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Diffstat (limited to 'leptonica/prog/otsutest2.c')
-rw-r--r--leptonica/prog/otsutest2.c129
1 files changed, 129 insertions, 0 deletions
diff --git a/leptonica/prog/otsutest2.c b/leptonica/prog/otsutest2.c
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+++ b/leptonica/prog/otsutest2.c
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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;
+}