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/*
* The Python Imaging Library
* $Id: Histo.c 2134 2004-10-06 08:55:20Z fredrik $
*
* histogram support
*
* history:
* 1995-06-15 fl Created.
* 1996-04-05 fl Fixed histogram for multiband images.
* 1997-02-23 fl Added mask support
* 1998-07-01 fl Added basic 32-bit float/integer support
*
* Copyright (c) 1997-2003 by Secret Labs AB.
* Copyright (c) 1995-2003 by Fredrik Lundh.
*
* See the README file for information on usage and redistribution.
*/
#include "Imaging.h"
/* HISTOGRAM */
/* --------------------------------------------------------------------
* Take a histogram of an image. Returns a histogram object containing
* 256 slots per band in the input image.
*/
void
ImagingHistogramDelete(ImagingHistogram h)
{
if (h->histogram)
free(h->histogram);
free(h);
}
ImagingHistogram
ImagingHistogramNew(Imaging im)
{
ImagingHistogram h;
/* Create histogram descriptor */
h = calloc(1, sizeof(struct ImagingHistogramInstance));
strcpy(h->mode, im->mode);
h->bands = im->bands;
h->histogram = calloc(im->pixelsize, 256 * sizeof(long));
return h;
}
ImagingHistogram
ImagingGetHistogram(Imaging im, Imaging imMask, void* minmax)
{
ImagingSectionCookie cookie;
int x, y, i;
ImagingHistogram h;
INT32 imin, imax;
FLOAT32 fmin, fmax, scale;
if (!im)
return ImagingError_ModeError();
if (imMask) {
/* Validate mask */
if (im->xsize != imMask->xsize || im->ysize != imMask->ysize)
return ImagingError_Mismatch();
if (strcmp(imMask->mode, "1") != 0 && strcmp(imMask->mode, "L") != 0)
return ImagingError_ValueError("bad transparency mask");
}
h = ImagingHistogramNew(im);
if (imMask) {
/* mask */
if (im->image8) {
ImagingSectionEnter(&cookie);
for (y = 0; y < im->ysize; y++)
for (x = 0; x < im->xsize; x++)
if (imMask->image8[y][x] != 0)
h->histogram[im->image8[y][x]]++;
ImagingSectionLeave(&cookie);
} else { /* yes, we need the braces. C isn't Python! */
if (im->type != IMAGING_TYPE_UINT8)
return ImagingError_ModeError();
ImagingSectionEnter(&cookie);
for (y = 0; y < im->ysize; y++) {
UINT8* in = (UINT8*) im->image32[y];
for (x = 0; x < im->xsize; x++)
if (imMask->image8[y][x] != 0) {
h->histogram[(*in++)]++;
h->histogram[(*in++)+256]++;
h->histogram[(*in++)+512]++;
h->histogram[(*in++)+768]++;
} else
in += 4;
}
ImagingSectionLeave(&cookie);
}
} else {
/* mask not given; process pixels in image */
if (im->image8) {
ImagingSectionEnter(&cookie);
for (y = 0; y < im->ysize; y++)
for (x = 0; x < im->xsize; x++)
h->histogram[im->image8[y][x]]++;
ImagingSectionLeave(&cookie);
} else {
switch (im->type) {
case IMAGING_TYPE_UINT8:
ImagingSectionEnter(&cookie);
for (y = 0; y < im->ysize; y++) {
UINT8* in = (UINT8*) im->image[y];
for (x = 0; x < im->xsize; x++) {
h->histogram[(*in++)]++;
h->histogram[(*in++)+256]++;
h->histogram[(*in++)+512]++;
h->histogram[(*in++)+768]++;
}
}
ImagingSectionLeave(&cookie);
break;
case IMAGING_TYPE_INT32:
if (!minmax)
return ImagingError_ValueError("min/max not given");
if (!im->xsize || !im->ysize)
break;
imin = ((INT32*) minmax)[0];
imax = ((INT32*) minmax)[1];
if (imin >= imax)
break;
ImagingSectionEnter(&cookie);
scale = 255.0F / (imax - imin);
for (y = 0; y < im->ysize; y++) {
INT32* in = im->image32[y];
for (x = 0; x < im->xsize; x++) {
i = (int) (((*in++)-imin)*scale);
if (i >= 0 && i < 256)
h->histogram[i]++;
}
}
ImagingSectionLeave(&cookie);
break;
case IMAGING_TYPE_FLOAT32:
if (!minmax)
return ImagingError_ValueError("min/max not given");
if (!im->xsize || !im->ysize)
break;
fmin = ((FLOAT32*) minmax)[0];
fmax = ((FLOAT32*) minmax)[1];
if (fmin >= fmax)
break;
ImagingSectionEnter(&cookie);
scale = 255.0F / (fmax - fmin);
for (y = 0; y < im->ysize; y++) {
FLOAT32* in = (FLOAT32*) im->image32[y];
for (x = 0; x < im->xsize; x++) {
i = (int) (((*in++)-fmin)*scale);
if (i >= 0 && i < 256)
h->histogram[i]++;
}
}
ImagingSectionLeave(&cookie);
break;
}
}
}
return h;
}
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