图像处理------调整亮度与饱和度 分类： 视频图像处理 2015-07-24 14:50 31人阅读 评论(0) 收藏

什么是亮度：

简单点说一幅图像的亮度属性是图像的RGB值的大小，RGB各个值越大亮度越高RGB

分量取值范围为0～255之间。调整图像亮度。

什么是饱和度：

饱和度是是指颜色的强度，调整饱和度可以修正过度曝光或者未充分曝光的图片。使

图像看上去更加自然。

基本思想：

通常在RGB色彩空间调整亮度与饱和度不是很直观，而HSL彩色空可以很直观表示出

每个像素的饱和度与亮度。所以首先读取图像的像素RGB值然后再转换到HSL空间得

到饱和度与亮度值，调整以后再从HSL空间转换到RGB空间的RGB值，对每个像素完

成这样的调整就完成图像的亮度与饱和度调整。关于RGB与HSL色彩空间的转换

看这里：http://en.wikipedia.org/wiki/HSL_color_space

程序效果：

滤镜源代码：

package com.gloomyfish.filter.study;

import java.awt.image.BufferedImage;
/**
 * http://en.wikipedia.org/wiki/HSL_color_space
 * @author gloomy fish
 * @date 2012-09-26
 *
 */
public class HSLFilter extends AbstractBufferedImageOp {
    public final static double c1o60  = 1.0 / 60.0;
    public final static double c1o255 = 1.0 / 255.0;
    private double hue;
    private double saturation;
    private double lightness;

    public HSLFilter() {
        System.out.println("Hue Filter");
    }

    public double getHue() {
        return hue;
    }

    public void setHue(double hue) {
        while (hue < 0.0) {
            this.hue += 360;
        }
        while (hue >= 360.0) {
            this.hue -= 360;
        }
    }

    public double getSaturation() {
        return saturation;
    }

    public void setSaturation(double saturation) {
        if((saturation >= -100.0) && (saturation <= 100.0)) {
            this.saturation = saturation;
        }
    }

    public double getLightness() {
        return lightness;
    }

    public void setLightness(double lightness) {
        if((lightness >= -100.0) && (lightness <= 100.0)) {
            this.lightness = lightness;
        }
    }

    @Override
    public BufferedImage filter(BufferedImage src, BufferedImage dest) {
        int width = src.getWidth();
        int height = src.getHeight();
        double sat = 127.0d * saturation / 100.0d;
        double lum = 127.0d * lightness / 100.0d;
        if ( dest == null )
            dest = createCompatibleDestImage( src, null );

        int[] inPixels = new int[width*height];
        int[] outPixels = new int[width*height];
        getRGB( src, 0, 0, width, height, inPixels );
        double min, max, dif, sum;
        double f1, f2;
        int index = 0;
        double h, s, l;
        double v1, v2, v3, h1;
        for(int row=0; row<height; row++) {
            int ta = 0, tr = 0, tg = 0, tb = 0;
            for(int col=0; col<width; col++) {
                index = row * width + col;
                ta = (inPixels[index] >> 24) & 0xff;
                tr = (inPixels[index] >> 16) & 0xff;
                tg = (inPixels[index] >> 8) & 0xff;
                tb = inPixels[index] & 0xff;

                // convert to HSL space
                min = tr;
                if (tg < min)
                    min = tg;
                if (tb < min)
                    min = tb;
                max = tr;
                f1 = 0.0;
                f2 = tg - tb;
                if (tg > max) {
                   max = tg;
                   f1 = 120.0;
                   f2 = tb - tr;
                }
                if (tb > max) {
                   max = tb;
                   f1 = 240.0;
                   f2 = tr - tg;
                }
                dif = max - min;
                sum = max + min;
                l = 0.5 * sum;
                if (dif == 0) {
                    h = 0.0;
                    s = 0.0;
                }
                else if(l < 127.5) {
                    s = 255.0 * dif / sum;
                }
                else {
                    s = 255.0 * dif / (510.0 - sum);
                }

                h = (f1 + 60.0 * f2 / dif);
                if (h < 0.0) {
                    h += 360.0;
                }
                if (h >= 360.0) {
                    h -= 360.0;
                }

                // Apply transformation.
                h = h + hue;
                if( h >= 360.0) {
                    h = h - 360.0;
                }
                s = s + sat;
                if( s < 0.0) {
                    s = 0.0;
                }
                if( s > 255.0) {
                    s = 255.0;
                }
                l = l + lum;
                if( l < 0.0) {
                    l = 0.0;
                }
                if( l > 255.0) {
                    l = 255.0;
                }

                // conversion back to RGB space here!!
                if (s == 0) {
                   tr = (int)l;
                   tg = (int)l;
                   tb = (int)l;
                } else {

                   if (l < 127.5) {
                      v2 = c1o255 * l * (255 + s);
                   } else {
                      v2 = l + s - c1o255 * s * l;
                   }

                   v1 = 2 * l - v2;
                   v3 = v2 - v1;
                   h1 = h + 120.0;
                   if (h1 >= 360.0)
                       h1 -= 360.0;

                   if (h1 < 60.0) {
                      tr = (int)(v1 + v3 * h1 * c1o60);
                   }
                   else if (h1 < 180.0) {
                      tr = (int)v2;
                   }
                   else if (h1 < 240.0) {
                      tr = (int)(v1 + v3 * (4 - h1 * c1o60));
                   }
                   else {
                      tr = (int)v1;
                   }

                   h1 = h;
                   if (h1 < 60.0) {
                      tg = (int)(v1 + v3 * h1 * c1o60);
                   }
                   else if (h1 < 180.0) {
                      tg = (int)v2;
                   }
                   else if (h1 < 240.0) {
                      tg = (int)(v1 + v3 * (4 - h1 * c1o60));
                   }
                   else {
                      tg = (int)v1;
                   }

                   h1 = h - 120.0;
                   if (h1 < 0.0) {
                       h1 += 360.0;
                   }
                   if (h1 < 60.0) {
                      tb = (int)(v1 + v3 * h1 * c1o60);
                   }
                   else if (h1 < 180.0) {
                      tb = (int)v2;
                   }
                   else if (h1 < 240.0) {
                      tb = (int)(v1 + v3 * (4 - h1 * c1o60));
                   }
                   else {
                      tb = (int)v1;
                   }
                }
                outPixels[index] = (ta << 24) | (tr << 16) | (tg << 8) | tb;
            }
        }

        setRGB( dest, 0, 0, width, height, outPixels );
        return dest;
    }

}

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