[FFmpeg-devel] [PATCH] lavfi: add histeq filter (WIP)
Jérémy Tran
tran.jeremy.av at gmail.com
Mon Oct 15 05:41:11 CEST 2012
This is a port of virtual dub's histogram equalization filter by
Donald A. Graft.
I reworked stefano's previous port (that used YUV colorspace) to use RGB
colorspace like the original filter but the output is not correct yet.
I am posting this patch to get a fist review, maybe there's something that
I obviously got wrong.
Thanks.
---
configure | 1 +
doc/filters.texi | 43 ++++++++
libavfilter/Makefile | 1 +
libavfilter/allfilters.c | 1 +
libavfilter/vf_histeq.c | 282 +++++++++++++++++++++++++++++++++++++++++++++++
5 files changed, 328 insertions(+)
create mode 100644 libavfilter/vf_histeq.c
diff --git a/configure b/configure
index 5aa891b..a72987c 100755
--- a/configure
+++ b/configure
@@ -1916,6 +1916,7 @@ frei0r_filter_deps="frei0r dlopen"
frei0r_filter_extralibs='$ldl'
frei0r_src_filter_deps="frei0r dlopen"
frei0r_src_filter_extralibs='$ldl'
+histeq_filter_deps="gpl"
hqdn3d_filter_deps="gpl"
movie_filter_deps="avcodec avformat"
mp_filter_deps="gpl avcodec swscale postproc inline_asm"
diff --git a/doc/filters.texi b/doc/filters.texi
index 725c7b5..6bb293e 100644
--- a/doc/filters.texi
+++ b/doc/filters.texi
@@ -2285,6 +2285,49 @@ For example to horizontally flip the input video with @command{ffmpeg}:
ffmpeg -i in.avi -vf "hflip" out.avi
@end example
+ at section histeq
+From the original author's description:
+This filter applies a global color histogram equalization on a per-frame basis.
+It can be used to correct video that has a compressed range of pixel intensities.
+The filter redistributes the pixel intensities to equalize their distribution
+across the intensity range. It may be viewed as an "automatically adjusting
+contrast filter". This filter is useful only for correcting degraded or poorly
+captured source video. It should not be applied willy-nilly, as it leads to a
+modification of image content.
+
+The filter takes these optional parameters separated by ':':
+ at var{strength}:@var{intensity}:@var{antibanding}
+
+ at var{strength} must be an integer and determines the amount of equalization to
+be applied. As the strength is reduced, the distribution of pixel intensities
+more-and-more approaches that of the input frame.
+It defaults to 200.
+
+ at var{intensity} must be an integer and sets the maximum intensity that can
+generated and scales the output values appropriately. The strength should be
+set as desired and then the intensity can be limited if needed to avoid
+washing-out.
+It defaults to 210.
+
+ at var{antibanding} must be 'none', 'weak' or 'strong' and randomly varies the
+luminance of output pixels by a small amount to avoid banding of the histogram.
+It defaults to 'none'.
+
+Some examples follow:
+ at itemize
+ at item
+Use default values
+ at example
+histeq
+ at end example
+
+ at item
+Use defaults strength and intensity values and enable strong antibanding
+ at example
+histeq=200:210:strong
+ at end example
+ at end itemize
+
@section hqdn3d
High precision/quality 3d denoise filter. This filter aims to reduce
diff --git a/libavfilter/Makefile b/libavfilter/Makefile
index 3618f10..bf82266 100644
--- a/libavfilter/Makefile
+++ b/libavfilter/Makefile
@@ -106,6 +106,7 @@ OBJS-$(CONFIG_FPS_FILTER) += vf_fps.o
OBJS-$(CONFIG_FREI0R_FILTER) += vf_frei0r.o
OBJS-$(CONFIG_GRADFUN_FILTER) += vf_gradfun.o
OBJS-$(CONFIG_HFLIP_FILTER) += vf_hflip.o
+OBJS-$(CONFIG_HISTEQ_FILTER) += vf_histeq.o
OBJS-$(CONFIG_HQDN3D_FILTER) += vf_hqdn3d.o
OBJS-$(CONFIG_HUE_FILTER) += vf_hue.o
OBJS-$(CONFIG_IDET_FILTER) += vf_idet.o
diff --git a/libavfilter/allfilters.c b/libavfilter/allfilters.c
index 348f369..2d7c95f 100644
--- a/libavfilter/allfilters.c
+++ b/libavfilter/allfilters.c
@@ -98,6 +98,7 @@ void avfilter_register_all(void)
REGISTER_FILTER (FREI0R, frei0r, vf);
REGISTER_FILTER (GRADFUN, gradfun, vf);
REGISTER_FILTER (HFLIP, hflip, vf);
+ REGISTER_FILTER (HISTEQ, histeq, vf);
REGISTER_FILTER (HQDN3D, hqdn3d, vf);
REGISTER_FILTER (HUE, hue, vf);
REGISTER_FILTER (IDET, idet, vf);
diff --git a/libavfilter/vf_histeq.c b/libavfilter/vf_histeq.c
new file mode 100644
index 0000000..5eeeb3b
--- /dev/null
+++ b/libavfilter/vf_histeq.c
@@ -0,0 +1,282 @@
+/*
+ * Copyright (c) 2010 Stefano Sabatini
+ * Copyright (c) 2001 Donald A. Graft
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+/**
+ * @file
+ * Histogram equalization filter, based on the VirtualDub filter by
+ * Donald A. Graft <neuron2 AT home DOT com>.
+ * Implements global automatic contrast adjustment by means of
+ * histogram equalization.
+ */
+
+/* #define DEBUG */
+
+#include "libavutil/common.h"
+#include "libavutil/pixdesc.h"
+
+#include "avfilter.h"
+#include "formats.h"
+#include "video.h"
+
+#define NONE 0
+#define WEAK 1
+#define STRONG 2
+
+#define R 0
+#define G 1
+#define B 2
+#define A 3
+
+typedef struct {
+ int strength;
+ int intensity;
+ int antibanding;
+ int in_histogram [256]; ///< input histogram
+ int out_histogram[256]; ///< output histogram
+ int LUT[256]; ///< lookup table derived from histogram[]
+ unsigned int jran, ia, ic, im;
+ int vsub, hsub;
+ int rgba_map[4]; ///< components position
+ int bpp; ///< bytes per pixel
+} HisteqContext;
+
+static av_cold int init(AVFilterContext *ctx, const char *args)
+{
+ HisteqContext *histeq = ctx->priv;
+ char antibanding_str[128] = "none";
+
+ histeq->strength = 200;
+ histeq->intensity = 210;
+ histeq->ia = 4096;
+ histeq->ic = 150889;
+ histeq->im = 714025;
+
+ if (args)
+ sscanf(args, "%d:%d:%s", &histeq->strength, &histeq->intensity, antibanding_str);
+
+ if (!strcmp(antibanding_str, "none" )) histeq->antibanding = NONE;
+ else if (!strcmp(antibanding_str, "weak" )) histeq->antibanding = WEAK;
+ else if (!strcmp(antibanding_str, "strong")) histeq->antibanding = STRONG;
+ else {
+ av_log(ctx, AV_LOG_ERROR, "Unknown value for antibanding '%s'.\n", antibanding_str);
+ return AVERROR(EINVAL);
+ }
+
+ av_log(ctx, AV_LOG_INFO, "strength:%d intensity:%d antibanding:%s\n",
+ histeq->strength, histeq->intensity, antibanding_str);
+
+ return 0;
+}
+
+static int query_formats(AVFilterContext *ctx)
+{
+ static const enum PixelFormat pix_fmts[] = {
+ PIX_FMT_ARGB, PIX_FMT_RGBA,
+ PIX_FMT_ABGR, PIX_FMT_BGRA,
+ PIX_FMT_NONE
+ };
+
+ ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+
+ return 0;
+}
+
+static int config_input(AVFilterLink *inlink)
+{
+ AVFilterContext *ctx = inlink->dst;
+ HisteqContext *histeq = ctx->priv;
+ const AVPixFmtDescriptor *pix_desc = &av_pix_fmt_descriptors[inlink->format];
+
+ histeq->hsub = pix_desc->log2_chroma_w;
+ histeq->vsub = pix_desc->log2_chroma_h;
+ histeq->bpp = av_get_bits_per_pixel(pix_desc) / 8;
+
+ switch (inlink->format) {
+ case PIX_FMT_ARGB:
+ histeq->rgba_map[R] = 2;
+ histeq->rgba_map[G] = 1;
+ histeq->rgba_map[B] = 0;
+ histeq->rgba_map[A] = 3;
+ break;
+ case PIX_FMT_RGBA:
+ histeq->rgba_map[R] = 3;
+ histeq->rgba_map[G] = 2;
+ histeq->rgba_map[B] = 1;
+ histeq->rgba_map[A] = 0;
+ break;
+ case PIX_FMT_ABGR:
+ histeq->rgba_map[R] = 0;
+ histeq->rgba_map[G] = 1;
+ histeq->rgba_map[B] = 2;
+ histeq->rgba_map[A] = 3;
+ break;
+ case PIX_FMT_BGRA:
+ histeq->rgba_map[R] = 1;
+ histeq->rgba_map[G] = 2;
+ histeq->rgba_map[B] = 3;
+ histeq->rgba_map[A] = 0;
+ break;
+ default:
+ break;
+ }
+
+ return 0;
+}
+
+#define COMPUTE_RGB_VALUES(r, g, b, src, map) do { \
+ r = src[x + map[R]]; \
+ g = src[x + map[G]]; \
+ b = src[x + map[B]]; \
+} while (0)
+
+static int end_frame(AVFilterLink *inlink)
+{
+ AVFilterContext *ctx = inlink->dst;
+ HisteqContext *histeq = ctx->priv;
+ AVFilterBufferRef *inpic = inlink->cur_buf;
+ AVFilterLink *outlink = ctx->outputs[0];
+ AVFilterBufferRef *outpic = outlink->out_buf;
+ int x, y, i, luthi, lutlo, lut, luma, oluma, m;
+ unsigned int r, g, b;
+ uint8_t *src, *dst;
+
+ /* Seed random generator for antibanding. */
+ histeq->jran = 739187UL;
+
+ /* Calculate and store the luminance and calculate the global histogram
+ based on the luminance. */
+ memset(histeq->in_histogram, 0, sizeof(histeq->in_histogram));
+ src = inpic->data[0];
+ dst = outpic->data[0];
+ for (y = 0; y < inlink->h; y++) {
+ for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
+ COMPUTE_RGB_VALUES(r, g, b, src, histeq->rgba_map);
+ luma = (55 * r + 182 * g + 19 * b) >> 8;
+ dst[x + histeq->rgba_map[A]] = luma;
+ histeq->in_histogram[luma]++;
+ }
+ src += inpic->linesize[0];
+ dst += outpic->linesize[0];
+ }
+#ifdef DEBUG
+ for (x = 0; x < 256; x++)
+ av_log(ctx, AV_LOG_DEBUG, "in[%d]: %u\n", x, histeq->in_histogram[x]);
+#endif
+
+ /* Calculate the lookup table. */
+ histeq->LUT[0] = histeq->in_histogram[0];
+ /* Accumulate */
+ for (x = 1; x < 256; x++)
+ histeq->LUT[x] = histeq->LUT[x-1] + histeq->in_histogram[x];
+
+ /* Normalize. */
+ for (x = 0; x < 256; x++)
+ histeq->LUT[x] = (histeq->LUT[x] * histeq->intensity) / (inlink->h * inlink->w);
+
+ /* Adjust the LUT based on the selected strength. This is an alpha
+ mix of the calculated LUT and a linear LUT with gain 1. */
+ for (x = 0; x < 256; x++)
+ histeq->LUT[x] = (histeq->strength * histeq->LUT[x]) / 255 +
+ ((255 - histeq->strength) * x) / 255;
+
+ /* Output the equalized frame. */
+ memset(histeq->out_histogram, 0, sizeof(histeq->out_histogram));
+
+ src = inpic->data[0];
+ dst = outpic->data[0];
+ for (y = 0; y < inlink->h; y++) {
+ for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
+ luma = dst[x + histeq->rgba_map[A]];
+ if (luma == 0) {
+ for (i = 0; i < histeq->bpp; ++i)
+ dst[x + i] = 0;
+ histeq->out_histogram[0]++;
+ } else {
+ lut = histeq->LUT[luma];
+ if (histeq->antibanding != NONE) {
+ if (luma > 0) {
+ lutlo = histeq->antibanding == WEAK ?
+ (histeq->LUT[luma] + histeq->LUT[luma - 1]) / 2 :
+ histeq->LUT[luma - 1];
+ } else
+ lutlo = lut;
+
+ if (luma < 255) {
+ luthi = (histeq->antibanding == WEAK) ?
+ (histeq->LUT[luma] + histeq->LUT[luma + 1]) / 2 :
+ histeq->LUT[luma + 1];
+ } else
+ luthi = lut;
+
+ if (lutlo != luthi) {
+ histeq->jran = (histeq->jran * histeq->ia + histeq->ic) % histeq->im;
+ lut = lutlo + ((luthi - lutlo + 1) * histeq->jran) / histeq->im;
+ }
+ }
+
+ COMPUTE_RGB_VALUES(r, g, b, src, histeq->rgba_map);
+ if (((m = FFMAX(r, FFMAX(g, b))) * lut) / luma > 255) {
+ r = (r * 255) / m;
+ g = (g * 255) / m;
+ b = (b * 255) / m;
+ } else {
+ r = (r * lut) / luma;
+ g = (g * lut) / luma;
+ b = (b * lut) / luma;
+ }
+ dst[x + histeq->rgba_map[R]] = r;
+ dst[x + histeq->rgba_map[G]] = g;
+ dst[x + histeq->rgba_map[B]] = b;
+ oluma = (55 * r + 182 * g + 19 * b) >> 8;
+ histeq->out_histogram[oluma]++;
+ }
+ }
+ src += inpic->linesize[0];
+ dst += outpic->linesize[0];
+ }
+#ifdef DEBUG
+ for (x = 0; x < 256; x++)
+ av_log(ctx, AV_LOG_DEBUG, "out[%d]: %u\n", x, histeq->out_histogram[x]);
+#endif
+
+ return ff_end_frame(outlink);
+}
+
+AVFilter avfilter_vf_histeq = {
+ .name = "histeq",
+ .description = NULL_IF_CONFIG_SMALL("Perform global color histogram equalization."),
+
+ .priv_size = sizeof(HisteqContext),
+ .init = init,
+ .query_formats = query_formats,
+
+ .inputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO,
+ .config_props = config_input,
+ .end_frame = end_frame,
+ .min_perms = AV_PERM_WRITE | AV_PERM_READ,
+ .rej_perms = AV_PERM_PRESERVE },
+ { .name = NULL}},
+
+ .outputs = (AVFilterPad[]) {{ .name = "default",
+ .type = AVMEDIA_TYPE_VIDEO, },
+ { .name = NULL}},
+};
--
1.7.11.3
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