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Resampling

Resampling. MALTAB. improfile(f,[XFP x],[YFP y],search_radius,' bicubic '); f ：原圖 [ ] ：座標 search_radius ：點數 bicubic ：函式. 各方法簡介 - 雙線性內插法. 雙線性內插法 (bilinear interpolation) 實際上為連續記算三次線性內插的結果 與最近相鄰內插法一樣，利用相鄰四點求取新的像素值 下頁式子中的 α 、 β 為點 p 對應鄰近四點的相對水平與垂直距離 假設點與點間距離為 1 ， 故 0 < α 、 β < 1. 3.

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Resampling

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  1. Resampling

  2. MALTAB • improfile(f,[XFP x],[YFP y],search_radius,'bicubic'); • f：原圖 • [ ] ：座標 • search_radius ：點數 • bicubic：函式

  3. 各方法簡介-雙線性內插法 • 雙線性內插法(bilinear interpolation) • 實際上為連續記算三次線性內插的結果 • 與最近相鄰內插法一樣，利用相鄰四點求取新的像素值 • 下頁式子中的α、β為點p對應鄰近四點的相對水平與垂直距離 • 假設點與點間距離為1 ， 故 0 < α、β < 1 3

  4. 各方法簡介-雙線性內插法 • 作法 • 第一次線性內插 • 即a 、b兩點對p的影響，可求出e點像素 • 第二次線性內插 • 即c 、d兩點對p的影響，可求出f點像素 • 最後對e 、f兩點做內插 可求得p點像素 4

  5. C / C++ • //計算bilinear需要的alpha,beta值 • alpha = point_x - prepoint_x ; • beta = 1 - ( point_y - prepoint_y ) ; • //start bilinear interpolation • gray_a = ( 1 - alpha ) * *( pImage + 8 * ( prepoint_x ) + ( prepoint_y + 1 ) ) + alpha * *( pImage + 8 * ( prepoint_x + 1 ) + ( prepoint_y + 1 ) ) ; • gray_b = ( 1 - alpha ) * *( pImage + 8 * ( prepoint_x ) + ( prepoint_y ) ) + alpha * *( pImage + 8 * ( prepoint_x + 1 ) + ( prepoint_y ) ) ; • last_gray = ( 1 - beta ) * gray_a + beta * gray_b ; • gray_value[ count1++ ] = ( int )last_gray ;

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