1 files changed, 203 insertions, 0 deletions
diff --git a/editor/pamedge.c b/editor/pamedge.c
new file mode 100644
index 00000000..e73c9d17
--- /dev/null
+++ b/editor/pamedge.c
@@ -0,0 +1,203 @@
+/* pnmedge.c - edge-detection
+**
+** Copyright (C) 1989 by Jef Poskanzer.
+**   modified for pnm by Peter Kirchgessner, 1995.
+**
+** Permission to use, copy, modify, and distribute this software and its
+** documentation for any purpose and without fee is hereby granted, provided
+** that the above copyright notice appear in all copies and that both that
+** copyright notice and this permission notice appear in supporting
+** documentation.  This software is provided "as is" without express or
+** implied warranty.
+*/
+
+#include <math.h>
+
+#include "pm_c_util.h"
+#include "pam.h"
+
+
+
+static void
+writeBlackRow(struct pam * const pamP) {
+
+    tuple * const tuplerow = pnm_allocpamrow(pamP);
+
+    unsigned int col;
+    for (col = 0; col < pamP->width; ++col) {
+        unsigned int plane;
+        for (plane = 0; plane < pamP->depth; ++plane)
+            tuplerow[col][plane] = 0;
+    }
+    pnm_writepamrow(pamP, tuplerow);
+} 
+
+
+
+static void
+rotateRows(tuple ** const row0P,
+           tuple ** const row1P,
+           tuple ** const row2P) {
+    /* Rotate rows. */
+    tuple * const formerRow0 = *row0P;
+    *row0P = *row1P;
+    *row1P = *row2P;
+    *row2P = formerRow0;
+}
+
+
+
+static long
+horizGradient(tuple *      const tuplerow,
+              unsigned int const col,
+              unsigned int const plane) {
+
+    return (long)tuplerow[col+1][plane] - (long)tuplerow[col-1][plane];
+}
+
+
+
+static long
+horizAvg(tuple *      const tuplerow,
+         unsigned int const col,
+         unsigned int const plane) {
+
+    return
+        1 * (long)tuplerow[col-1][plane] +
+        2 * (long)tuplerow[col  ][plane] +
+        1 * (long)tuplerow[col+1][plane];
+
+}
+
+
+
+static void
+computeOneRow(struct pam * const inpamP,
+              struct pam * const outpamP,
+              tuple *      const row0,
+              tuple *      const row1,
+              tuple *      const row2,
+              tuple *      const orow) {
+/*----------------------------------------------------------------------------
+   Compute an output row from 3 input rows.
+
+   The input rows must have the same maxval as the output row.
+-----------------------------------------------------------------------------*/
+    unsigned int plane;
+
+    for (plane = 0; plane < inpamP->depth; ++plane) {
+        unsigned int col;
+
+        /* Left column is black */
+        orow[0][plane] = 0;
+
+        for (col = 1; col < inpamP->width - 1; ++col) {
+            double const grad1 = 
+                1 * horizGradient(row0, col, plane) +
+                2 * horizGradient(row1, col, plane) +
+                1 * horizGradient(row2, col, plane);
+
+            double const grad2 = 
+                horizAvg(row2, col, plane) - horizAvg(row0, col, plane);
+
+            double const gradient = sqrt(SQR(grad1) + SQR(grad2));
+
+            /* apply arbitrary scaling factor and maxval clipping */
+            orow[col][plane] = MIN(outpamP->maxval, (long)(gradient / 1.8));
+
+            /* Right column is black */
+            orow[inpamP->width - 1][plane] = 0;
+        }
+    }
+}
+
+
+
+static void
+writeMiddleRows(struct pam * const inpamP,
+                struct pam * const outpamP) {
+
+    tuple *row0, *row1, *row2;
+    tuple *orow, *irow;
+    unsigned int row;
+
+    irow = pnm_allocpamrow(inpamP);
+    orow = pnm_allocpamrow(outpamP);
+    row0 = pnm_allocpamrow(outpamP);
+    row1 = pnm_allocpamrow(outpamP);
+    row2 = pnm_allocpamrow(outpamP);
+
+    /* Read in the first two rows. */
+    pnm_readpamrow(inpamP, irow);
+    pnm_scaletuplerow(inpamP, row0, irow, outpamP->maxval);
+    pnm_readpamrow(inpamP, irow);
+    pnm_scaletuplerow(inpamP, row1, irow, outpamP->maxval);
+
+    pm_message("row1[0][0]=%lu", row1[0][0]);
+
+    for (row = 1; row < inpamP->height - 1; ++row) {
+        /* Read in the next row and write out the current row.  */
+
+        pnm_readpamrow(inpamP, irow);
+        pnm_scaletuplerow(inpamP, row2, irow, outpamP->maxval);
+
+        computeOneRow(inpamP, outpamP, row0, row1, row2, orow);
+
+        pnm_writepamrow(outpamP, orow);
+
+        rotateRows(&row0, &row1, &row2);
+    }
+    pnm_freepamrow(orow);
+    pnm_freepamrow(row2);
+    pnm_freepamrow(row1);
+    pnm_freepamrow(row0);
+}
+
+
+
+int
+main(int argc, char *argv[]) {
+    FILE *ifP;
+    struct pam inpam, outpam;
+
+    pnm_init( &argc, argv );
+
+    if (argc-1 == 1) 
+        ifP = pm_openr(argv[1]);
+    else if (argc-1 == 0)
+        ifP = stdin;
+    else
+        pm_error("Too many arguments.  Program takes at most 1 argument: "
+                 "input file name");
+
+    pnm_readpaminit(ifP, &inpam, PAM_STRUCT_SIZE(tuple_type));
+    if (inpam.width < 3)
+        pm_error("Image is %u columns wide.  It must be at least 3.",
+                 inpam.width);
+    if (inpam.height < 3)
+        pm_error("Image is %u rows high.  It must be at least 3.",
+                 inpam.height);
+
+    outpam = inpam;
+    outpam.file = stdout;
+    if (PAM_FORMAT_TYPE(inpam.format) == PBM_TYPE) {
+        outpam.format = PGM_FORMAT;
+        outpam.maxval = 255;
+    }
+
+    pnm_writepaminit(&outpam);
+
+    /* First row is black: */
+    writeBlackRow(&outpam      );
+
+    writeMiddleRows(&inpam, &outpam);
+
+    pm_close(ifP);
+
+    /* Last row is black: */
+    writeBlackRow(&outpam);
+
+    pm_close(stdout);
+
+    return 0;
+}