Several common problems in GDI + (8. Rumored 1)

8. Color correction

I've been wrestling with the color space lately, and the transparent opacity of the front is just a special color. What I'm going to talk about today is the real fix color. We use the digital camera has different models, the photographic CCD performance is not the same, coupled with the weather or the surrounding light reasons, we may be out of the image of the color bias. In addition, in order to do some special processing, you may need to modify the color of a particular area in the photo. such as facial expression can be a little better, or hair darker a bit and so on. This topic is very large and I will spend a couple of weeks on this because it involves a lot of basic knowledge of image processing. Today we do not write code, only to talk about the theory (who let this week, the United States election, heroes eighth unexpectedly did not, I had to write out).

Rumored 1. RGB color Space

In the previous analysis, it was believed that all people knew what r,g,b was. We describe the color, the most commonly used is the use of RGB color space. By describing the three different components of a color, we can record the color value of a pixel. We do not involve the concept of equipment color space, but a little need to remember, (0,0,0) does not mean that All black, (255,255,255) does not mean that all white, on different devices, the display of content is not exactly the same. The solution to this problem depends on the ICM (http://www.color.org/) I spoke of earlier. If you want to add transparency, that is the four-dimensional space, (a,r,g,b). Each component can be quantified to a different level, so it creates 8-bit color, 16-bit color, and so on, which distinguishes a variety of colors until the human eye is unaware of the level. So for a beginner, the opaque color is a cube, a point in a three-dimensional space. The following figure

It's a very nice picture, but unfortunately, it's just one of the simplest ways to describe color, and it can describe the color content as extremely limited and imprecise. To understand the problem thoroughly, I want to help you analyze what the principle of light is, the wavelength of the color, the absorption and reflection of the material to different wavelengths of light, or diffuse reflection. Here I will not say more, interested students to find Physics department optics teacher to ask, people have been studying this problem for a lifetime. More interested students can go to the physics Department of the professor to discuss the light of the wave-particle duality, and then study the human eye on the optical feeling, and then study the surface of different materials on the reaction to the lights, and then study ..., stop it, ~!. You will end up in this life, so simply understand the color is RGB. It workers can understand that this is a good point.

Here to show you an interesting diagram, that is a color space called sRGB can describe the color, gray area is the human eye can perceive the color, the inside of that triangle is sRGB color space can describe the color. One thing to note is that the RGB color space is just a means of describing colors. can also refer to the specific Wikipedia:http://en.wikipedia.org/wiki/rgb