MATLAB VIDEO AND IMAGE PROCESSING BLOCKSET 3 Guide de l'utilisateur télécharger pdf (Page 116)

5 Geometri c Transformation

123

456

789

represents your input image. You want to translate this image 0.5 p ixel in

the p ositiv e horiz ontal direction using b ilinear interpolation. The Translate

block’s bilinear interpolation algorithm is illustrated by the following steps:

1 Zero pad the input matrix and translate it by 0.5 pixel to the right.

0 1 1 2 2 3 3 0 0

0 4 4 5 5 6 6 0 0

0 7 7 8 8 9 9 0 0

0.5 pixel

Original zero-padded matrix

Translated zero-padded matrix

2 Create the output matrix by replacing each input pixel value with the

weighted average of the translated values on e ither side. T he result is

the following matrix where the output matrix has one more column than

the input matrix:

05 15 25 15

245553

35 75 85 45

....

For more information, see in the Image Proces sing Toolbox documentation.

Bicubic Interpolation

For bicubic interpolation, the block uses the weighted average of four

translated pixel values for each output pixel value.

For example, suppose this matrix,

5-4

1 2 ... 111 112 113 114 115 116 117 118 119 120 121 ... 251 252

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MATLAB VIDEO AND IMAGE PROCESSING BLOCKSET 3 Guide de l'utilisateur Page 116