NAME

       farbfeld — suckless image format

DESCRIPTION

       farbfeld  is  a  lossless  image  format which is easy to parse, pipe and compress.  It has the following
       format:

       BYTES    DESCRIPTION
       8        "farbfeld" magic value
       4        32-Bit BE unsigned integer (width)
       4        32-Bit BE unsigned integer (height)
       [2222]   4*16-Bit BE unsigned integers [RGBA] / pixel, row-major

       The RGB-data should be sRGB for best interoperability and not alpha-premultiplied.

USAGE

       farbfeld provides the tools 2ff(1), jpg2ff(1), png2ff(1) and ff2jpg(1), ff2pam(1),  ff2png(1),  ff2ppm(1)
       to convert to and from farbfeld images respectively.

       bzip2(1)  is  recommended  for  compression,  giving results comparable with PNG for photographs and much
       better results for other image types.

       The file extension is ".ff" and compression extensions shall be appended (e.g. ".ff.bz2").

MOTIVATION

       farbfeld was created because the author was not satisfied with the boilerplate  and  inherent  complexity
       involved in handling common image formats (PNG, JPEG, GIF,...), having to rely on bloated libraries while
       not being able to focus on the task at hand for a given image processing problem.

EXAMPLES

       The  following  code  listing invert.c is a ready-to-use color inverter with all necessary error handling
       and reporting. This program can be integrated into a farbfeld pipeline as follows:

       $ png2ff < image.png | invert | ff2png > image-inverted.png

       It shall be noted here that due to the simplicity of the format  no  external  libraries  are  needed  to
       handle  the  farbfeld  image data. The 0BSD-License gives you the freedom to throw away the license block
       and just use the code as you wish. Happy hacking!

       /*
        * 0BSD-License
        *
        * (c) 2017 Laslo Hunhold <dev@frign.de>
        *
        * Permission to use, copy, modify, and/or distribute this software for
        * any purpose with or without fee is hereby granted.
        *
        * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL
        * WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED
        * WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE
        * AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL
        * DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR
        * PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
        * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
        * PERFORMANCE OF THIS SOFTWARE.
        */
       #include <arpa/inet.h>

       #include <errno.h>
       #include <stdint.h>
       #include <stdio.h>
       #include <string.h>

       #define LEN(x) (sizeof (x) / sizeof *(x))

       static void
       invert(uint16_t rgba[4])
       {
               rgba[0] = UINT16_MAX - rgba[0];
               rgba[1] = UINT16_MAX - rgba[1];
               rgba[2] = UINT16_MAX - rgba[2];
       }

       int
       main(int argc, char *argv[])
       {
               uint32_t hdr[4], width, height, i, j, k;
               uint16_t rgba[4];

               /* arguments */
               if (argc != 1) {
                       fprintf(stderr, "usage: %s\n", argv[0]);
                       return 1;
               }

               /* read header */
               if (fread(hdr, sizeof(*hdr), LEN(hdr), stdin) != LEN(hdr)) {
                       goto readerr;
               }
               if (memcmp("farbfeld", hdr, sizeof("farbfeld") - 1)) {
                       fprintf(stderr, "%s: invalid magic value\n", argv[0]);
                       return 1;
               }
               width = ntohl(hdr[2]);
               height = ntohl(hdr[3]);

               /* write data */
               if (fwrite(hdr, sizeof(*hdr), LEN(hdr), stdout) != 4) {
                       goto writerr;
               }

               for (i = 0; i < height; i++) {
                       for (j = 0; j < width; j++) {
                               if (fread(rgba, sizeof(*rgba), LEN(rgba),
                                         stdin) != LEN(rgba)) {
                                       goto readerr;
                               }
                               for (k = 0; k < 4; k++) {
                                       rgba[k] = ntohs(rgba[k]);
                               }

                               invert(rgba);

                               for (k = 0; k < 4; k++) {
                                       rgba[k] = htons(rgba[k]);
                               }
                               if (fwrite(rgba, sizeof(*rgba), LEN(rgba),
                                          stdout) != LEN(rgba)) {
                                       goto writerr;
                               }
                       }
               }

               /* clean up */
               if (fclose(stdout)) {
                       fprintf(stderr, "%s: fclose: %s\n", argv[0],
                               strerror(errno));
                       return 1;
               }

               return 0;
       readerr:
               fprintf(stderr, "%s: fread: Unexpected EOF\n", argv[0]);
               return 1;
       writerr:
               fprintf(stderr, "%s: fwrite: %s\n", argv[0], strerror(errno));
               return 1;
       }

SEE ALSO

       2ff(1), ff2jpg(1), ff2pam(1), ff2png(1), ff2ppm(1), jpg2ff(1), png2ff(1)

AUTHORS

       Laslo Hunhold <dev@frign.de>

suckless.org                                       2018-04-11                                        FARBFELD(5)