1 files changed, 156 insertions, 0 deletions
diff --git a/converter/other/hdifftopam.c b/converter/other/hdifftopam.c
new file mode 100644
index 00000000..444d6068
--- /dev/null
+++ b/converter/other/hdifftopam.c
@@ -0,0 +1,156 @@
+/******************************************************************************
+                                hdifftopam
+*******************************************************************************
+  This program recovers a PAM image from a horizontal difference images 
+  such as created by Pamtohdiff.
+
+  By Bryan Henderson, San Jose, CA 2002.04.15.
+******************************************************************************/
+#include <string.h>
+#include <stdio.h>
+
+#include "pam.h"
+#include "shhopt.h"
+#include "nstring.h"
+
+struct cmdlineInfo {
+    /* All the information the user supplied in the command line,
+       in a form easy for the program to use.
+    */
+    const char *inputFilespec;  /* Filespecs of input files */
+    unsigned int pnm;
+    unsigned int verbose;
+};
+
+
+
+static void
+parseCommandLine(int argc, char ** argv,
+                 struct cmdlineInfo * const cmdlineP) {
+/*----------------------------------------------------------------------------
+   Note that the file spec array we return is stored in the storage that
+   was passed to us as the argv array.
+-----------------------------------------------------------------------------*/
+    optEntry *option_def = malloc( 100*sizeof( optEntry ) );
+        /* Instructions to optParseOptions3 on how to parse our options.
+         */
+    optStruct3 opt;
+
+    unsigned int option_def_index;
+
+    option_def_index = 0;   /* incremented by OPTENTRY */
+    OPTENT3(0, "pnm",       OPT_FLAG,    NULL, &cmdlineP->pnm,      0);
+    OPTENT3(0, "verbose",   OPT_FLAG,    NULL, &cmdlineP->verbose,  0);
+
+    opt.opt_table = option_def;
+    opt.short_allowed = FALSE;  /* We have no short (old-fashioned) options */
+    opt.allowNegNum = FALSE;  /* We have no parms that are negative numbers */
+
+    optParseOptions3(&argc, argv, opt, sizeof(opt), 0);
+        /* Uses and sets argc, argv, and some of *cmdlineP and others. */
+
+    if (argc-1 < 1)
+        cmdlineP->inputFilespec = "-";
+    else if (argc-1 == 1)
+        cmdlineP->inputFilespec = argv[1];
+    else
+        pm_error("Too many arguments.");
+}
+
+
+
+static void
+makePnm(struct pam * const pamP) {
+
+    switch (pamP->depth) {
+    case 1: 
+        pamP->format = PGM_FORMAT;
+        break;
+    case 3:
+        pamP->format = PPM_FORMAT;
+        break;
+    default:
+        pm_error("Input depth (%d) does not correspond to a PNM format.",
+                 pamP->depth);
+    }
+}
+
+
+
+static void
+    describeOutput(struct pam const pam) {
+
+    pm_message("Output is %d x %d x %d, maxval %u",
+               pam.width, pam.height, pam.depth, (unsigned int) pam.maxval);
+}
+
+
+
+int 
+main(int argc, char *argv[]) {
+    FILE *ifP;
+    struct cmdlineInfo cmdline;
+    struct pam diffpam, outpam;
+    unsigned int row;
+    tuple * diffrow;
+    tuple * outrow;
+    tuple * prevrow;
+
+    pnm_init( &argc, argv );
+
+    parseCommandLine(argc, argv, &cmdline);
+
+    ifP = pm_openr(cmdline.inputFilespec);
+
+    pnm_readpaminit(ifP, &diffpam, PAM_STRUCT_SIZE(tuple_type));
+
+    if (diffpam.format != PAM_FORMAT) 
+        pm_error("Input must be a PAM file, not PNM");
+    else if (!STREQ(diffpam.tuple_type, "hdiff")) 
+        pm_error("Input tuple type is '%s'.  Must be 'hdiff'",
+                 diffpam.tuple_type);
+
+    outpam = diffpam;
+    outpam.file = stdout;
+    strcpy(outpam.tuple_type, "unhdiff");
+
+    if (cmdline.verbose)
+        describeOutput(outpam);
+    if (cmdline.pnm)
+        makePnm(&outpam);
+
+    pnm_writepaminit(&outpam);
+
+    diffrow = pnm_allocpamrow(&diffpam);
+    outrow =  pnm_allocpamrow(&outpam);
+    prevrow = pnm_allocpamrow(&diffpam);
+
+    pnm_setpamrow(&diffpam, prevrow, 0);
+
+    {
+        unsigned int const bias = diffpam.maxval/2;
+        
+        for (row = 0; row < diffpam.height; ++row) {
+            unsigned int col;
+            pnm_readpamrow(&diffpam, diffrow);
+            for (col = 0; col < diffpam.width; ++col) {
+                unsigned int plane;
+                for (plane = 0; plane < diffpam.depth; ++plane) {
+                    sample const prevSample = prevrow[col][plane];
+                    sample const diffSample = diffrow[col][plane];
+                    
+                    outrow[col][plane] = 
+                        (-bias + prevSample + diffSample) % (outpam.maxval+1);
+                    prevrow[col][plane] = outrow[col][plane];
+                }
+            }
+            pnm_writepamrow(&outpam, outrow);
+        }
+    }
+    pnm_freepamrow(prevrow);
+    pnm_freepamrow(outrow);
+    pnm_freepamrow(diffrow);
+
+    exit(0);
+}
+