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79 lines
2.1 KiB
C
79 lines
2.1 KiB
C
/*
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* The Python Imaging Library
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* $Id$
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*
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* mode filter
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*
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* history:
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* 2002-06-08 fl Created (based on code from IFUNC95)
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* 2004-10-05 fl Rewritten; use a simpler brute-force algorithm
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*
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* Copyright (c) Secret Labs AB 2002-2004. All rights reserved.
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*
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* See the README file for information on usage and redistribution.
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*/
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#include "Imaging.h"
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Imaging
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ImagingModeFilter(Imaging im, int size)
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{
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Imaging imOut;
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int x, y, i;
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int xx, yy;
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int maxcount;
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UINT8 maxpixel;
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int histogram[256];
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if (!im || im->bands != 1 || im->type != IMAGING_TYPE_UINT8)
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return (Imaging) ImagingError_ModeError();
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imOut = ImagingNewDirty(im->mode, im->xsize, im->ysize);
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if (!imOut)
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return NULL;
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size = size / 2;
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for (y = 0; y < imOut->ysize; y++) {
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UINT8* out = &IMAGING_PIXEL_L(imOut, 0, y);
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for (x = 0; x < imOut->xsize; x++) {
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/* calculate histogram over current area */
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/* FIXME: brute force! to improve, update the histogram
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incrementally. may also add a "frequent list", like in
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the old implementation, but I'm not sure that's worth
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the added complexity... */
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memset(histogram, 0, sizeof(histogram));
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for (yy = y - size; yy <= y + size; yy++)
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if (yy >= 0 && yy < imOut->ysize) {
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UINT8* in = &IMAGING_PIXEL_L(im, 0, yy);
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for (xx = x - size; xx <= x + size; xx++)
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if (xx >= 0 && xx < imOut->xsize)
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histogram[in[xx]]++;
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}
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/* find most frequent pixel value in this region */
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maxpixel = 0;
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maxcount = histogram[maxpixel];
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for (i = 1; i < 256; i++)
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if (histogram[i] > maxcount) {
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maxcount = histogram[i];
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maxpixel = (UINT8) i;
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}
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if (maxcount > 2)
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out[x] = maxpixel;
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else
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out[x] = IMAGING_PIXEL_L(im, x, y);
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}
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}
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ImagingCopyPalette(imOut, im);
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return imOut;
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}
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