mode to convert images into bitmap mode, reduce image color to two, which greatly simplifies color information in the image and reduces the size of the file. To convert the image into bitmap mode, you must first convert it to a grayscale mode. This will remove the color phase and saturation information of the pixel, but only keep the brightness value. However, since only few edit options can be used for bitmap mode images, it is best to edit images in the grayscale mode before converting it. After the bitmap mode image edited in the grayscale mode, it may be different. For example, in the bitmap mode, the pixel is black, and it may be gray after editing in the grayscale mode. If the pixels are bright enough, when converting backlink mode, it will become white. 3. Converting other modes to index mode When converting color images into an index color, you will delete a lot of colors in the image, but only the 256 colors of which are all in which many multimedia animation applications and web pages are supported. . Only images of grayscale mode and RGB mode can be converted to index color mode. Since the grayscale mode itself is composed of 256 gradation, there is no significant difference in color or image size after converting to index colors. However, after converting the image of the RGB mode into an index color mode, the size of the image will be significantly reduced, and the visual quality of the image will also be damaged. 4. Convert the image of the RGB mode into a CMYK mode If the image of the RGB mode is converted into a CMYK mode, the color in the image generates color, the color gamut of the color will be limited.
