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-rw-r--r--src/trace/filterset.cpp428
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diff --git a/src/trace/filterset.cpp b/src/trace/filterset.cpp
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+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * Some filters for Potrace in Inkscape
+ *
+ * Authors:
+ * Bob Jamison <rjamison@titan.com>
+ * Stéphane Gimenez <dev@gim.name>
+ *
+ * Copyright (C) 2004-2006 Authors
+ *
+ * Released under GNU GPL v2+, read the file 'COPYING' for more information.
+ */
+
+#include <cstdio>
+#include <cstdlib>
+
+#include "imagemap-gdk.h"
+#include "filterset.h"
+#include "quantize.h"
+
+/*#########################################################################
+### G A U S S I A N (smoothing)
+#########################################################################*/
+
+/**
+ *
+ */
+static int gaussMatrix[] =
+{
+ 2, 4, 5, 4, 2,
+ 4, 9, 12, 9, 4,
+ 5, 12, 15, 12, 5,
+ 4, 9, 12, 9, 4,
+ 2, 4, 5, 4, 2
+};
+
+
+/**
+ *
+ */
+GrayMap *grayMapGaussian(GrayMap *me)
+{
+ int width = me->width;
+ int height = me->height;
+ int firstX = 2;
+ int lastX = width-3;
+ int firstY = 2;
+ int lastY = height-3;
+
+ GrayMap *newGm = GrayMapCreate(width, height);
+ if (!newGm)
+ return nullptr;
+
+ for (int y = 0 ; y<height ; y++)
+ {
+ for (int x = 0 ; x<width ; x++)
+ {
+ /* image boundaries */
+ if (x<firstX || x>lastX || y<firstY || y>lastY)
+ {
+ newGm->setPixel(newGm, x, y, me->getPixel(me, x, y));
+ continue;
+ }
+
+ /* all other pixels */
+ int gaussIndex = 0;
+ unsigned long sum = 0;
+ for (int i= y-2 ; i<=y+2 ; i++)
+ {
+ for (int j= x-2; j<=x+2 ; j++)
+ {
+ int weight = gaussMatrix[gaussIndex++];
+ sum += me->getPixel(me, j, i) * weight;
+ }
+ }
+ sum /= 159;
+ newGm->setPixel(newGm, x, y, sum);
+ }
+ }
+
+ return newGm;
+}
+
+
+
+
+
+/**
+ *
+ */
+RgbMap *rgbMapGaussian(RgbMap *me)
+{
+ int width = me->width;
+ int height = me->height;
+ int firstX = 2;
+ int lastX = width-3;
+ int firstY = 2;
+ int lastY = height-3;
+
+ RgbMap *newGm = RgbMapCreate(width, height);
+ if (!newGm)
+ return nullptr;
+
+ for (int y = 0 ; y<height ; y++)
+ {
+ for (int x = 0 ; x<width ; x++)
+ {
+ /* image boundaries */
+ if (x<firstX || x>lastX || y<firstY || y>lastY)
+ {
+ newGm->setPixelRGB(newGm, x, y, me->getPixel(me, x, y));
+ continue;
+ }
+
+ /* all other pixels */
+ int gaussIndex = 0;
+ int sumR = 0;
+ int sumG = 0;
+ int sumB = 0;
+ for (int i= y-2 ; i<=y+2 ; i++)
+ {
+ for (int j= x-2; j<=x+2 ; j++)
+ {
+ int weight = gaussMatrix[gaussIndex++];
+ RGB rgb = me->getPixel(me, j, i);
+ sumR += weight * (int)rgb.r;
+ sumG += weight * (int)rgb.g;
+ sumB += weight * (int)rgb.b;
+ }
+ }
+ RGB rout;
+ rout.r = ( sumR / 159 ) & 0xff;
+ rout.g = ( sumG / 159 ) & 0xff;
+ rout.b = ( sumB / 159 ) & 0xff;
+ newGm->setPixelRGB(newGm, x, y, rout);
+ }
+ }
+
+ return newGm;
+
+}
+
+
+
+
+/*#########################################################################
+### C A N N Y E D G E D E T E C T I O N
+#########################################################################*/
+
+
+static int sobelX[] =
+{
+ -1, 0, 1 ,
+ -2, 0, 2 ,
+ -1, 0, 1
+};
+
+static int sobelY[] =
+{
+ 1, 2, 1 ,
+ 0, 0, 0 ,
+ -1, -2, -1
+};
+
+
+
+/**
+ * Perform Sobel convolution on a GrayMap
+ */
+static GrayMap *grayMapSobel(GrayMap *gm,
+ double dLowThreshold, double dHighThreshold)
+{
+ int width = gm->width;
+ int height = gm->height;
+ int firstX = 1;
+ int lastX = width-2;
+ int firstY = 1;
+ int lastY = height-2;
+
+ GrayMap *newGm = GrayMapCreate(width, height);
+ if (!newGm)
+ return nullptr;
+
+ for (int y = 0 ; y<height ; y++)
+ {
+ for (int x = 0 ; x<width ; x++)
+ {
+ unsigned long sum = 0;
+ /* image boundaries */
+ if (x<firstX || x>lastX || y<firstY || y>lastY)
+ {
+ sum = 0;
+ }
+ else
+ {
+ /* ### SOBEL FILTERING #### */
+ long sumX = 0;
+ long sumY = 0;
+ int sobelIndex = 0;
+ for (int i= y-1 ; i<=y+1 ; i++)
+ {
+ for (int j= x-1; j<=x+1 ; j++)
+ {
+ sumX += gm->getPixel(gm, j, i) *
+ sobelX[sobelIndex++];
+ }
+ }
+
+ sobelIndex = 0;
+ for (int i= y-1 ; i<=y+1 ; i++)
+ {
+ for (int j= x-1; j<=x+1 ; j++)
+ {
+ sumY += gm->getPixel(gm, j, i) *
+ sobelY[sobelIndex++];
+ }
+ }
+ /*### GET VALUE ### */
+ sum = abs(sumX) + abs(sumY);
+
+ if (sum > 765)
+ sum = 765;
+
+#if 0
+ /*### GET ORIENTATION (slow, pedantic way) ### */
+ double orient = 0.0;
+ if (sumX==0)
+ {
+ if (sumY==0)
+ orient = 0.0;
+ else if (sumY<0)
+ {
+ sumY = -sumY;
+ orient = 90.0;
+ }
+ else
+ orient = 90.0;
+ }
+ else
+ {
+ orient = 57.295779515 * atan2( ((double)sumY),((double)sumX) );
+ if (orient < 0.0)
+ orient += 180.0;
+ }
+
+ /*### GET EDGE DIRECTION ### */
+ int edgeDirection = 0;
+ if (orient < 22.5)
+ edgeDirection = 0;
+ else if (orient < 67.5)
+ edgeDirection = 45;
+ else if (orient < 112.5)
+ edgeDirection = 90;
+ else if (orient < 157.5)
+ edgeDirection = 135;
+#else
+ /*### GET EDGE DIRECTION (fast way) ### */
+ int edgeDirection = 0; /*x,y=0*/
+ if (sumX==0)
+ {
+ if (sumY!=0)
+ edgeDirection = 90;
+ }
+ else
+ {
+ /*long slope = sumY*1024/sumX;*/
+ long slope = (sumY << 10)/sumX;
+ if (slope > 2472 || slope< -2472) /*tan(67.5)*1024*/
+ edgeDirection = 90;
+ else if (slope > 414) /*tan(22.5)*1024*/
+ edgeDirection = 45;
+ else if (slope < -414) /*-tan(22.5)*1024*/
+ edgeDirection = 135;
+ }
+
+#endif
+ /* printf("%ld %ld %f %d\n", sumX, sumY, orient, edgeDirection); */
+
+ /*### Get two adjacent pixels in edge direction ### */
+ unsigned long leftPixel;
+ unsigned long rightPixel;
+ if (edgeDirection == 0)
+ {
+ leftPixel = gm->getPixel(gm, x-1, y);
+ rightPixel = gm->getPixel(gm, x+1, y);
+ }
+ else if (edgeDirection == 45)
+ {
+ leftPixel = gm->getPixel(gm, x-1, y+1);
+ rightPixel = gm->getPixel(gm, x+1, y-1);
+ }
+ else if (edgeDirection == 90)
+ {
+ leftPixel = gm->getPixel(gm, x, y-1);
+ rightPixel = gm->getPixel(gm, x, y+1);
+ }
+ else /*135 */
+ {
+ leftPixel = gm->getPixel(gm, x-1, y-1);
+ rightPixel = gm->getPixel(gm, x+1, y+1);
+ }
+
+ /*### Compare current value to adjacent pixels ### */
+ /*### if less that either, suppress it ### */
+ if (sum < leftPixel || sum < rightPixel)
+ sum = 0;
+ else
+ {
+ unsigned long highThreshold =
+ (unsigned long)(dHighThreshold * 765.0);
+ unsigned long lowThreshold =
+ (unsigned long)(dLowThreshold * 765.0);
+ if (sum >= highThreshold)
+ sum = 765; /* EDGE. 3*255 this needs to be settable */
+ else if (sum < lowThreshold)
+ sum = 0; /* NONEDGE */
+ else
+ {
+ if ( gm->getPixel(gm, x-1, y-1)> highThreshold ||
+ gm->getPixel(gm, x , y-1)> highThreshold ||
+ gm->getPixel(gm, x+1, y-1)> highThreshold ||
+ gm->getPixel(gm, x-1, y )> highThreshold ||
+ gm->getPixel(gm, x+1, y )> highThreshold ||
+ gm->getPixel(gm, x-1, y+1)> highThreshold ||
+ gm->getPixel(gm, x , y+1)> highThreshold ||
+ gm->getPixel(gm, x+1, y+1)> highThreshold)
+ sum = 765; /* EDGE fix me too */
+ else
+ sum = 0; /* NONEDGE */
+ }
+ }
+
+
+ }/* else */
+ if (sum==0) /* invert light & dark */
+ sum = 765;
+ else
+ sum = 0;
+ newGm->setPixel(newGm, x, y, sum);
+ }/* for (x) */
+ }/* for (y) */
+
+ return newGm;
+}
+
+
+
+
+
+/**
+ *
+ */
+GrayMap *
+grayMapCanny(GrayMap *gm, double lowThreshold, double highThreshold)
+{
+ if (!gm)
+ return nullptr;
+
+ GrayMap *cannyGm = grayMapSobel(gm, lowThreshold, highThreshold);
+ if (!cannyGm)
+ return nullptr;
+ /*cannyGm->writePPM(cannyGm, "canny.ppm");*/
+
+ return cannyGm;
+}
+
+
+
+/*#########################################################################
+### Q U A N T I Z A T I O N
+#########################################################################*/
+
+/**
+ * Experimental. Work on this later
+ */
+GrayMap *quantizeBand(RgbMap *rgbMap, int nrColors)
+{
+
+ RgbMap *gaussMap = rgbMapGaussian(rgbMap);
+ if (!gaussMap)
+ return nullptr;
+ //gaussMap->writePPM(gaussMap, "rgbgauss.ppm");
+
+ IndexedMap *qMap = rgbMapQuantize(gaussMap, nrColors);
+ gaussMap->destroy(gaussMap);
+ if (!qMap)
+ return nullptr;
+ //qMap->writePPM(qMap, "rgbquant.ppm");
+
+ GrayMap *gm = GrayMapCreate(rgbMap->width, rgbMap->height);
+ if (!gm)
+ return nullptr;
+
+ // RGB is quantized. There should now be a small set of (R+G+B)
+ for (int y=0 ; y<qMap->height ; y++)
+ {
+ for (int x=0 ; x<qMap->width ; x++)
+ {
+ RGB rgb = qMap->getPixelValue(qMap, x, y);
+ int sum = rgb.r + rgb.g + rgb.b;
+ if (sum & 1)
+ sum = 765;
+ else
+ sum = 0;
+ // printf("%d %d %d : %d\n", rgb.r, rgb.g, rgb.b, index);
+ gm->setPixel(gm, x, y, sum);
+ }
+ }
+
+ qMap->destroy(qMap);
+
+ return gm;
+}
+
+
+/*#########################################################################
+### E N D O F F I L E
+#########################################################################*/
+
+
+
+
+
+
+
+
+
+
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