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Diffstat (limited to 'libavfilter/vf_histeq.c')
| -rw-r--r-- | libavfilter/vf_histeq.c | 281 |
1 files changed, 281 insertions, 0 deletions
diff --git a/libavfilter/vf_histeq.c b/libavfilter/vf_histeq.c new file mode 100644 index 0000000000..6fdb7be231 --- /dev/null +++ b/libavfilter/vf_histeq.c @@ -0,0 +1,281 @@ +/* + * Copyright (c) 2012 Jeremy Tran + * 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. + */ + +#include "libavutil/common.h" +#include "libavutil/opt.h" +#include "libavutil/pixdesc.h" + +#include "avfilter.h" +#include "drawutils.h" +#include "formats.h" +#include "internal.h" +#include "video.h" + +// #define DEBUG + +// Linear Congruential Generator, see "Numerical Recipes" +#define LCG_A 4096 +#define LCG_C 150889 +#define LCG_M 714025 +#define LCG(x) (((x) * LCG_A + LCG_C) % LCG_M) +#define LCG_SEED 739187 + +enum HisteqAntibanding { + HISTEQ_ANTIBANDING_NONE = 0, + HISTEQ_ANTIBANDING_WEAK = 1, + HISTEQ_ANTIBANDING_STRONG = 2, + HISTEQ_ANTIBANDING_NB, +}; + +typedef struct { + const AVClass *class; + float strength; + float intensity; + enum HisteqAntibanding antibanding; + int in_histogram [256]; ///< input histogram + int out_histogram[256]; ///< output histogram + int LUT[256]; ///< lookup table derived from histogram[] + uint8_t rgba_map[4]; ///< components position + int bpp; ///< bytes per pixel +} HisteqContext; + +#define OFFSET(x) offsetof(HisteqContext, x) +#define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM +#define CONST(name, help, val, unit) { name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit } + +static const AVOption histeq_options[] = { + { "strength", "set the strength", OFFSET(strength), AV_OPT_TYPE_FLOAT, {.dbl=0.2}, 0, 1, FLAGS }, + { "intensity", "set the intensity", OFFSET(intensity), AV_OPT_TYPE_FLOAT, {.dbl=0.21}, 0, 1, FLAGS }, + { "antibanding", "set the antibanding level", OFFSET(antibanding), AV_OPT_TYPE_INT, {.i64=HISTEQ_ANTIBANDING_NONE}, 0, HISTEQ_ANTIBANDING_NB-1, FLAGS, "antibanding" }, + CONST("none", "apply no antibanding", HISTEQ_ANTIBANDING_NONE, "antibanding"), + CONST("weak", "apply weak antibanding", HISTEQ_ANTIBANDING_WEAK, "antibanding"), + CONST("strong", "apply strong antibanding", HISTEQ_ANTIBANDING_STRONG, "antibanding"), + { NULL } +}; + +AVFILTER_DEFINE_CLASS(histeq); + +static av_cold int init(AVFilterContext *ctx) +{ + HisteqContext *histeq = ctx->priv; + + av_log(ctx, AV_LOG_VERBOSE, + "strength:%0.3f intensity:%0.3f antibanding:%d\n", + histeq->strength, histeq->intensity, histeq->antibanding); + + return 0; +} + +static int query_formats(AVFilterContext *ctx) +{ + static const enum PixelFormat pix_fmts[] = { + AV_PIX_FMT_ARGB, AV_PIX_FMT_RGBA, AV_PIX_FMT_ABGR, AV_PIX_FMT_BGRA, + AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24, + AV_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_desc_get(inlink->format); + + histeq->bpp = av_get_bits_per_pixel(pix_desc) / 8; + ff_fill_rgba_map(histeq->rgba_map, inlink->format); + + return 0; +} + +#define R 0 +#define G 1 +#define B 2 +#define A 3 + +#define GET_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 filter_frame(AVFilterLink *inlink, AVFrame *inpic) +{ + AVFilterContext *ctx = inlink->dst; + HisteqContext *histeq = ctx->priv; + AVFilterLink *outlink = ctx->outputs[0]; + int strength = histeq->strength * 1000; + int intensity = histeq->intensity * 1000; + int x, y, i, luthi, lutlo, lut, luma, oluma, m; + AVFrame *outpic; + unsigned int r, g, b, jran; + uint8_t *src, *dst; + + outpic = ff_get_video_buffer(outlink, outlink->w, outlink->h); + if (!outpic) { + av_frame_free(&inpic); + return AVERROR(ENOMEM); + } + av_frame_copy_props(outpic, inpic); + + /* Seed random generator for antibanding. */ + jran = LCG_SEED; + + /* 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) { + GET_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_dlog(ctx, "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] * 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] = (strength * histeq->LUT[x]) / 255 + + ((255 - 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 != HISTEQ_ANTIBANDING_NONE) { + if (luma > 0) { + lutlo = histeq->antibanding == HISTEQ_ANTIBANDING_WEAK ? + (histeq->LUT[luma] + histeq->LUT[luma - 1]) / 2 : + histeq->LUT[luma - 1]; + } else + lutlo = lut; + + if (luma < 255) { + luthi = (histeq->antibanding == HISTEQ_ANTIBANDING_WEAK) ? + (histeq->LUT[luma] + histeq->LUT[luma + 1]) / 2 : + histeq->LUT[luma + 1]; + } else + luthi = lut; + + if (lutlo != luthi) { + jran = LCG(jran); + lut = lutlo + ((luthi - lutlo + 1) * jran) / LCG_M; + } + } + + GET_RGB_VALUES(r, g, b, src, histeq->rgba_map); + if (((m = FFMAX3(r, 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 = av_clip_uint8((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_dlog(ctx, "out[%d]: %u\n", x, histeq->out_histogram[x]); +#endif + + av_frame_free(&inpic); + return ff_filter_frame(outlink, outpic); +} + +static const AVFilterPad histeq_inputs[] = { + { + .name = "default", + .type = AVMEDIA_TYPE_VIDEO, + .config_props = config_input, + .filter_frame = filter_frame, + }, + { NULL } +}; + +static const AVFilterPad histeq_outputs[] = { + { + .name = "default", + .type = AVMEDIA_TYPE_VIDEO, + }, + { NULL } +}; + +AVFilter ff_vf_histeq = { + .name = "histeq", + .description = NULL_IF_CONFIG_SMALL("Apply global color histogram equalization."), + .priv_size = sizeof(HisteqContext), + .init = init, + .query_formats = query_formats, + .inputs = histeq_inputs, + .outputs = histeq_outputs, + .priv_class = &histeq_class, + .flags = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC, +}; |