RM0020 datasheet(39/69 Pages) STMICROELECTRONICS

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RM0020

Function API

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#endif

ALIGN_DCC(4)

unsigned char a[16*12];

/* #pragma and ALIGN macros used to align to 4 bytes */

#ifdef __ghs__

#pragma alignvar (4)

#endif

ALIGN_DCC(4)

unsigned char b[16*12] ALIGN_MWERKS(4);

unsigned short M, N, shift;

void main(void)

{

/******** Sobel filter *********/

M = 16;

N = 12;

sobel3x3(a, b, M, N);

}

6.19

sobel3x3_horizontal - horizontal sobel filter

Function call:

void sobel3x3_horizontal(unsigned char *a, unsigned char *b,

unsigned short M, unsigned short N);

Arguments:

Description:

Computes the horizontal sobel filter on MxN input image. The absolute value of

horizontal sobel filter result is range limited to 0..255. The output image is of the same

size as input image and has one pixel border that is not computed. The first and the

last row of output image is not changed, the first column is zeroed and the last column

will contain not meaningful results. The last column can be zeroed when

ZERO_LASTCOL is defined to 1 for the penalty of one more instruction inside the

inner loop. The ZERO_LASTCOL is a symbol defined in function source file.

Table 19.

sobel3x3_horizontal arguments

a(1)

a and b must be word aligned.

input image of size MxN

b(1)

out

output image of size MxN

number of rows of a and b, must be >= 3

number of columns of a and b, must be multiple of 4, must be >= 8

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