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>