From 25cdf35a86d413e52c9d578d1e006bc854acee93 Mon Sep 17 00:00:00 2001
From: sam <sam@92316355-f0b4-4df1-b90c-862c8a59935f>
Date: Mon, 11 Aug 2008 20:02:34 +0000
Subject: [PATCH] * jajuni.c: add Jarvis-Judice-Ninke dithering. It's a
Floyd-Steinberg-like error diffusion method that has fewer high
resolution structural artifacts at the expense of resolution.
git-svn-id: file:///srv/caca.zoy.org/var/lib/svn/libpipi/trunk@2700 92316355-f0b4-4df1-b90c-862c8a59935f
---
pipi/Makefile.am | 1 +
pipi/context.c | 4 ++
pipi/dither/jajuni.c | 87 ++++++++++++++++++++++++++++++++++++++++++++
pipi/pipi.h | 1 +
4 files changed, 93 insertions(+)
create mode 100644 pipi/dither/jajuni.c
diff --git a/pipi/Makefile.am b/pipi/Makefile.am
index 5051d02..8c9a0dc 100644
--- a/pipi/Makefile.am
+++ b/pipi/Makefile.am
@@ -45,6 +45,7 @@ filter_sources = \
dither_sources = \
dither/floydsteinberg.c \
+ dither/jajuni.c \
dither/ordered.c \
dither/ostromoukhov.c \
dither/dbs.c \
diff --git a/pipi/context.c b/pipi/context.c
index 0c0f6d9..ccfdd18 100644
--- a/pipi/context.c
+++ b/pipi/context.c
@@ -88,6 +88,10 @@ int pipi_command(pipi_context_t *ctx, char const *cmd, ...)
dst = pipi_dither_floydsteinberg(src, 0);
else if(!strcmp(method, "sfs"))
dst = pipi_dither_floydsteinberg(src, 1);
+ else if(!strcmp(method, "jajuni"))
+ dst = pipi_dither_jajuni(src, 0);
+ else if(!strcmp(method, "sjajuni"))
+ dst = pipi_dither_jajuni(src, 1);
else if(!strcmp(method, "ost"))
dst = pipi_dither_ostromoukhov(src, 0);
else if(!strcmp(method, "sost"))
diff --git a/pipi/dither/jajuni.c b/pipi/dither/jajuni.c
new file mode 100644
index 0000000..45f9aa0
--- /dev/null
+++ b/pipi/dither/jajuni.c
@@ -0,0 +1,87 @@
+/*
+ * libpipi Proper image processing implementation library
+ * Copyright (c) 2004-2008 Sam Hocevar <sam@zoy.org>
+ * 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.
+ */
+
+/*
+ * jajuni.c: Jarvis-Judice-Ninke dithering functions
+ */
+
+#include "config.h"
+#include "common.h"
+
+#include "pipi.h"
+#include "pipi_internals.h"
+
+pipi_image_t *pipi_dither_jajuni(pipi_image_t *img, pipi_scan_t scan)
+{
+ pipi_image_t *dst;
+ pipi_pixels_t *dstp;
+ float *dstdata;
+ int x, y, w, h;
+
+ w = img->w;
+ h = img->h;
+
+ dst = pipi_copy(img);
+ dstp = pipi_getpixels(dst, PIPI_PIXELS_Y_F);
+ dstdata = (float *)dstp->pixels;
+
+ for(y = 0; y < h; y++)
+ {
+ int reverse = (y & 1) && (scan == PIPI_SCAN_SERPENTINE);
+
+ for(x = 0; x < w; x++)
+ {
+ float p, q, e;
+ int x2 = reverse ? w - 1 - x : x;
+ int s = reverse ? -1 : 1;
+
+ p = dstdata[y * w + x2];
+ q = p < 0.5 ? 0. : 1.;
+ dstdata[y * w + x2] = q;
+
+ e = (p - q) / 48.;
+ if(x < w - 1)
+ dstdata[y * w + x2 + s] += e * 7;
+ if(x < w - 2)
+ dstdata[y * w + x2 + s + s] += e * 5;
+ if(y < h - 1)
+ {
+ if(x > 1)
+ dstdata[(y + 1) * w + x2 - s - s] += e * 3;
+ if(x > 0)
+ dstdata[(y + 1) * w + x2 - s] += e * 5;
+ dstdata[(y + 1) * w + x2] += e * 7;
+ if(x < w - 1)
+ dstdata[(y + 1) * w + x2 + s] += e * 5;
+ if(x < w - 2)
+ dstdata[(y + 1) * w + x2 + s + s] += e * 3;
+ }
+ if(y < h - 2)
+ {
+ if(x > 1)
+ dstdata[(y + 2) * w + x2 - s - s] += e;
+ if(x > 0)
+ dstdata[(y + 2) * w + x2 - s] += e * 3;
+ dstdata[(y + 2) * w + x2] += e * 5;
+ if(x < w - 1)
+ dstdata[(y + 2) * w + x2 + s] += e * 3;
+ if(x < w - 2)
+ dstdata[(y + 2) * w + x2 + s + s] += e;
+ }
+ }
+ }
+
+ return dst;
+}
+
diff --git a/pipi/pipi.h b/pipi/pipi.h
index 3d74c52..0c734b9 100644
--- a/pipi/pipi.h
+++ b/pipi/pipi.h
@@ -97,6 +97,7 @@ extern int pipi_flood_fill(pipi_image_t *,
int, int, float, float, float, float);
extern pipi_image_t *pipi_dither_floydsteinberg(pipi_image_t *, pipi_scan_t);
+extern pipi_image_t *pipi_dither_jajuni(pipi_image_t *, pipi_scan_t);
extern pipi_image_t *pipi_dither_ordered(pipi_image_t *, pipi_image_t *);
extern pipi_image_t *pipi_dither_random(pipi_image_t *);
extern pipi_image_t *pipi_dither_ostromoukhov(pipi_image_t *, pipi_scan_t);