第5章 數(shù)字圖像處理及其在交通中的應(yīng)用

第5章

數(shù)字圖像處理技術(shù)數(shù)字圖像基礎(chǔ)概念主要圖像處理技術(shù)圖像處理及其實例一、數(shù)字圖像基礎(chǔ)概念1.什么是數(shù)字圖像？離散化的圖像，亮度和坐標(biāo)均為有限、離散的數(shù)值?；叶葓D像（單色圖像）：每個像素的亮度用一個數(shù)值來表示，通常數(shù)值范圍在0到255之間（一個字節(jié)），0表示黑、255表示白，而其它表示灰度。單色圖像(lena)單色圖像的局部放大圖125,153,158,157,127,70,103,120,129,144,144,150,150,147,150,160,165,160,164,165,167,175,175,166,133,60,133,154,158,100,116,120,97,74,54,74,118,146,148,150,145,157,164,157,158,162,165,171,155,115,88,49,155,163,95,112,123,101,137,108,81,71,63,81,137,142,146,152,159,161,159,154,138,81,78,84,114,95,167,69,85,59,65,43,85,34,69,78,104,101,117,132,134,149,160,165,158,143,114,99,57,45,51,57,54,46,38,44,38,36,44,36,25,48,115,113,114,124,135,152,168,169,156,75,43,39,41,38,42,41,58,30,44,35,28,69,144,147,57,60,93,106,119,124,131,144,175,177,63,30,30,124,139,65,31,39,

61,35,75,51,66,58,167,177,153,58,80,95,108,120,133,155,182,137,84,74,54,61,149,96,36,29,115,71,84,105,86,136,172,175,128,126,114,106,109,115,127,169,187,105,102,95,66,135,145,87,38,38,124,120,106,93,95,117,120,131,148,144,113,112,109,115,128,162,193,143,132,124,110,131,97,53,66,47,129,123,128,114,108,115,102,121,129,125,113,112,111,111,127,162,192,150,129,117,112,107,64,67,73,48,133,139,132,127,128,134,136,144,140,141,113,120,114,115,122,154,188,159,143,131,125,112,105,95,88,52,136,138,143,145,138,143,143,141,144,129,118,119,115,112,120,152,186,165,150,139,128,117,109,104,93,58,140,146,147,145,150,154,147,149,143,132,127,124,117,112,117,142,184,171,144,139,129,119,114,112,100,58,135,143,145,151,150,143,146,142,139,131,131,127,119,115,114,140,190,177,141,135,133,121,120,115,102,48,128,137,141,149,150,148,143,141,136,128,120,122,116,109,116,136,182,182,140,135,130,124,116,109,100,45,131,132,141,143,148,147,143,140,134,125,116,117,108,109,120,130,171,185,133,132,127,120,117,110,90,42,136,131,139,136,140,141,140,136,132,121,114,117,109,106,112,130,163,192,130,131,127,119,116,110,81,26,126,131,132,132,136,140,134,135,128,117,110,113,111,110,112,129,151,196,155,130,127,120,115,103,64,28,127,132,130,128,134,134,140,132,126,110,102,117,118,114,112,121,152,195,165,123,128,117,115,96,36,28,123,131,127,129,132,133,134,131,127,112,109,117,114,116,107,116,145,172,136,123,122,116,107,72,27,28,127,128,129,130,133,135,132,134,130,120,108,110,48,79,76,103,128,165,137,127,118,115,105,34,31,28,123,124,127,128,132,129,134,131,131,124,114,109,115,117,106,120,151,149,134,126,118,114,85,30,36,29,122,122,123,128,132,133,134,133,132,127,128,125,120,138,130,158,162,149,130,123,115,106,36,34,29,29,124,124,122,124,129,130,126,134,130,130,124,123,127,164,155,162,163,144,128,128,117,97,37,29,29,41,……………..局部放大圖在計算機中的實際存在形式——二維矩陣藍(lán)青品紅紅黑白綠黃彩色圖像：利用人眼感光的三原色原理，用紅、綠、藍(lán)(RGB)三元組的二維矩陣來表示。如(255,0,0)表示純粹的紅色，(255,255,255)表示白色。歸一化的RGB顏色立方圖彩色圖像(lena)及其局部放大圖(207,137,130)(220,179,163)(215,169,161)(210,179,172)(210,179,172)(207,154,146)(217,124,121)(226,144,133)(226,144,133)(224,137,124)(227,151,136)(227,151,136)(226,159,142)(227,151,136)(230,170,154)(231,178,163)(231,178,163)(231,178,163)(236,187,171)(236,187,171)(239,195,176)(239,195,176)(240,205,187)(239,195,176)(231,138,123)(217,124,121)(215,169,161)(216,179,170)(216,179,170)(207,137,120)(159,51,71)(189,89,101)(216,111,110)(217,124,121)(227,151,136)(227,151,136)(226,159,142)(226,159,142)(237,159,135)(237,159,135)(231,178,163)(236,187,171)(231,178,163)(236,187,171)(236,187,171)(236,187,171)(239,195,176)(239,195,176)(236,187,171)(227,133,118)(213,142,135)(216,179,170)(221,184,170)(190,89,89)(204,109,113)(204,115,118)(189,85,97)(159,60,78)(136,38,65)(160,56,75)(204,109,113)(227,151,136)(226,159,142)(237,159,135)(227,151,136)(230,170,154)(231,178,163)(230,170,154)(231,178,163)(231,178,163)(236,187,171)(239,195,176)(230,170,154)(204,109,113)(178,73,83)(216,179,170)(220,188,176)(190,77,84)(206,95,97)(217,113,113)(189,85,97)(226,144,133)(207,91,94)(170,56,72)(159,51,71)(150,47,67)(172,63,78)(226,144,133)(226,144,133)(227,151,136)(226,159,142)(230,170,154)(231,178,163)(230,170,154)(230,170,154)(226,144,133)(172,63,78)(155,75,101)(155,75,101)(204,109,113)………………………彩色圖像局部放大圖在計算機中的實際存在形式（給出前四行）光源實際物體相機CCD平面上的像輸出的數(shù)字化圖像2.數(shù)字圖像獲取過程光學(xué)成像CCD光電轉(zhuǎn)換A/D轉(zhuǎn)換輸出圖像

連續(xù)圖像數(shù)字圖像像素像素：組成數(shù)字圖像的元素。每一個像素的坐標(biāo)對應(yīng)特定的圖像網(wǎng)格位置。像素的數(shù)值反映圖像中對應(yīng)位置的亮度。數(shù)字圖像的重要指標(biāo)。500萬像素——數(shù)碼相機主流像素，可以放大到24寸而看不出顆粒。3.空間和灰度級分辨率空間分辨率——圖像中可辨別的最小細(xì)節(jié)。主要由取樣值決定。

M×N像素灰度分辨率——在灰度級別中可分辨的最小變化。由量化級數(shù)決定。一般取灰度分辨率為8比特——灰度為256級不同空間分辨率圖像（灰度級為8比特）1024×1024；(b)~(f)的原始空間分辨率依次為512×512，256×256，128×128，64×64，32×32像素。(a)453×374，256灰度級圖像；(b)~(d)保持空間分辨率不變，以灰度級為128，64和32顯示的圖像（續(xù)）(e)~(h)以16，8，4和2灰度級顯示的圖像4.常用圖像格式BMP、JPEG、TIFF、GIF……特點：以像素為單位的矩形區(qū)域。（位圖）顏色深度：1,2,4,8,16,24bits/pixel編碼方式：無壓縮、無損壓縮、有損壓縮壓縮方式：LZW、RLE、JPEG、CCITT3、 CCITT4、JPEG2000BMP文件格式大部分BMP文件是不壓縮的形式，但支持圖像壓縮，如RLE格式和LZW壓縮格式等。Windows操作系統(tǒng)的標(biāo)準(zhǔn)文件格式BMP文件結(jié)構(gòu)GIF文件格式JPEG文件格式TIFF文件格式5.運算與操作——基于像素的圖像處理算術(shù)運算：加：對應(yīng)像素值累加；常用于對同一場景的多幅圖像求平均值，以降低加性隨機噪聲的影響。減（差分）：對應(yīng)像素值相減；用于檢測同一場景的兩幅圖像之間的變化（如運動檢測）乘：矯正數(shù)字化的敏感度影響；選擇感興趣區(qū)域除：矯正設(shè)備非線性影響；得到比率圖像邏輯運算：與(AND)、或(OR)、非(NOT)(c)RGB差值圖片(a)原始彩色圖片(b)提取的道路背景圖片

(d)二值化后的差值圖片

二、主要圖像處理技術(shù)圖像獲取與顯示圖像壓縮、存儲和傳輸圖像增強、恢復(fù)和重建圖像分割圖像表示和描述圖像特征的提取與圖像識別輸入圖像輸出圖像圖像數(shù)字化設(shè)備圖像處理計算機圖像輸出設(shè)備1.數(shù)字圖像處理過程2.圖像壓縮、存儲和傳輸圖像壓縮：減少描述圖像的數(shù)據(jù)量，節(jié)省圖像傳輸、處理時間，減少存儲空間。壓縮標(biāo)準(zhǔn)：圖像壓縮標(biāo)準(zhǔn)：RLE、LZW、JPEG……視頻壓縮標(biāo)準(zhǔn)：H.261、MPEG-1、MPEG-2、MPEG-4存儲格式：圖像存儲格式：BMP、JPG、TIF、GIF……視頻存儲格式：AVI、RM、MPEG、VOB、ASF…….圖像傳輸：有線：網(wǎng)絡(luò)、電纜……無線：3G、CDMA、GPRS……3.圖像增強、恢復(fù)和重建提高圖像質(zhì)量，如去除噪聲、提高圖像的清晰度等。采用的方法：灰度調(diào)節(jié)平均算術(shù)、邏輯運算……(a)NASA表面探測器拍攝的火星衛(wèi)星圖像；(b)圖(a)的直方圖(c)經(jīng)過直方圖拉伸增強處理后的圖像，陰影處細(xì)節(jié)可見；(d)圖(c)的直方圖(a)