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/* pnminterp - scale up portable anymap by interpolating between pixels.
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* Copyright (C) 1998,2000 Russell Marks.
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License as published by
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* the Free Software Foundation; either version 2 of the License, or (at
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* your option) any later version.
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
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/* drop one (source) pixel at right/bottom edges. */
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/* interpolate right/bottom edge pixels to black. */
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/* don't interpolate right/bottom edge pixels
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(default, and what zgv does). */
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/* All the information the user supplied in the command line,
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in a form easy for the program to use.
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char *input_filespec; /* Filespecs of input files */
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enum an_edge_mode edge_mode;
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/* A "black" tuple. Unless our input image is PBM, PGM, or PPM, we
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don't really know what "black" means, so this is just something
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arbitrary in that case.
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parse_command_line(int argc, char ** argv,
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struct cmdline_info *cmdline_p) {
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/*----------------------------------------------------------------------------
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Note that the file spec array we return is stored in the storage that
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was passed to us as the argv array.
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-----------------------------------------------------------------------------*/
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optStruct3 opt; /* set by OPTENT3 */
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optEntry *option_def = malloc(100*sizeof(optStruct));
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unsigned int option_def_index;
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unsigned int blackedge;
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unsigned int dropedge;
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unsigned int xscale_spec;
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unsigned int yscale_spec;
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option_def_index = 0; /* incremented by OPTENTRY */
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OPTENT3('b', "blackedge", OPT_FLAG, NULL, &blackedge, 0);
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OPTENT3('d', "dropedge", OPT_FLAG, NULL, &dropedge, 0);
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OPTENT3(0, "xscale", OPT_UINT,
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&cmdline_p->xscale, &xscale_spec, 0);
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OPTENT3(0, "yscale", OPT_UINT,
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&cmdline_p->yscale, &yscale_spec, 0);
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opt.opt_table = option_def;
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opt.short_allowed = FALSE; /* We have some short (old-fashioned) options */
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opt.allowNegNum = FALSE; /* We have no parms that are negative numbers */
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pm_optParseOptions3(&argc, argv, opt, sizeof(opt), 0);
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/* Uses and sets argc, argv, and some of *cmdline_p and others. */
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if (blackedge && dropedge)
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pm_error("Can't specify both -blackedge and -dropedge options.");
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cmdline_p->edge_mode = EDGE_INTERP_TO_BLACK;
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cmdline_p->edge_mode = EDGE_DROP;
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cmdline_p->edge_mode = EDGE_NON_INTERP;
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if (xscale_spec && cmdline_p->xscale == 0)
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pm_error("You specified zero for the X scale factor.");
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if (yscale_spec && cmdline_p->yscale == 0)
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pm_error("You specified zero for the Y scale factor.");
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if (xscale_spec && !yscale_spec)
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cmdline_p->yscale = 1;
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if (yscale_spec && !xscale_spec)
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cmdline_p->xscale = 1;
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if (!(xscale_spec || yscale_spec)) {
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/* scale must be specified in an argument */
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if ((argc-1) != 1 && (argc-1) != 2)
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pm_error("Wrong number of arguments (%d). Without scale options, "
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"you must supply 1 or 2 arguments: scale and "
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"optional file specification", argc-1);
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char *endptr; /* ptr to 1st invalid character in scale arg */
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scale = strtol(argv[1], &endptr, 10);
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if (*argv[1] == '\0')
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pm_error("Scale argument is a null string. "
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"Must be a number.");
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else if (*endptr != '\0')
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pm_error("Scale argument contains non-numeric character '%c'.",
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pm_error("Scale argument must be at least 2. "
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"You specified %d", scale);
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cmdline_p->xscale = scale;
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cmdline_p->yscale = scale;
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cmdline_p->input_filespec = argv[2];
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cmdline_p->input_filespec = "-";
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/* No scale argument allowed */
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pm_error("Too many arguments (%d). With a scale option, "
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"the only argument is the "
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"optional file specification", argc-1);
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cmdline_p->input_filespec = argv[1];
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cmdline_p->input_filespec = "-";
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stretch_line(struct pam * const inpamP,
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const tuple * const line, const tuple * const line_stretched,
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unsigned int const scale, enum an_edge_mode const edge_mode) {
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/*----------------------------------------------------------------------------
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Stretch the line of tuples 'line' into the output buffer 'line_stretched',
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-----------------------------------------------------------------------------*/
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/* normalizing factor to make fractions representable as integers.
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E.g. if sisize = 100, one half is represented as 50.
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scaleincr = sisize/scale; /* (1/scale, normalized) */
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outcol = 0; /* initial value */
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for (col = 0; col < inpamP->width; ++col) {
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/* The fraction of the way we are from curline to nextline,
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normalized by sisize.
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if (col >= inpamP->width-1) {
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/* We're at the edge. There is no column to the right with which
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/* No output column needed for this input column */
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case EDGE_INTERP_TO_BLACK: {
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for (pos = 0; pos < sisize; pos += scaleincr) {
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for (plane = 0; plane < inpamP->depth; ++plane)
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line_stretched[outcol][plane] =
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(line[col][plane] * (sisize-pos)) / sisize;
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case EDGE_NON_INTERP: {
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for (pos = 0; pos < sisize; pos += scaleincr) {
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for (plane = 0; plane < inpamP->depth; ++plane)
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line_stretched[outcol][plane] = line[col][plane];
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pm_error("INTERNAL ERROR: invalid value for edge_mode");
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/* Interpolate with the next input column to the right */
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for (pos = 0; pos < sisize; pos += scaleincr) {
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for (plane = 0; plane < inpamP->depth; ++plane)
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line_stretched[outcol][plane] =
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(line[col][plane] * (sisize-pos)
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+ line[col+1][plane] * pos) / sisize;
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write_interp_rows(struct pam * const outpamP,
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const tuple * const curline,
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const tuple * const nextline,
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tuple * const outbuf,
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/*----------------------------------------------------------------------------
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Write out 'scale' rows, being 'curline' followed by rows that are
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interpolated between 'curline' and 'nextline'.
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-----------------------------------------------------------------------------*/
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unsigned int scaleincr;
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while(sisize<256) sisize+=scale;
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scaleincr=sisize/scale;
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for (pos = 0; pos < sisize; pos += scaleincr) {
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for (col = 0; col < outpamP->width; ++col) {
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for (plane = 0; plane < outpamP->depth; ++plane)
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outbuf[col][plane] = (curline[col][plane] * (sisize-pos)
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+ nextline[col][plane] * pos) / sisize;
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pnm_writepamrow(outpamP, outbuf);
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swap_buffers(tuple ** const buffer1P, tuple ** const buffer2P) {
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/* Advance "next" line to "current" line by switching
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*buffer1P = *buffer2P;
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stretch(struct pam * const inpamP, struct pam * const outpamP,
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int const xscale, int const yscale,
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enum an_edge_mode const edge_mode) {
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tuple *linebuf1, *linebuf2; /* Input buffers for two rows at a time */
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tuple *curline, *nextline; /* Pointers to one of the two above buffers */
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/* And the stretched versions: */
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tuple *stretched_linebuf1, *stretched_linebuf2;
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tuple *curline_stretched, *nextline_stretched;
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tuple *outbuf; /* One-row output buffer */
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unsigned int rowsToStretch;
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linebuf1 = pnm_allocpamrow(inpamP);
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linebuf2 = pnm_allocpamrow(inpamP);
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stretched_linebuf1 = pnm_allocpamrow(outpamP);
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stretched_linebuf2 = pnm_allocpamrow(outpamP);
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outbuf = pnm_allocpamrow(outpamP);
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curline_stretched = stretched_linebuf1;
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nextline_stretched = stretched_linebuf2;
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pnm_readpamrow(inpamP, curline);
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stretch_line(inpamP, curline, curline_stretched, xscale, edge_mode);
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if (edge_mode == EDGE_DROP)
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rowsToStretch = inpamP->height - 1;
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rowsToStretch = inpamP->height;
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for (row = 0; row < rowsToStretch; row++) {
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if (row == inpamP->height-1) {
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/* last line is about to be output. there is no further
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* `next line'. if EDGE_DROP, we stop here, with output
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* of rows-1 rows. if EDGE_INTERP_TO_BLACK we make next
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* line black. if EDGE_NON_INTERP (default) we make it a
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* copy of the current line.
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case EDGE_INTERP_TO_BLACK: {
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for (col = 0; col < outpamP->width; col++)
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nextline_stretched[col] = blackTuple;
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case EDGE_NON_INTERP: {
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/* EDGE_NON_INTERP */
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for (col = 0; col < outpamP->width; col++)
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nextline_stretched[col] = curline_stretched[col];
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pm_error("INTERNAL ERROR: processing last row, but "
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"edge_mode is EDGE_DROP.");
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pnm_readpamrow(inpamP, nextline);
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stretch_line(inpamP, nextline, nextline_stretched, xscale,
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/* interpolate curline towards nextline into outbuf */
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write_interp_rows(outpamP, curline_stretched, nextline_stretched,
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swap_buffers(&curline, &nextline);
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swap_buffers(&curline_stretched, &nextline_stretched);
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pnm_freerow(stretched_linebuf2);
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pnm_freerow(stretched_linebuf1);
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pnm_freerow(linebuf2);
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pnm_freerow(linebuf1);
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main(int argc,char *argv[]) {
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struct cmdline_info cmdline;
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struct pam inpam, outpam;
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pnm_init(&argc, argv);
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parse_command_line(argc, argv, &cmdline);
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ifp = pm_openr(cmdline.input_filespec);
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pnm_readpaminit(ifp, &inpam, sizeof(inpam));
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pm_error("Image is too narrow. Must be at least 2 columns.");
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if (inpam.height < 2)
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pm_error("Image is too short. Must be at least 2 lines.");
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outpam = inpam; /* initial value */
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outpam.file = stdout;
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if (PNM_FORMAT_TYPE(inpam.format) == PBM_TYPE) {
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outpam.format = PGM_TYPE;
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/* usual filter message when reading PBM but writing PGM: */
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pm_message("pamstretch: promoting from PBM to PGM");
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outpam.format = PPM_TYPE;
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unsigned int const dropped = cmdline.edge_mode == EDGE_DROP ? 1 : 0;
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outpam.width = (inpam.width - dropped) * cmdline.xscale;
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outpam.height = (inpam.height - dropped) * cmdline.yscale;
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pnm_writepaminit(&outpam);
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createBlackTuple(&outpam, &blackTuple);
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stretch(&inpam, &outpam,
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cmdline.xscale, cmdline.yscale, cmdline.edge_mode);
added
removed
pnm/pamstretch.c
