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https://github.com/python-pillow/Pillow.git
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114 lines
2.9 KiB
C
114 lines
2.9 KiB
C
/*
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* The Python Imaging Library
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* $Id$
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*
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* min, max, median filters
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*
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* history:
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* 2002-06-08 fl Created
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*
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* Copyright (c) Secret Labs AB 2002. 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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/* Fast rank algorithm (due to Wirth), based on public domain code
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by Nicolas Devillard, available at http://ndevilla.free.fr */
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#define SWAP(type,a,b) { register type t=(a);(a)=(b);(b)=t; }
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#define MakeRankFunction(type)\
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static type Rank##type(type a[], int n, int k)\
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{\
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register int i, j, l, m;\
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register type x;\
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l = 0; m = n-1;\
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while (l < m) {\
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x = a[k];\
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i = l;\
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j = m;\
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do {\
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while (a[i] < x) i++;\
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while (x < a[j]) j--;\
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if (i <= j) {\
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SWAP(type, a[i], a[j]);\
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i++; j--;\
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}\
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} while (i <= j);\
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if (j < k) l = i;\
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if (k < i) m = j;\
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}\
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return a[k];\
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}
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MakeRankFunction(UINT8)
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MakeRankFunction(INT32)
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MakeRankFunction(FLOAT32)
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Imaging
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ImagingRankFilter(Imaging im, int size, int rank)
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{
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Imaging imOut = NULL;
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int x, y;
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int i, margin, size2;
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if (!im || im->bands != 1 || im->type == IMAGING_TYPE_SPECIAL)
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return (Imaging) ImagingError_ModeError();
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if (!(size & 1))
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return (Imaging) ImagingError_ValueError("bad filter size");
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/* malloc check ok, for overflow in the define below */
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if (size > INT_MAX / size ||
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size > INT_MAX / (size * sizeof(FLOAT32))) {
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return (Imaging) ImagingError_ValueError("filter size too large");
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}
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size2 = size * size;
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margin = (size-1) / 2;
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if (rank < 0 || rank >= size2)
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return (Imaging) ImagingError_ValueError("bad rank value");
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imOut = ImagingNew(im->mode, im->xsize - 2*margin, im->ysize - 2*margin);
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if (!imOut)
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return NULL;
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/* malloc check ok, checked above */
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#define RANK_BODY(type) do {\
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type* buf = malloc(size2 * sizeof(type));\
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if (!buf)\
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goto nomemory;\
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for (y = 0; y < imOut->ysize; y++)\
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for (x = 0; x < imOut->xsize; x++) {\
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for (i = 0; i < size; i++)\
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memcpy(buf + i*size, &IMAGING_PIXEL_##type(im, x, y+i),\
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size * sizeof(type));\
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IMAGING_PIXEL_##type(imOut, x, y) = Rank##type(buf, size2, rank);\
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}\
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free(buf); \
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} while (0)
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if (im->image8)
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RANK_BODY(UINT8);
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else if (im->type == IMAGING_TYPE_INT32)
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RANK_BODY(INT32);
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else if (im->type == IMAGING_TYPE_FLOAT32)
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RANK_BODY(FLOAT32);
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else {
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/* safety net (we shouldn't end up here) */
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ImagingDelete(imOut);
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return (Imaging) ImagingError_ModeError();
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}
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ImagingCopyPalette(imOut, im);
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return imOut;
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nomemory:
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ImagingDelete(imOut);
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return (Imaging) ImagingError_MemoryError();
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}
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