[FFmpeg-devel] [PATCH] lavfi: add histeq filter (WIP)
Stefano Sabatini
stefasab at gmail.com
Mon Oct 15 12:40:32 CEST 2012
On date Monday 2012-10-15 05:41:11 +0200, Jérémy Tran encoded:
> 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.
In which sense is "not correct"? That may help to spot the issue.
> 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:
Skip this sentence, since we may want to reword/rephrase it, breaking
the quote.
> +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 ':':
av_opt_set_from_string() and named options, now that we have this luxury.
> + 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.
This doesn't tell the range of the value. I wonder if we should rather
adopt a more generic scale (float value in the range 0-1).
> +
> + 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
Add your name here, feel free to discard mine if you did enough
changes to my original port (so we avoid another copyright soup).
> + *
> + * 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.
> + */
Note, did you try to contact the author about the licensing? IIRC I
tried during the port, and I failed to get a reply.
> +
> +/* #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;
doxy
> + 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;
magic?
> +
> + if (args)
> + sscanf(args, "%d:%d:%s", &histeq->strength, &histeq->intensity, antibanding_str);
av_opt_set_from_string()
> +
> + 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));
Note: we should make this return a ret value.
> +
> + 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;
> +}
libavfilter/drawutils.h:ff_fill_rgba_map
> +
> +#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",
const AVFilterPad
> + .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",
const AVFilterPad
--
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