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/*====================================================================*
- Copyright (C) 2001 Leptonica. All rights reserved.
-
- Redistribution and use in source and binary forms, with or without
- modification, are permitted provided that the following conditions
- are met:
- 1. Redistributions of source code must retain the above copyright
- notice, this list of conditions and the following disclaimer.
- 2. Redistributions in binary form must reproduce the above
- copyright notice, this list of conditions and the following
- disclaimer in the documentation and/or other materials
- provided with the distribution.
-
- THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
- ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
- LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
- A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL ANY
- CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,
- EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
- PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR
- PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
- OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
- NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
- SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
*====================================================================*/
/*
* otsutest2.c
*
* This demonstrates the usefulness of the modified version of Otsu
* for thresholding an image that doesn't have a well-defined
* background color.
*
* Standard Otsu binarization is done with scorefract = 0.0, which
* returns the threshold at the maximum value of the score. However.
* this value is up on the shoulder of the background, and its
* use causes some of the dark background to be binarized as foreground.
*
* Using the modified Otsu with scorefract = 0.1 returns a threshold
* at the lowest value of this histogram such that the score
* is at least 0.9 times the maximum value of the score. This allows
* the threshold to be taken in the histogram minimum between
* the fg and bg peaks, producing a much cleaner binarization.
*/
#ifdef HAVE_CONFIG_H
#include <config_auto.h>
#endif /* HAVE_CONFIG_H */
#include "allheaders.h"
int main(int argc,
char **argv)
{
char textstr[256];
l_int32 i, thresh, fgval, bgval;
l_float32 scorefract;
L_BMF *bmf;
PIX *pixs, *pixb, *pixg, *pixp, *pix1, *pix2, *pix3;
PIXA *pixa1, *pixad;
setLeptDebugOK(1);
lept_mkdir("lept/otsu");
pixs = pixRead("1555.007.jpg");
pixg = pixConvertTo8(pixs, 0);
bmf = bmfCreate(NULL, 8);
pixad = pixaCreate(0);
for (i = 0; i < 3; i++) {
pixa1 = pixaCreate(2);
scorefract = 0.1 * i;
/* Get a 1 bpp version; use a single tile */
pixOtsuAdaptiveThreshold(pixg, 2000, 2000, 0, 0, scorefract,
NULL, &pixb);
pixaAddPix(pixa1, pixg, L_COPY);
pixaAddPix(pixa1, pixb, L_INSERT);
/* Show the histogram of gray values and the split location */
pixSplitDistributionFgBg(pixg, scorefract, 1,
&thresh, &fgval, &bgval, &pixp);
lept_stderr("thresh = %d, fgval = %d, bgval = %d\n",
thresh, fgval, bgval);
pixaAddPix(pixa1, pixp, L_INSERT);
/* Join these together and add some text */
pix1 = pixaDisplayTiledInColumns(pixa1, 3, 1.0, 20, 2);
snprintf(textstr, sizeof(textstr),
"Scorefract = %3.1f ........... Thresh = %d", scorefract, thresh);
pix2 = pixAddSingleTextblock(pix1, bmf, textstr, 0x00ff0000,
L_ADD_BELOW, NULL);
/* Save and display the result */
pixaAddPix(pixad, pix2, L_INSERT);
snprintf(textstr, sizeof(textstr), "/tmp/lept/otsu/%03d.png", i);
pixWrite(textstr, pix2, IFF_PNG);
pixDisplay(pix2, 100, 100);
pixDestroy(&pix1);
pixaDestroy(&pixa1);
}
/* Use a smaller tile for Otsu */
for (i = 0; i < 2; i++) {
scorefract = 0.1 * i;
pixOtsuAdaptiveThreshold(pixg, 300, 300, 0, 0, scorefract,
NULL, &pixb);
pix1 = pixAddBlackOrWhiteBorder(pixb, 2, 2, 2, 2, L_GET_BLACK_VAL);
pix2 = pixScale(pix1, 0.5, 0.5);
snprintf(textstr, sizeof(textstr),
"Scorefract = %3.1f", scorefract);
pix3 = pixAddSingleTextblock(pix2, bmf, textstr, 1,
L_ADD_BELOW, NULL);
pixaAddPix(pixad, pix3, L_INSERT);
pixDestroy(&pixb);
pixDestroy(&pix1);
pixDestroy(&pix2);
}
lept_stderr("Writing to: /tmp/lept/otsu/result1.pdf\n");
pixaConvertToPdf(pixad, 75, 1.0, 0, 0, "Otsu thresholding",
"/tmp/lept/otsu/result1.pdf");
bmfDestroy(&bmf);
pixDestroy(&pixs);
pixDestroy(&pixg);
pixaDestroy(&pixad);
return 0;
}
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