图像处理之调整亮度与饱和度
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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