diff --git a/pipi/Makefile.am b/pipi/Makefile.am index 82040fa..b525425 100644 --- a/pipi/Makefile.am +++ b/pipi/Makefile.am @@ -29,6 +29,7 @@ libpipi_la_SOURCES = \ test.c \ $(codec_sources) \ filter/blur.c \ + dither/floydsteinberg.c \ $(NULL) libpipi_la_CFLAGS = $(codec_cflags) libpipi_la_LDFLAGS = $(codec_libs) \ diff --git a/pipi/dither/floydsteinberg.c b/pipi/dither/floydsteinberg.c new file mode 100644 index 0000000..8e50d0b --- /dev/null +++ b/pipi/dither/floydsteinberg.c @@ -0,0 +1,68 @@ +/* + * libpipi Proper image processing implementation library + * Copyright (c) 2004-2008 Sam Hocevar + * All Rights Reserved + * + * $Id$ + * + * This library is free software. It comes without any warranty, to + * the extent permitted by applicable law. You can redistribute it + * and/or modify it under the terms of the Do What The Fuck You Want + * To Public License, Version 2, as published by Sam Hocevar. See + * http://sam.zoy.org/wtfpl/COPYING for more details. + */ + +/* + * floydsteinberg.c: Floyd-Steinberg dithering functions + */ + +#include "config.h" +#include "common.h" + +#include "pipi.h" +#include "pipi_internals.h" + +pipi_image_t *pipi_floydsteinberg(pipi_image_t *src) +{ + pipi_image_t *dst; + pipi_pixels_t *srcp, *dstp; + float *srcdata, *dstdata; + int x, y, w, h; + + w = src->w; + h = src->h; + + srcp = pipi_getpixels(src, PIPI_PIXELS_Y_F); + srcdata = (float *)srcp->pixels; + + dst = pipi_new(w, h); + dstp = pipi_getpixels(dst, PIPI_PIXELS_Y_F); + dstdata = (float *)dstp->pixels; + + for(y = 0; y < h; y++) + { + for(x = 0; x < w; x++) + { + float p, q, e; + + p = srcdata[y * w + x]; + q = p < 0.5 ? 0. : 1.; + dstdata[y * w + x] = q; + + e = p - q; + if(x < w - 1) + srcdata[y * w + x + 1] += e * .4375; + if(y < h - 1) + { + if(x > 0) + srcdata[(y + 1) * w + x - 1] += e * .1875; + srcdata[(y + 1) * w + x] += e * .3125; + if(x < w - 1) + srcdata[(y + 1) * w + x + 1] += e * .0625; + } + } + } + + return dst; +} + diff --git a/pipi/pipi.h b/pipi/pipi.h index 67a33ea..6642569 100644 --- a/pipi/pipi.h +++ b/pipi/pipi.h @@ -67,6 +67,7 @@ extern pipi_image_t *pipi_gaussian_blur(pipi_image_t *, float); extern pipi_image_t *pipi_gaussian_blur_ext(pipi_image_t *, float, float, float, float); +extern pipi_image_t *pipi_floydsteinberg(pipi_image_t *); extern void pipi_dither_24to16(pipi_image_t *); extern void pipi_test(pipi_image_t *);