Several common problems in GDI + (8)

Haha, this week, the eighth episode of Heroes finally came out, I continue to go down the last section of the story, modify the color how to do.

8.1 Using the original method to modify the RGB and hue, saturation and brightness of the image

The simplest way, very easy, is to use the previous lockbits, and then directly modify the value of the r,g,b, the specific is not much to say. In GDI +, color has 3 methods, namely GetHue (), Getsaturation (), getbrightness (). It is the hue, saturation and brightness of the image. Where the hue value is [0,360], which indicates the current color at which angle, saturation and brightness are from [0,1], indicating the saturation and brightness of the color. Here, GDI + 's comments make another mistake, such as Getsaturation (): Gets the hue-saturation-brightness (HSB) saturation value for this Color structure. , saying that he is HSB, but in fact its value is the result of HSL. The person who wrote the note should pull out for a beating and not know how much time I wasted on it.

HSB also known as HSV, is also a very common color space, which is based on the separation of brightness information and color information, widely used in various computer image software. Another color space called HSL, similar to the HSV, but in the brightness and saturation of the treatment slightly different, interested students can go to check this article Http://en.wikipedia.org/wiki/HSL_color_space, There are a lot of beautiful pictures and detailed comparisons, I do not say more here. Here's a look at the HSV color space model:

To get to the point, if I want to modify the saturation of an image, how do I do it? GDI + did a half-baked thing, color inside there is a static method called FromArgb, but there is no way to call FROMHSL (float hue, float saturation, float lightness). So everyone is unhappy. Here I change the brightness to lightness to avoid errors in the annotation.

1 Private Color FROMHSL (float hue, float saturation, float lightness)
2 {
3　Double q = lightness < 0.5d? Lightness * (1 + saturation): Lightness + Saturation-(lightness * saturation);
4 Double p = 2 * LIGHTNESS-Q;
5 Double HK = hue/360d;　　　　　　　　　　　　　
6
7 double[] t = new double[3];//save RGB in array
8 t[0] = HK + 1/3d;
9 T[1] = HK;
Ten t[2] = hk-1/3d;
One
for (int i = 0; i < 3; i++)
{
if (T[i] < 0) T [i] + 1d;
if (T[i] > 1) t[i] = 1d;
0}

double[] color = new DOUBLE[3];
for (int i =;　;　3;　　　　　　　　　　　　　　　 　　　　　　i++)
{
if (T[i] < 1/6d)
{
23 Color[i] = p + ((q-p) * 6 * t[i]);　　　　　　　　
24 　　　　　　　　　
/Else if (T[i] < 1/2d)
{
color[ I] = q;　　　　　　　　　　　　　　　　　　　　　
}
Else if (T[i] < 2/3d)
{
31 Color[i] = p + ((q-p) * 6 * (2/3d-t[i)));
32}
-Else
36}< {
Color[i] = p;
　br>

Color.FromArgb (0,
(int) math.round (color[0) * 255d),
(int) math.round (color[1] * 255d),
(int) math.round (color[2] * 255d ));
[
}