遙感數(shù)字圖像增強PPT學習教案

1、會計學1輸入圖像顯示直方圖確定分割的等級數(shù)，并計算分割的間距像元亮度值轉(zhuǎn)換為為像元像元新值新值賦色賦色HOME第1頁/共65頁第2頁/共65頁第3頁/共65頁第4頁/共65頁第5頁/共65頁TM1TM2TM3TM4TM5TM6TM7第6頁/共65頁TM7,4,1TM5,7,2TM5,4,3TM4,3,2第7頁/共65頁第8頁/共65頁第9頁/共65頁第10頁/共65頁第11頁/共65頁A linear stretch involves identifying lower and upper bounds from the histogram (usually the minimum and m

2、aximum brightness values in the image) and applying a transformation to stretch this range to fill the full range. 第12頁/共65頁This graphic illustrates the increase in contrast in an image before (left) and after (right) a linear contrast stretch. 第13頁/共65頁If the input range is not uniformly distribute

3、d. In this case, a histogram-equalised stretch may be better. This stretch assigns more display values (range) to the frequently occurring portions of the histogram. In this way, the detail in these areas will be better enhanced relative to those areas of the original histogram where values occur le

4、ss frequently第14頁/共65頁This graphic illustrates the rather uneven increase in contrast in an image before (left) and after (right) a histogram equalised stretch. 第15頁/共65頁第16頁/共65頁第17頁/共65頁A common filtering involves moving a window （活動窗口）of a few pixels in dimension (e.g. 3x3, 5x5, etc.) over each p

5、ixel in the image, applying a mathematical calculation using the pixel values under that window, and replacing the central pixel with the new value. 第18頁/共65頁Image of CHURN FarmDaedalus 1268 ATM Channel 3第19頁/共65頁A low-pass filter（低通濾波）（低通濾波） is designed to emphasise larger, homogeneous areas of sim

6、ilar tone and reduce the smaller detail in an image. Thus, low-pass filters generally serve to smooth（平滑）（平滑） the appearance of an image. 第20頁/共65頁A high-pass filter （高通濾波）does the opposite, and serves to sharpen the appearance of fine detail in an image. 第21頁/共65頁Directional or edge detecting filte

7、rs highlight linear features, such as roads or field boundaries. Vertical edges（垂直邊緣）第22頁/共65頁Horizontal edgesDirectional Edge filters can also be designed to enhance features which are oriented in specific directions and are useful in applications such as geology, for the detection of linear geolog

8、ic structures. 第23頁/共65頁第24頁/共65頁第25頁/共65頁 第26頁/共65頁 第27頁/共65頁第28頁/共65頁第29頁/共65頁第30頁/共65頁第31頁/共65頁第32頁/共65頁第33頁/共65頁第34頁/共65頁第35頁/共65頁第36頁/共65頁第37頁/共65頁第38頁/共65頁第39頁/共65頁第40頁/共65頁第41頁/共65頁第42頁/共65頁圖像圖像預(yù)處預(yù)處理理圖 像 配圖 像 配準準圖 像 融圖 像 融合合識別識別后處理后處理決策基決策基礎(chǔ)礎(chǔ)預(yù)處理包括兩部分：圖像幾何校正與圖像配準第43頁/共65頁第44頁/共65頁第45頁/共65頁基于像元

9、的加權(quán)融合對兩幅圖像基于像元的加權(quán)融合對兩幅圖像 按下式進行：按下式進行：ijII，1(1 |),12iijijPrPP /ijijijr A，B為常數(shù)；為常數(shù)； 為兩個圖像的權(quán)，為兩個圖像的權(quán)，ijPP，為兩幅圖像的相關(guān)系數(shù)：為兩幅圖像的相關(guān)系數(shù)：()ijiijjIA PIP IB第46頁/共65頁1122 1/211()()() () mnKLKLjjKLjmnKLKLjjKLPPXSXSrPPXSXS1(1 |)(1 |)2KLjjKLjKLjGrPrXS 第47頁/共65頁第48頁/共65頁第49頁/共65頁第50頁/共65頁第51頁/共65頁1321,nnXXXXXX1, 3 , 2 , 1,2nnjimXmXEjjiiji第52頁/共65頁1, 12, 11 , 11, 22, 21 , 2112111nnn