mlib_imagesubsampleaverage(3mlib) [opensolaris man page]

mlib_ImageSubsampleAverage(3MLIB)			    mediaLib Library Functions				 mlib_ImageSubsampleAverage(3MLIB)

NAME

       mlib_ImageSubsampleAverage, mlib_ImageSubsampleAverage_Fp - subsamples an image with a box filter

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_ImageSubsampleAverage(mlib_image *dst,
	    const mlib_image *src, mlib_d64 xscale, mlib_d64 yscale);

       mlib_status mlib_ImageSubsampleAverage_Fp(mlib_image *dst,
	    const mlib_image *src, mlib_d64 xscale, mlib_d64 yscale);

DESCRIPTION

       Each function scales an image down with an adaptive box filter.

       The subsampling algorithm performs the scaling operation by averaging all the pixel values from a block in the source image that correspond
       to the destination pixel.

       The width and height of the source block for a destination pixel are computed as:

	   blockX = (int)ceil(1.0/xscale);
	   blockY = (int)ceil(1.0/yscale);

       If we denote a pixel's location in an image by its column number and row number (both counted from 0), the destination pixel at (i,  j)	is
       backward mapped to the source block whose upper-left corner pixel is at (xValues[i], yValues[j]), where

	   xValues[i] = (int)(i/xscale + 0.5);
	   yValues[j] = (int)(j/yscale + 0.5);

       The width and height of the filled area in the destination are restricted by

	   dstW = (int)(srcWidth * xscale);
	   dstH = (int)(srcHeight * yscale);

       where srcWidth and srcHeight are width and height of the source image.

       Since  the block size in source is defined from scale factors with roundup, some blocks (the rightmost and the bottommost blocks) may over-
       run the border of the source image by 1 pixel. In this case, such blocks are moved by 1 pixel to left/up direction in order to be inside of
       the source image.

PARAMETERS

       The function takes the following arguments:

       dst	 Pointer to destination image.

       src	 Pointer to source image.

       xscale	 X scale factor. 0.0 < xscale <= 1.0.

       yscale	 Y scale factor. 0.0 < yscale <= 1.0.

RETURN VALUES

       The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_ImageSubsampleBinaryToGray(3MLIB),	   mlib_ImageFilteredSubsample(3MLIB),	   mlib_ImageZoomTranslate(3MLIB),    mlib_ImageZoomTrans-
       late_Fp(3MLIB), attributes(5)

SunOS 5.11							    2 Mar 2007					 mlib_ImageSubsampleAverage(3MLIB)

Check Out this Related Man Page

mlib_ImageThresh2_Fp(3MLIB)				    mediaLib Library Functions				       mlib_ImageThresh2_Fp(3MLIB)

NAME

       mlib_ImageThresh2_Fp - image thresholding

SYNOPSIS

       cc [ flag... ] file... -lmlib [ library... ]
       #include <mlib.h>

       mlib_status mlib_ImageThresh2_Fp(mlib_image *dst, const mlib_image *src,
	    const mlib_d64 *thresh, const mlib_d64 *glow);

DESCRIPTION

       The  mlib_ImageThresh2_Fp() function compares each pixel in the floating-point source image to a threshold value. If the pixel is less than
       or equal to the threshold value, then the destination pixel is set to the low output level. If the pixel  is  greater  than  the  threshold
       value, then the destination pixel is set to the value of the source pixel.

       It uses the following equation:

	 dst[x][y][i] = glow[i]       if src[x][y][i] <= thresh[i]
	 dst[x][y][i] = src[x][y][i]  if src[x][y][i] > thresh[i]

PARAMETERS

       The function takes the following arguments:

       dst	 Pointer to destination image.

       src	 Pointer to source image.

       thresh	 Threshold value. thresh[i] contains the threshold for channel i.

       glow	 Low output level. glow[i] contains the low output level for channel i.

RETURN VALUES

       The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.

ATTRIBUTES

       See attributes(5) for descriptions of the following attributes:

       +-----------------------------+-----------------------------+
       |      ATTRIBUTE TYPE	     |	    ATTRIBUTE VALUE	   |
       +-----------------------------+-----------------------------+
       |Interface Stability	     |Committed 		   |
       +-----------------------------+-----------------------------+
       |MT-Level		     |MT-Safe			   |
       +-----------------------------+-----------------------------+

SEE ALSO

       mlib_ImageThresh1(3MLIB),   mlib_ImageThresh1_Fp(3MLIB),   mlib_ImageThresh1_Fp_Inp(3MLIB),   mlib_ImageThresh1_Inp(3MLIB),   mlib_ImageTh-
       resh2(3MLIB),   mlib_ImageThresh2_Fp_Inp(3MLIB),   mlib_ImageThresh2_Inp(3MLIB),   mlib_ImageThresh3(3MLIB),   mlib_ImageThresh3_Fp(3MLIB),
       mlib_ImageThresh3_Fp_Inp(3MLIB),   mlib_ImageThresh3_Inp(3MLIB),   mlib_ImageThresh4(3MLIB),   mlib_ImageThresh4_Fp(3MLIB),   mlib_ImageTh-
       resh4_Fp_Inp(3MLIB), mlib_ImageThresh4_Inp(3MLIB), mlib_ImageThresh5(3MLIB), mlib_ImageThresh5_Fp(3MLIB),  mlib_ImageThresh5_Fp_Inp(3MLIB),
       mlib_ImageThresh5_Inp(3MLIB), attributes(5)

SunOS 5.11							    2 Mar 2007					       mlib_ImageThresh2_Fp(3MLIB)

Linux and UNIX Man Pages

mlib_imagesubsampleaverage(3mlib) [opensolaris man page]

Check Out this Related Man Page