yading@10: /*
yading@10:  * Copyright (c) 2012 Jeremy Tran
yading@10:  * Copyright (c) 2001 Donald A. Graft
yading@10:  *
yading@10:  * This file is part of FFmpeg.
yading@10:  *
yading@10:  * FFmpeg is free software; you can redistribute it and/or modify
yading@10:  * it under the terms of the GNU General Public License as published by
yading@10:  * the Free Software Foundation; either version 2 of the License, or
yading@10:  * (at your option) any later version.
yading@10:  *
yading@10:  * FFmpeg is distributed in the hope that it will be useful,
yading@10:  * but WITHOUT ANY WARRANTY; without even the implied warranty of
yading@10:  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
yading@10:  * GNU General Public License for more details.
yading@10:  *
yading@10:  * You should have received a copy of the GNU General Public License along
yading@10:  * with FFmpeg; if not, write to the Free Software Foundation, Inc.,
yading@10:  * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
yading@10:  */
yading@10: 
yading@10: /**
yading@10:  * @file
yading@10:  * Histogram equalization filter, based on the VirtualDub filter by
yading@10:  * Donald A. Graft  <neuron2 AT home DOT com>.
yading@10:  * Implements global automatic contrast adjustment by means of
yading@10:  * histogram equalization.
yading@10:  */
yading@10: 
yading@10: #include "libavutil/common.h"
yading@10: #include "libavutil/opt.h"
yading@10: #include "libavutil/pixdesc.h"
yading@10: 
yading@10: #include "avfilter.h"
yading@10: #include "drawutils.h"
yading@10: #include "formats.h"
yading@10: #include "internal.h"
yading@10: #include "video.h"
yading@10: 
yading@10: // #define DEBUG
yading@10: 
yading@10: // Linear Congruential Generator, see "Numerical Recipes"
yading@10: #define LCG_A 4096
yading@10: #define LCG_C 150889
yading@10: #define LCG_M 714025
yading@10: #define LCG(x) (((x) * LCG_A + LCG_C) % LCG_M)
yading@10: #define LCG_SEED 739187
yading@10: 
yading@10: enum HisteqAntibanding {
yading@10:     HISTEQ_ANTIBANDING_NONE   = 0,
yading@10:     HISTEQ_ANTIBANDING_WEAK   = 1,
yading@10:     HISTEQ_ANTIBANDING_STRONG = 2,
yading@10:     HISTEQ_ANTIBANDING_NB,
yading@10: };
yading@10: 
yading@10: typedef struct {
yading@10:     const AVClass *class;
yading@10:     float strength;
yading@10:     float intensity;
yading@10:     enum HisteqAntibanding antibanding;
yading@10:     char* antibanding_str;
yading@10:     int in_histogram [256];        ///< input histogram
yading@10:     int out_histogram[256];        ///< output histogram
yading@10:     int LUT[256];                  ///< lookup table derived from histogram[]
yading@10:     uint8_t rgba_map[4];           ///< components position
yading@10:     int bpp;                       ///< bytes per pixel
yading@10: } HisteqContext;
yading@10: 
yading@10: #define OFFSET(x) offsetof(HisteqContext, x)
yading@10: #define FLAGS AV_OPT_FLAG_VIDEO_PARAM|AV_OPT_FLAG_FILTERING_PARAM
yading@10: #define CONST(name, help, val, unit) { name, help, 0, AV_OPT_TYPE_CONST, {.i64=val}, INT_MIN, INT_MAX, FLAGS, unit }
yading@10: 
yading@10: static const AVOption histeq_options[] = {
yading@10:     { "strength",    "set the strength", OFFSET(strength), AV_OPT_TYPE_FLOAT, {.dbl=0.2}, 0, 1, FLAGS },
yading@10:     { "intensity",   "set the intensity", OFFSET(intensity), AV_OPT_TYPE_FLOAT, {.dbl=0.21}, 0, 1, FLAGS },
yading@10:     { "antibanding", "set the antibanding level", OFFSET(antibanding), AV_OPT_TYPE_INT, {.i64=HISTEQ_ANTIBANDING_NONE}, 0, HISTEQ_ANTIBANDING_NB-1, FLAGS, "antibanding" },
yading@10:     CONST("none",    "apply no antibanding",     HISTEQ_ANTIBANDING_NONE,   "antibanding"),
yading@10:     CONST("weak",    "apply weak antibanding",   HISTEQ_ANTIBANDING_WEAK,   "antibanding"),
yading@10:     CONST("strong",  "apply strong antibanding", HISTEQ_ANTIBANDING_STRONG, "antibanding"),
yading@10:     { NULL }
yading@10: };
yading@10: 
yading@10: AVFILTER_DEFINE_CLASS(histeq);
yading@10: 
yading@10: static av_cold int init(AVFilterContext *ctx)
yading@10: {
yading@10:     HisteqContext *histeq = ctx->priv;
yading@10: 
yading@10:     av_log(ctx, AV_LOG_VERBOSE,
yading@10:            "strength:%0.3f intensity:%0.3f antibanding:%d\n",
yading@10:            histeq->strength, histeq->intensity, histeq->antibanding);
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int query_formats(AVFilterContext *ctx)
yading@10: {
yading@10:     static const enum PixelFormat pix_fmts[] = {
yading@10:         AV_PIX_FMT_ARGB, AV_PIX_FMT_RGBA, AV_PIX_FMT_ABGR, AV_PIX_FMT_BGRA,
yading@10:         AV_PIX_FMT_RGB24, AV_PIX_FMT_BGR24,
yading@10:         AV_PIX_FMT_NONE
yading@10:     };
yading@10: 
yading@10:     ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: static int config_input(AVFilterLink *inlink)
yading@10: {
yading@10:     AVFilterContext *ctx = inlink->dst;
yading@10:     HisteqContext *histeq = ctx->priv;
yading@10:     const AVPixFmtDescriptor *pix_desc = av_pix_fmt_desc_get(inlink->format);
yading@10: 
yading@10:     histeq->bpp = av_get_bits_per_pixel(pix_desc) / 8;
yading@10:     ff_fill_rgba_map(histeq->rgba_map, inlink->format);
yading@10: 
yading@10:     return 0;
yading@10: }
yading@10: 
yading@10: #define R 0
yading@10: #define G 1
yading@10: #define B 2
yading@10: #define A 3
yading@10: 
yading@10: #define GET_RGB_VALUES(r, g, b, src, map) do { \
yading@10:     r = src[x + map[R]];                       \
yading@10:     g = src[x + map[G]];                       \
yading@10:     b = src[x + map[B]];                       \
yading@10: } while (0)
yading@10: 
yading@10: static int filter_frame(AVFilterLink *inlink, AVFrame *inpic)
yading@10: {
yading@10:     AVFilterContext   *ctx     = inlink->dst;
yading@10:     HisteqContext     *histeq  = ctx->priv;
yading@10:     AVFilterLink      *outlink = ctx->outputs[0];
yading@10:     int strength  = histeq->strength  * 1000;
yading@10:     int intensity = histeq->intensity * 1000;
yading@10:     int x, y, i, luthi, lutlo, lut, luma, oluma, m;
yading@10:     AVFrame *outpic;
yading@10:     unsigned int r, g, b, jran;
yading@10:     uint8_t *src, *dst;
yading@10: 
yading@10:     outpic = ff_get_video_buffer(outlink, outlink->w, outlink->h);
yading@10:     if (!outpic) {
yading@10:         av_frame_free(&inpic);
yading@10:         return AVERROR(ENOMEM);
yading@10:     }
yading@10:     av_frame_copy_props(outpic, inpic);
yading@10: 
yading@10:     /* Seed random generator for antibanding. */
yading@10:     jran = LCG_SEED;
yading@10: 
yading@10:     /* Calculate and store the luminance and calculate the global histogram
yading@10:        based on the luminance. */
yading@10:     memset(histeq->in_histogram, 0, sizeof(histeq->in_histogram));
yading@10:     src = inpic->data[0];
yading@10:     dst = outpic->data[0];
yading@10:     for (y = 0; y < inlink->h; y++) {
yading@10:         for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
yading@10:             GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
yading@10:             luma = (55 * r + 182 * g + 19 * b) >> 8;
yading@10:             dst[x + histeq->rgba_map[A]] = luma;
yading@10:             histeq->in_histogram[luma]++;
yading@10:         }
yading@10:         src += inpic->linesize[0];
yading@10:         dst += outpic->linesize[0];
yading@10:     }
yading@10: 
yading@10: #ifdef DEBUG
yading@10:     for (x = 0; x < 256; x++)
yading@10:         av_dlog(ctx, "in[%d]: %u\n", x, histeq->in_histogram[x]);
yading@10: #endif
yading@10: 
yading@10:     /* Calculate the lookup table. */
yading@10:     histeq->LUT[0] = histeq->in_histogram[0];
yading@10:     /* Accumulate */
yading@10:     for (x = 1; x < 256; x++)
yading@10:         histeq->LUT[x] = histeq->LUT[x-1] + histeq->in_histogram[x];
yading@10: 
yading@10:     /* Normalize */
yading@10:     for (x = 0; x < 256; x++)
yading@10:         histeq->LUT[x] = (histeq->LUT[x] * intensity) / (inlink->h * inlink->w);
yading@10: 
yading@10:     /* Adjust the LUT based on the selected strength. This is an alpha
yading@10:        mix of the calculated LUT and a linear LUT with gain 1. */
yading@10:     for (x = 0; x < 256; x++)
yading@10:         histeq->LUT[x] = (strength * histeq->LUT[x]) / 255 +
yading@10:                          ((255 - strength) * x)      / 255;
yading@10: 
yading@10:     /* Output the equalized frame. */
yading@10:     memset(histeq->out_histogram, 0, sizeof(histeq->out_histogram));
yading@10: 
yading@10:     src = inpic->data[0];
yading@10:     dst = outpic->data[0];
yading@10:     for (y = 0; y < inlink->h; y++) {
yading@10:         for (x = 0; x < inlink->w * histeq->bpp; x += histeq->bpp) {
yading@10:             luma = dst[x + histeq->rgba_map[A]];
yading@10:             if (luma == 0) {
yading@10:                 for (i = 0; i < histeq->bpp; ++i)
yading@10:                     dst[x + i] = 0;
yading@10:                 histeq->out_histogram[0]++;
yading@10:             } else {
yading@10:                 lut = histeq->LUT[luma];
yading@10:                 if (histeq->antibanding != HISTEQ_ANTIBANDING_NONE) {
yading@10:                     if (luma > 0) {
yading@10:                         lutlo = histeq->antibanding == HISTEQ_ANTIBANDING_WEAK ?
yading@10:                                 (histeq->LUT[luma] + histeq->LUT[luma - 1]) / 2 :
yading@10:                                  histeq->LUT[luma - 1];
yading@10:                     } else
yading@10:                         lutlo = lut;
yading@10: 
yading@10:                     if (luma < 255) {
yading@10:                         luthi = (histeq->antibanding == HISTEQ_ANTIBANDING_WEAK) ?
yading@10:                             (histeq->LUT[luma] + histeq->LUT[luma + 1]) / 2 :
yading@10:                              histeq->LUT[luma + 1];
yading@10:                     } else
yading@10:                         luthi = lut;
yading@10: 
yading@10:                     if (lutlo != luthi) {
yading@10:                         jran = LCG(jran);
yading@10:                         lut = lutlo + ((luthi - lutlo + 1) * jran) / LCG_M;
yading@10:                     }
yading@10:                 }
yading@10: 
yading@10:                 GET_RGB_VALUES(r, g, b, src, histeq->rgba_map);
yading@10:                 if (((m = FFMAX3(r, g, b)) * lut) / luma > 255) {
yading@10:                     r = (r * 255) / m;
yading@10:                     g = (g * 255) / m;
yading@10:                     b = (b * 255) / m;
yading@10:                 } else {
yading@10:                     r = (r * lut) / luma;
yading@10:                     g = (g * lut) / luma;
yading@10:                     b = (b * lut) / luma;
yading@10:                 }
yading@10:                 dst[x + histeq->rgba_map[R]] = r;
yading@10:                 dst[x + histeq->rgba_map[G]] = g;
yading@10:                 dst[x + histeq->rgba_map[B]] = b;
yading@10:                 oluma = av_clip_uint8((55 * r + 182 * g + 19 * b) >> 8);
yading@10:                 histeq->out_histogram[oluma]++;
yading@10:             }
yading@10:         }
yading@10:         src += inpic->linesize[0];
yading@10:         dst += outpic->linesize[0];
yading@10:     }
yading@10: #ifdef DEBUG
yading@10:     for (x = 0; x < 256; x++)
yading@10:         av_dlog(ctx, "out[%d]: %u\n", x, histeq->out_histogram[x]);
yading@10: #endif
yading@10: 
yading@10:     av_frame_free(&inpic);
yading@10:     return ff_filter_frame(outlink, outpic);
yading@10: }
yading@10: 
yading@10: static const AVFilterPad histeq_inputs[] = {
yading@10:     {
yading@10:         .name             = "default",
yading@10:         .type             = AVMEDIA_TYPE_VIDEO,
yading@10:         .config_props     = config_input,
yading@10:         .filter_frame     = filter_frame,
yading@10:     },
yading@10:     { NULL }
yading@10: };
yading@10: 
yading@10: static const AVFilterPad histeq_outputs[] = {
yading@10:     {
yading@10:         .name             = "default",
yading@10:         .type             = AVMEDIA_TYPE_VIDEO,
yading@10:     },
yading@10:     { NULL }
yading@10: };
yading@10: 
yading@10: AVFilter avfilter_vf_histeq = {
yading@10:     .name          = "histeq",
yading@10:     .description   = NULL_IF_CONFIG_SMALL("Apply global color histogram equalization."),
yading@10:     .priv_size     = sizeof(HisteqContext),
yading@10:     .init          = init,
yading@10:     .query_formats = query_formats,
yading@10: 
yading@10:     .inputs        = histeq_inputs,
yading@10:     .outputs       = histeq_outputs,
yading@10:     .priv_class    = &histeq_class,
yading@10: };