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图像处理------应用卷积一实现噪声消去
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均值濾波：
均值濾波，是圖像處理中最常用的手段，從頻率域觀點(diǎn)來看均值濾波是一種低通濾波器，高
頻信號將會去掉，因此可以幫助消除圖像尖銳噪聲，實(shí)現(xiàn)圖像平滑，模糊等功能。理想的均
值濾波是用每個(gè)像素和它周圍像素計(jì)算出來的平均值替換圖像中每個(gè)像素。采樣Kernel數(shù)
據(jù)通常是3X3的矩陣，如下表示：
從左到右從上到下計(jì)算圖像中的每個(gè)像素，最終得到處理后的圖像。均值濾波可以加上兩個(gè)
參數(shù)，即迭代次數(shù)，Kernel數(shù)據(jù)大小。一個(gè)相同的Kernel，但是多次迭代就會效果越來越好。
同樣，迭代次數(shù)相同，Kernel矩陣越大，均值濾波的效果就越明顯。
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中值濾波
中值濾波也是消除圖像噪聲最常見的手段之一，特別是消除椒鹽噪聲，中值濾波的效果要比
均值濾波更好。中值濾波是跟均值濾波唯一不同是，不是用均值來替換中心每個(gè)像素，而是
將周圍像素和中心像素排序以后，取中值，一個(gè)3X3大小的中值濾波如下：
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最大最小值濾波
最大最小值濾波是一種比較保守的圖像處理手段，與中值濾波類似，首先要排序周圍像素和
中心像素值，然后將中心像素值與最小和最大像素值比較，如果比最小值小，則替換中心像
素為最小值，如果中心像素比最大值大，則替換中心像素為最大值。一個(gè)Kernel矩陣為3X3的最大最小值濾波如下：
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?原圖如下：
分別實(shí)現(xiàn)中值和均值濾波以后效果如下：
代碼就不解釋了，原理已經(jīng)解釋得很清楚了，全部算法源代碼都是基于Java
特別說明一點(diǎn)的是，均值濾波對于高斯噪聲的效果比較好，中值濾波對于椒鹽噪聲的效果比較好
想必大家從上面效果比較中也可以看到一點(diǎn)端倪。因?yàn)槲疫x擇的噪聲圖片是椒鹽噪聲的，哈哈
自己讀吧，不解釋了，有問題的可以問，源代碼如下：
[java]?view plaincopy
package?com.process.blur.study;????import?java.awt.image.BufferedImage;??import?java.util.ArrayList;??import?java.util.Arrays;??????public?class?SmoothFilter?extends?AbstractBufferedImageOp?{??????public?final?static?int?MEAN_FILTER_TYPE?=?1;??????public?final?static?int?MEADIAN_FILTER_TYPE?=?2;??????public?final?static?int?MIN_MAX_FILTER_TYPE?=?4;????????????private?int?repeats?=?3;???????private?int?kernel_size?=?3;???????private?int?type?=?1;?????????????public?int?getRepeat()?{??????????return?repeats;??????}????????????public?void?setRepeat(int?repeat)?{??????????this.repeats?=?repeat;??????}????????????public?int?getKernelSize()?{??????????return?kernel_size;??????}????????????public?void?setKernelSize(int?kernelSize)?{??????????this.kernel_size?=?kernelSize;??????}????????????public?int?getType()?{??????????return?type;??????}????????????public?void?setType(int?type)?{??????????this.type?=?type;??????}????????@Override??????public?BufferedImage?filter(BufferedImage?src,?BufferedImage?dest)?{??????????int?width?=?src.getWidth();??????????int?height?=?src.getHeight();????????????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?);??????????????????????????????if(this.type?==?MEAN_FILTER_TYPE)???????????{??????????????for(int?i=0;?i<repeats;?i++)?{??????????????????performMeanFilter(width,?height,?inPixels,?outPixels);??????????????????System.arraycopy(outPixels,?0,?inPixels,?0,?inPixels.length);??????????????}??????????}???????????else?if(this.type?==?MEADIAN_FILTER_TYPE)???????????{??????????????performMedianFilter(width,?height,?inPixels,?outPixels);??????????}???????????else?if(this.type?==?MIN_MAX_FILTER_TYPE)???????????{??????????????performMinMaxFilter(width,?height,?inPixels,?outPixels);??????????}??????????????????????????????setRGB(?dest,?0,?0,?width,?height,?outPixels?);??????????return?dest;??????}?????????????????????????public?void?performMeanFilter(int?width,?int?height,?int[]?inPixels,?int[]?outPixels)?{????????????int?rows2?=?kernel_size/2;??????????int?cols2?=?kernel_size/2;??????????int?index?=?0;??????????int?index2?=?0;??????????float?total?=?kernel_size?*?kernel_size;??????????for?(int?y?=?0;?y?<?height;?y++)?{??????????????for?(int?x?=?0;?x?<?width;?x++)?{??????????????????float?r?=?0,?g?=?0,?b?=?0,?a?=?0;??????????????????for?(int?row?=?-rows2;?row?<=?rows2;?row++)?{??????????????????????int?rowoffset?=?y?+?row;??????????????????????if(rowoffset?<?0?||?rowoffset?>=height)?{??????????????????????????rowoffset?=?y;??????????????????????}????????????????????????????????????????????for(int?col?=?-cols2;?col?<=?cols2;?col++)?{??????????????????????????int?coloffset?=?col?+?x;??????????????????????????if(coloffset?<?0?||?coloffset?>=?width)?{??????????????????????????????coloffset?=?x;??????????????????????????}??????????????????????????index2?=?rowoffset?*?width?+?coloffset;??????????????????????????int?rgb?=?inPixels[index2];??????????????????????????a?+=?((rgb?>>?24)?&?0xff);??????????????????????????r?+=?((rgb?>>?16)?&?0xff);??????????????????????????g?+=?((rgb?>>?8)?&?0xff);??????????????????????????b?+=?(rgb?&?0xff);??????????????????????}??????????????????}??????????????????int?ia?=?0xff;??????????????????int?ir?=?clamp((int)(r/total));??????????????????int?ig?=?clamp((int)(g/total));??????????????????int?ib?=?clamp((int)(b/total));??????????????????outPixels[index++]?=?(ia?<<?24)?|?(ir?<<?16)?|?(ig?<<?8)?|?ib;??????????????}??????????}??????}????????????????????public?void?performMedianFilter(int?width,?int?height,?int[]?inPixels,?int[]?outPixels)?{????????????int?rows2?=?kernel_size/2;??????????int?cols2?=?kernel_size/2;??????????int?index?=?0;??????????int?index2?=?0;??????????float?total?=?kernel_size?*?kernel_size;??????????int[]?matrix?=?new?int[(int)total];??????????for?(int?y?=?0;?y?<?height;?y++)?{??????????????for?(int?x?=?0;?x?<?width;?x++)?{??????????????????int?count?=?0;??????????????????for?(int?row?=?-rows2;?row?<=?rows2;?row++)?{??????????????????????int?rowoffset?=?y?+?row;??????????????????????if(rowoffset?<?0?||?rowoffset?>=height)?{??????????????????????????rowoffset?=?y;??????????????????????}????????????????????????for(int?col?=?-cols2;?col?<=?cols2;?col++)?{??????????????????????????int?coloffset?=?col?+?x;??????????????????????????if(coloffset?<?0?||?coloffset?>=?width)?{??????????????????????????????coloffset?=?x;??????????????????????????}??????????????????????????index2?=?rowoffset?*?width?+?coloffset;??????????????????????????int?rgb?=?inPixels[index2];??????????????????????????matrix[count]?=?rgb;??????????????????????????count++;???????????????????????}??????????????????}??????????????????Arrays.sort(matrix);????????????????????????????????????int?ia?=?0xff;??????????????????int?ir?=?((matrix[count/2]?>>?16)?&?0xff);??????????????????int?ig?=?((matrix[count/2]?>>?8)?&?0xff);??????????????????int?ib?=?(matrix[count/2]?&?0xff);??????????????????outPixels[index++]?=?(ia?<<?24)?|?(ir?<<?16)?|?(ig?<<?8)?|?ib;??????????????}??????????}??????}??????????????????????????public?void?performMinMaxFilter(int?width,?int?height,?int[]?inPixels,?int[]?outPixels)?{??????????int?rows2?=?kernel_size/2;??????????int?cols2?=?kernel_size/2;??????????int?index?=?0;??????????int?index2?=?0;??????????float?total?=?kernel_size?*?kernel_size;??????????int[]?matrix?=?new?int[(int)total];??????????for?(int?y?=?0;?y?<?height;?y++)?{??????????????for?(int?x?=?0;?x?<?width;?x++)?{??????????????????int?count?=?0;??????????????????for?(int?row?=?-rows2;?row?<=?rows2;?row++)?{??????????????????????int?rowoffset?=?y?+?row;??????????????????????if(rowoffset?<?0?||?rowoffset?>=height)?{??????????????????????????rowoffset?=?y;??????????????????????}????????????????????????for(int?col?=?-cols2;?col?<=?cols2;?col++)?{??????????????????????????int?coloffset?=?col?+?x;??????????????????????????if(coloffset?<?0?||?coloffset?>=?width)?{??????????????????????????????coloffset?=?x;??????????????????????????}??????????????????????????index2?=?rowoffset?*?width?+?coloffset;??????????????????????????int?rgb?=?inPixels[index2];??????????????????????????matrix[count]?=?rgb;??????????????????????????count++;???????????????????????}??????????????????}??????????????????int?ia?=?0xff;??????????????????int?oldPixel?=?matrix[count/2];??????????????????int?targetRGB?=?findNewPixel(matrix,?oldPixel);??????????????????int?ir?=?((targetRGB?>>?16)?&?0xff);??????????????????int?ig?=?((targetRGB?>>?8)?&?0xff);??????????????????int?ib?=?(targetRGB?&?0xff);??????????????????outPixels[index++]?=?(ia?<<?24)?|?(ir?<<?16)?|?(ig?<<?8)?|?ib;??????????????}??????????}??????}????????????private?int?findNewPixel(int[]?matrix,?int?oldPixel)?{??????????ArrayList<Integer>?list?=?new?ArrayList<Integer>();??????????for(int?i=0;?i<matrix.length;?i++)?{??????????????if(matrix[i]?==?oldPixel)??????????????????continue;??????????????list.add(matrix[i]);??????????}??????????int[]?filterData?=?new?int[list.size()];??????????int?index?=?0;??????????for(Integer?rgb?:?list)?{??????????????filterData[index++]?=?rgb;??????????}??????????Arrays.sort(filterData);????????????????????if(filterData.length?==?0)??????????????return?oldPixel;??????????return?(oldPixel?>?filterData[0])???filterData[0]?:?(oldPixel?<?filterData[filterData.length?-1])??filterData[filterData.length?-1]?:?oldPixel;??????}????????public?static?int?clamp(int?c)?{??????????if?(c?<?0)??????????????return?0;??????????if?(c?>?255)??????????????return?255;??????????return?c;??????}????}??
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