.Dd 2016-01-04
.Dt FARBFELD 5
.Os suckless.org
.Sh NAME
.Nm farbfeld
.Nd suckless image format
.Sh DESCRIPTION
.Nm
is a
.Em lossless
image format which is easy to parse, pipe and compress.
It has the following format:
.Bd -literal -offset left
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
.Ed
The RGB-data should be sRGB for best interoperability and not
alpha-premultiplied.
.Sh USAGE
.Nm
provides
.Xr png2ff 1 ,
.Xr jpg2ff 1 ,
.Xr 2ff 1 ,
.Xr ff2png 1
for
.Em conversions ;
.Xr bzip2 1
is recommended for
.Em compression ,
giving results comparable with PNG for photographs and much better results
for other image types.
.sp
The
.Em file extension
is ".ff" and compression extensions shall be
appended (e.g. ".ff.bz2").
.Sh MOTIVATION
.Nm
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 not being able
to focus on the task at hand for a given problem.
.Sh EXAMPLES
Below is an example for a color inverter usable in a pipeline. No external
libraries other than libc are needed to handle the image data:
.Bd -literal -offset left
#include <arpa/inet.h>

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

int
main(int argc, char *argv[])
{
	uint32_t width, height, i, j, k;
	uint16_t rgba[4];
	uint8_t hdr[strlen("farbfeld") + 2 * sizeof(uint32_t)];

	if (argc > 1) {
		fprintf(stderr, "usage: %s\\n", argv[0]);
		return 1;
	}

	if (fread(hdr, 1, sizeof(hdr), stdin) != sizeof(hdr)) {
		fprintf(stderr, "incomplete header\\n");
		return 1;
	}
	if (memcmp("farbfeld", hdr, strlen("farbfeld"))) {
		fprintf(stderr, "invalid magic\\n");
		return 1;
	}
	width = ntohl(*((uint32_t *)(hdr + 8)));
	height = ntohl(*((uint32_t *)(hdr + 12)));

	if (fwrite(hdr, 1, sizeof(hdr), stdout) != sizeof(hdr)) {
		fprintf(stderr, "write error\\n");
		return 1;
	}

	for (i = 0; i < height; i++) {
		for (j = 0; j < width; j++) {
			if (fread(rgba, sizeof(uint16_t), 4,
			          stdin) != 4) {
				fprintf(stderr, "unexpected EOF\\n");
				return 1;
			}
			for (k = 0; k < 4; k++) {
				rgba[k] = ntohs(rgba[k]);
			}

			/* invert colors */
			rgba[0] = 65535 - rgba[0];
			rgba[1] = 65535 - rgba[1];
			rgba[2] = 65535 - rgba[2];

			for (k = 0; k < 4; k++) {
				rgba[k] = htons(rgba[k]);
			}
			if (fwrite(rgba, sizeof(uint16_t), 4,
			           stdout) != 4) {
				fprintf(stderr, "write error\\n");
				return 1;
			}
		}
	}

	return 0;
}
.Ed
.Sh SEE ALSO
.Xr 2ff 1 ,
.Xr bzip2 1 ,
.Xr ff2png 1 ,
.Xr jpg2ff 1 ,
.Xr png2ff 1
.Sh AUTHORS
.An Laslo Hunhold Aq Mt dev@frign.de