Picture color space Problem _ related skills

1.RGB Model: The color is represented by a combination of red, green, and blue that is related to brightness, and the RGB model is based on the addition of color;

2.Lab color mode: Lab Color mode can be said to be the largest range of color mode, is a device-independent color space. The lab color model represents color in three sets of values.
L:lightness brightness value, from 0 to 100.
A: The area between red and green between the two primary colors, with values ranging from 120 to +120.
B: Yellow to blue between the two primary colors of the change area, the value from 120 to +120

3.YIQ color space: YIQ color space is often used by North American television systems and belongs to the NTSC (National Television Standards Committee) system.

4.YUV color space: YUV color space and yiq color space, are used in television systems, but not the same YUV color space by the European television system, belongs to the PAL (Phase alternation line) system.

5.YCrCb color space: is a common color space. The color space used by JPEG images everywhere on the web is exactly that space. It is derived from YUV color space. Which, y is still brightness, and CR and CB is to do a small amount of adjustment of U and V, the CR represents Red component, CB represents blue component.

6.HSI color space: HSI color space is from the human visual system, with Hue (Hue), color saturation (saturation or chroma) and brightness (intensity or brightness) to describe the color.

7.HSV (hue hue, saturation saturation, brightness value), also known as HSB (b refers to brightness), is commonly used by artists, because it is more natural and intuitive to use concepts such as hue, saturation and so on to describe colors as compared with additive subtraction and blending.

8.HSL (hue hue, saturation saturation, lightness lightness/luminance), also known as HLS or HSI (I refers to intensity) is very similar to HSV, only "lightness" (lightness) instead of "brightness" (brightness).

9.cmy/cmyk Color System: Color printing or color printing of paper is not able to emit light, so the printing press or color printer can only use some to absorb specific light waves and reflect other light waves of ink or pigments.

I do not know how many friends encountered this kind of problem: in the PS processing a good picture, sent to the Forum on the later found that the picture color changes, become gray, lost levels, color blunt, and a little blue hair. If you have, then, you must read this post. Giyu, An Meng asked this question, I happen to jiehuaxianfo my friend Xi ' an photo of friends Zho Fung a post to everyone, hope to help.

First, let's talk about preliminary knowledge: about color space.

We know that the display is a red (R) Green (G) Blue (B) Three colors to simulate the changing nature of the color, and digital camera images are also RGB three-color information. If the camera and the monitor use the same number to represent the same color, then the image we see on the camera and the monitor should be the same color. However, the color of the software developed by different vendors is not the same, resulting in the same picture in different environments, the color has changed. The corresponding relationship between the color and the actual value is the first noun I want to say: color space. At present, the most famous is the sRGB and AdobeRGB two kinds of color space. sRGB appeared earlier, is to display imitation color and research; AdobeRGB is the adobe company for printing color problems. The two color spaces are not the same, so the problem arises.

In general, small DCs do not have this problem, because the default color space is sRGB. Only high-end DC and SLR digital for later photo color more real, the default color space set to AdobeRGB. In this way, if the film to do a simple color matching crop scaling, then the film still retains the AdobeRGB color space, when we send such a film to the forum, the problem comes.

We generally use IE and other browsers to the forum, and the browser does not know Adobe, he will use sRGB color corresponding relationship to display the picture, so, we see the picture of the color of the big change.

To avoid this, you must convert the color space of the picture before you map it.

Method 1, removal of information method: The method is transformed, the color of the picture in the corresponding relationship to remove, so that it automatically converted to the standard sRGB color space.
How to: Open the picture with any image processing tool, save the picture as BMP format, choose 24-bit color, and choose Windows in the format. Save and then open the picture for processing, at this time the picture has been converted to sRGB by default.
This method does not have any technique, can be called stupid method, apply to anyone, need not urgent what theory, parameter, as long as save again to open on the line. However, this method will lose information, not only color space, as well as EXIF information, and file size will be increased dozens of times times, not recommended.

Method 2, Color space Unification method: This method by modifies the camera color space to achieve the color unification. The color space of the camera is set to sRGB. The specific settings method several different, need to see the camera description.
This method is simple, do not have to do what conversion, but, because the sRGB is for the screen display and developed, so the photos taken out if printed or printed, the color may change Oh!

Method 3, Color space conversion method: The camera or ADOBERGB, to ensure the quality of future flushing; Before the law, the use of tools to convert color space from Adobe to sRGB, to ensure that the image color unchanged.