libavfilter/vf_nlmeans.c
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 /*
  * Copyright (c) 2016 Clément Bœsch <u pkh me>
  *
  * This file is part of FFmpeg.
  *
  * FFmpeg is free software; you can redistribute it and/or
  * modify it under the terms of the GNU Lesser General Public
  * License as published by the Free Software Foundation; either
  * version 2.1 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
  * Lesser General Public License for more details.
  *
  * You should have received a copy of the GNU Lesser 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
  */
 
 /**
  * @todo
  * - SIMD for compute_safe_ssd_integral_image
  * - SIMD for final weighted averaging
  * - better automatic defaults? see "Parameters" @ http://www.ipol.im/pub/art/2011/bcm_nlm/
  * - temporal support (probably doesn't need any displacement according to
  *   "Denoising image sequences does not require motion estimation")
  * - Bayer pixel format support for at least raw photos? (DNG support would be
  *   handy here)
  * - FATE test (probably needs visual threshold test mechanism due to the use
  *   of floats)
  */
 
 #include "libavutil/avassert.h"
 #include "libavutil/opt.h"
 #include "libavutil/pixdesc.h"
 #include "avfilter.h"
 #include "formats.h"
 #include "internal.h"
 #include "video.h"
 
 struct weighted_avg {
     double total_weight;
     double sum;
 };
 
 #define WEIGHT_LUT_NBITS 9
 #define WEIGHT_LUT_SIZE  (1<<WEIGHT_LUT_NBITS)
 
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 typedef struct NLMeansContext {
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     const AVClass *class;
     int nb_planes;
     int chroma_w, chroma_h;
     double pdiff_scale;                         // invert of the filtering parameter (sigma*10) squared
     double sigma;                               // denoising strength
     int patch_size,    patch_hsize;             // patch size and half size
     int patch_size_uv, patch_hsize_uv;          // patch size and half size for chroma planes
     int research_size,    research_hsize;       // research size and half size
     int research_size_uv, research_hsize_uv;    // research size and half size for chroma planes
     uint32_t *ii_orig;                          // integral image
     uint32_t *ii;                               // integral image starting after the 0-line and 0-column
     int ii_w, ii_h;                             // width and height of the integral image
     int ii_lz_32;                               // linesize in 32-bit units of the integral image
     struct weighted_avg *wa;                    // weighted average of every pixel
     int wa_linesize;                            // linesize for wa in struct size unit
     double weight_lut[WEIGHT_LUT_SIZE];         // lookup table mapping (scaled) patch differences to their associated weights
     double pdiff_lut_scale;                     // scale factor for patch differences before looking into the LUT
     int max_meaningful_diff;                    // maximum difference considered (if the patch difference is too high we ignore the pixel)
 } NLMeansContext;
 
 #define OFFSET(x) offsetof(NLMeansContext, x)
 #define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
 static const AVOption nlmeans_options[] = {
     { "s",  "denoising strength", OFFSET(sigma), AV_OPT_TYPE_DOUBLE, { .dbl = 1.0 }, 1.0, 30.0, FLAGS },
     { "p",  "patch size",                   OFFSET(patch_size),    AV_OPT_TYPE_INT, { .i64 = 3*2+1 }, 0, 99, FLAGS },
     { "pc", "patch size for chroma planes", OFFSET(patch_size_uv), AV_OPT_TYPE_INT, { .i64 = 0 },     0, 99, FLAGS },
     { "r",  "research window",                   OFFSET(research_size),    AV_OPT_TYPE_INT, { .i64 = 7*2+1 }, 0, 99, FLAGS },
     { "rc", "research window for chroma planes", OFFSET(research_size_uv), AV_OPT_TYPE_INT, { .i64 = 0 },     0, 99, FLAGS },
     { NULL }
 };
 
 AVFILTER_DEFINE_CLASS(nlmeans);
 
 static int query_formats(AVFilterContext *ctx)
 {
     static const enum AVPixelFormat pix_fmts[] = {
         AV_PIX_FMT_YUV410P, AV_PIX_FMT_YUV411P,
         AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P,
         AV_PIX_FMT_YUV440P, AV_PIX_FMT_YUV444P,
         AV_PIX_FMT_YUVJ444P, AV_PIX_FMT_YUVJ440P,
         AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ420P,
         AV_PIX_FMT_YUVJ411P,
         AV_PIX_FMT_GRAY8, AV_PIX_FMT_GBRP,
         AV_PIX_FMT_NONE
     };
 
     AVFilterFormats *fmts_list = ff_make_format_list(pix_fmts);
     if (!fmts_list)
         return AVERROR(ENOMEM);
     return ff_set_common_formats(ctx, fmts_list);
 }
 
 /*
  * M is a discrete map where every entry contains the sum of all the entries
  * in the rectangle from the top-left origin of M to its coordinate. In the
  * following schema, "i" contains the sum of the whole map:
  *
  * M = +----------+-----------------+----+
  *     |          |                 |    |
  *     |          |                 |    |
  *     |         a|                b|   c|
  *     +----------+-----------------+----+
  *     |          |                 |    |
  *     |          |                 |    |
  *     |          |        X        |    |
  *     |          |                 |    |
  *     |         d|                e|   f|
  *     +----------+-----------------+----+
  *     |          |                 |    |
  *     |         g|                h|   i|
  *     +----------+-----------------+----+
  *
  * The sum of the X box can be calculated with:
  *    X = e-d-b+a
  *
  * See https://en.wikipedia.org/wiki/Summed_area_table
  *
  * The compute*_ssd functions compute the integral image M where every entry
  * contains the sum of the squared difference of every corresponding pixels of
  * two input planes of the same size as M.
  */
 static inline int get_integral_patch_value(const uint32_t *ii, int ii_lz_32, int x, int y, int p)
 {
     const int e = ii[(y + p    ) * ii_lz_32 + (x + p    )];
     const int d = ii[(y + p    ) * ii_lz_32 + (x - p - 1)];
     const int b = ii[(y - p - 1) * ii_lz_32 + (x + p    )];
     const int a = ii[(y - p - 1) * ii_lz_32 + (x - p - 1)];
     return e - d - b + a;
 }
 
 /**
  * Compute squared difference of the safe area (the zone where s1 and s2
  * overlap). It is likely the largest integral zone, so it is interesting to do
  * as little checks as possible; contrary to the unsafe version of this
  * function, we do not need any clipping here.
  *
  * The line above dst and the column to its left are always readable.
  *
  * This C version computes the SSD integral image using a scalar accumulator,
  * while for SIMD implementation it is likely more interesting to use the
  * two-loops algorithm variant.
  */
 static void compute_safe_ssd_integral_image_c(uint32_t *dst, int dst_linesize_32,
                                               const uint8_t *s1, int linesize1,
                                               const uint8_t *s2, int linesize2,
                                               int w, int h)
 {
     int x, y;
 
     for (y = 0; y < h; y++) {
         uint32_t acc = dst[-1] - dst[-dst_linesize_32 - 1];
 
         for (x = 0; x < w; x++) {
             const int d  = s1[x] - s2[x];
             acc += d * d;
             dst[x] = dst[-dst_linesize_32 + x] + acc;
         }
         s1  += linesize1;
         s2  += linesize2;
         dst += dst_linesize_32;
     }
 }
 
 /**
  * Compute squared difference of an unsafe area (the zone nor s1 nor s2 could
  * be readable).
  *
  * On the other hand, the line above dst and the column to its left are always
  * readable.
  *
  * There is little point in having this function SIMDified as it is likely too
  * complex and only handle small portions of the image.
  *
  * @param dst               integral image
  * @param dst_linesize_32   integral image linesize (in 32-bit integers unit)
  * @param startx            integral starting x position
  * @param starty            integral starting y position
  * @param src               source plane buffer
  * @param linesize          source plane linesize
  * @param offx              source offsetting in x
  * @param offy              source offsetting in y
  * @paran r                 absolute maximum source offsetting
  * @param sw                source width
  * @param sh                source height
  * @param w                 width to compute
  * @param h                 height to compute
  */
 static inline void compute_unsafe_ssd_integral_image(uint32_t *dst, int dst_linesize_32,
                                                      int startx, int starty,
                                                      const uint8_t *src, int linesize,
                                                      int offx, int offy, int r, int sw, int sh,
                                                      int w, int h)
 {
     int x, y;
 
     for (y = starty; y < starty + h; y++) {
         uint32_t acc = dst[y*dst_linesize_32 + startx - 1] - dst[(y-1)*dst_linesize_32 + startx - 1];
         const int s1y = av_clip(y -  r,         0, sh - 1);
         const int s2y = av_clip(y - (r + offy), 0, sh - 1);
 
         for (x = startx; x < startx + w; x++) {
             const int s1x = av_clip(x -  r,         0, sw - 1);
             const int s2x = av_clip(x - (r + offx), 0, sw - 1);
             const uint8_t v1 = src[s1y*linesize + s1x];
             const uint8_t v2 = src[s2y*linesize + s2x];
             const int d = v1 - v2;
             acc += d * d;
             dst[y*dst_linesize_32 + x] = dst[(y-1)*dst_linesize_32 + x] + acc;
         }
     }
 }
 
 /*
  * Compute the sum of squared difference integral image
  * http://www.ipol.im/pub/art/2014/57/
  * Integral Images for Block Matching - Gabriele Facciolo, Nicolas Limare, Enric Meinhardt-Llopis
  *
  * @param ii                integral image of dimension (w+e*2) x (h+e*2) with
  *                          an additional zeroed top line and column already
  *                          "applied" to the pointer value
  * @param ii_linesize_32    integral image linesize (in 32-bit integers unit)
  * @param src               source plane buffer
  * @param linesize          source plane linesize
  * @param offx              x-offsetting ranging in [-e;e]
  * @param offy              y-offsetting ranging in [-e;e]
  * @param w                 source width
  * @param h                 source height
  * @param e                 research padding edge
  */
 static void compute_ssd_integral_image(uint32_t *ii, int ii_linesize_32,
                                        const uint8_t *src, int linesize, int offx, int offy,
                                        int e, int w, int h)
 {
     // ii has a surrounding padding of thickness "e"
     const int ii_w = w + e*2;
     const int ii_h = h + e*2;
 
     // we center the first source
     const int s1x = e;
     const int s1y = e;
 
     // 2nd source is the frame with offsetting
     const int s2x = e + offx;
     const int s2y = e + offy;
 
     // get the dimension of the overlapping rectangle where it is always safe
     // to compare the 2 sources pixels
     const int startx_safe = FFMAX(s1x, s2x);
     const int starty_safe = FFMAX(s1y, s2y);
     const int endx_safe   = FFMIN(s1x + w, s2x + w);
     const int endy_safe   = FFMIN(s1y + h, s2y + h);
 
     // top part where only one of s1 and s2 is still readable, or none at all
     compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                       0, 0,
                                       src, linesize,
                                       offx, offy, e, w, h,
                                       ii_w, starty_safe);
 
     // fill the left column integral required to compute the central
     // overlapping one
     compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                       0, starty_safe,
                                       src, linesize,
                                       offx, offy, e, w, h,
                                       startx_safe, endy_safe - starty_safe);
 
     // main and safe part of the integral
     av_assert1(startx_safe - s1x >= 0); av_assert1(startx_safe - s1x < w);
     av_assert1(starty_safe - s1y >= 0); av_assert1(starty_safe - s1y < h);
     av_assert1(startx_safe - s2x >= 0); av_assert1(startx_safe - s2x < w);
     av_assert1(starty_safe - s2y >= 0); av_assert1(starty_safe - s2y < h);
     compute_safe_ssd_integral_image_c(ii + starty_safe*ii_linesize_32 + startx_safe, ii_linesize_32,
                                       src + (starty_safe - s1y) * linesize + (startx_safe - s1x), linesize,
                                       src + (starty_safe - s2y) * linesize + (startx_safe - s2x), linesize,
                                       endx_safe - startx_safe, endy_safe - starty_safe);
 
     // right part of the integral
     compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                       endx_safe, starty_safe,
                                       src, linesize,
                                       offx, offy, e, w, h,
                                       ii_w - endx_safe, endy_safe - starty_safe);
 
     // bottom part where only one of s1 and s2 is still readable, or none at all
     compute_unsafe_ssd_integral_image(ii, ii_linesize_32,
                                       0, endy_safe,
                                       src, linesize,
                                       offx, offy, e, w, h,
                                       ii_w, ii_h - endy_safe);
 }
 
 static int config_input(AVFilterLink *inlink)
 {
     AVFilterContext *ctx = inlink->dst;
     NLMeansContext *s = ctx->priv;
     const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
     const int e = FFMAX(s->research_hsize, s->research_hsize_uv)
                 + FFMAX(s->patch_hsize,    s->patch_hsize_uv);
 
     s->chroma_w = FF_CEIL_RSHIFT(inlink->w, desc->log2_chroma_w);
     s->chroma_h = FF_CEIL_RSHIFT(inlink->h, desc->log2_chroma_h);
     s->nb_planes = av_pix_fmt_count_planes(inlink->format);
 
     /* Allocate the integral image with extra edges of thickness "e"
      *
      *   +_+-------------------------------+
      *   |0|0000000000000000000000000000000|
      *   +-x-------------------------------+
      *   |0|\    ^                         |
      *   |0| ii  | e                       |
      *   |0|     v                         |
      *   |0|   +-----------------------+   |
      *   |0|   |                       |   |
      *   |0|<->|                       |   |
      *   |0| e |                       |   |
      *   |0|   |                       |   |
      *   |0|   +-----------------------+   |
      *   |0|                               |
      *   |0|                               |
      *   |0|                               |
      *   +-+-------------------------------+
      */
     s->ii_w = inlink->w + e*2;
     s->ii_h = inlink->h + e*2;
 
     // align to 4 the linesize, "+1" is for the space of the left 0-column
     s->ii_lz_32 = FFALIGN(s->ii_w + 1, 4);
 
     // "+1" is for the space of the top 0-line
     s->ii_orig = av_mallocz_array(s->ii_h + 1, s->ii_lz_32 * sizeof(*s->ii_orig));
     if (!s->ii_orig)
         return AVERROR(ENOMEM);
 
     // skip top 0-line and left 0-column
     s->ii = s->ii_orig + s->ii_lz_32 + 1;
 
     // allocate weighted average for every pixel
     s->wa_linesize = inlink->w;
     s->wa = av_malloc_array(s->wa_linesize, inlink->h * sizeof(*s->wa));
     if (!s->wa)
         return AVERROR(ENOMEM);
 
     return 0;
 }
 
 struct thread_data {
     const uint8_t *src;
     int src_linesize;
     int startx, starty;
     int endx, endy;
     const uint32_t *ii_start;
     int p;
 };
 
 static int nlmeans_slice(AVFilterContext *ctx, void *arg, int jobnr, int nb_jobs)
 {
     int x, y;
     NLMeansContext *s = ctx->priv;
     const struct thread_data *td = arg;
     const uint8_t *src = td->src;
     const int src_linesize = td->src_linesize;
     const int process_h = td->endy - td->starty;
     const int slice_start = (process_h *  jobnr   ) / nb_jobs;
     const int slice_end   = (process_h * (jobnr+1)) / nb_jobs;
     const int starty = td->starty + slice_start;
     const int endy   = td->starty + slice_end;
 
     for (y = starty; y < endy; y++) {
         for (x = td->startx; x < td->endx; x++) {
             const int patch_diff_sq = get_integral_patch_value(td->ii_start, s->ii_lz_32, x, y, td->p);
             if (patch_diff_sq < s->max_meaningful_diff) {
                 struct weighted_avg *wa = &s->wa[y*s->wa_linesize + x];
                 const int weight_lut_idx = patch_diff_sq * s->pdiff_lut_scale;
                 const double weight = s->weight_lut[weight_lut_idx]; // exp(-patch_diff_sq * s->pdiff_scale)
                 wa->total_weight += weight;
                 wa->sum += weight * src[y*src_linesize + x];
             }
         }
     }
     return 0;
 }
 
 static int nlmeans_plane(AVFilterContext *ctx, int w, int h, int p, int r,
                          uint8_t *dst, int dst_linesize,
                          const uint8_t *src, int src_linesize)
 {
     int x, y;
     int offx, offy;
     NLMeansContext *s = ctx->priv;
     /* patches center points cover the whole research window so the patches
      * themselves overflow the research window */
     const int e = r + p;
     /* focus an integral pointer on the centered image (s1) */
     const uint32_t *centered_ii = s->ii + e*s->ii_lz_32 + e;
 
     memset(s->wa, 0, s->wa_linesize * h * sizeof(*s->wa));
 
     for (offy = -r; offy <= r; offy++) {
         for (offx = -r; offx <= r; offx++) {
             if (offx || offy) {
                 struct thread_data td = {
                     .src          = src + offy*src_linesize + offx,
                     .src_linesize = src_linesize,
                     .startx       = FFMAX(0, -offx),
                     .starty       = FFMAX(0, -offy),
                     .endx         = FFMIN(w, w - offx),
                     .endy         = FFMIN(h, h - offy),
                     .ii_start     = centered_ii + offy*s->ii_lz_32 + offx,
                     .p            = p,
                 };
 
                 compute_ssd_integral_image(s->ii, s->ii_lz_32,
                                            src, src_linesize,
                                            offx, offy, e, w, h);
                 ctx->internal->execute(ctx, nlmeans_slice, &td, NULL,
                                        FFMIN(td.endy - td.starty, ff_filter_get_nb_threads(ctx)));
             }
         }
     }
     for (y = 0; y < h; y++) {
         for (x = 0; x < w; x++) {
             struct weighted_avg *wa = &s->wa[y*s->wa_linesize + x];
 
             // Also weight the centered pixel
             wa->total_weight += 1.0;
             wa->sum += 1.0 * src[y*src_linesize + x];
 
             dst[y*dst_linesize + x] = av_clip_uint8(wa->sum / wa->total_weight);
         }
     }
     return 0;
 }
 
 static int filter_frame(AVFilterLink *inlink, AVFrame *in)
 {
     int i;
     AVFilterContext *ctx = inlink->dst;
     NLMeansContext *s = ctx->priv;
     AVFilterLink *outlink = ctx->outputs[0];
 
     AVFrame *out = ff_get_video_buffer(outlink, outlink->w, outlink->h);
     if (!out) {
         av_frame_free(&in);
         return AVERROR(ENOMEM);
     }
     av_frame_copy_props(out, in);
 
     for (i = 0; i < s->nb_planes; i++) {
         const int w = i ? s->chroma_w          : inlink->w;
         const int h = i ? s->chroma_h          : inlink->h;
         const int p = i ? s->patch_hsize_uv    : s->patch_hsize;
         const int r = i ? s->research_hsize_uv : s->research_hsize;
         nlmeans_plane(ctx, w, h, p, r,
                       out->data[i], out->linesize[i],
                       in->data[i],  in->linesize[i]);
     }
 
     av_frame_free(&in);
     return ff_filter_frame(outlink, out);
 }
 
 #define CHECK_ODD_FIELD(field, name) do {                       \
     if (!(s->field & 1)) {                                      \
         s->field |= 1;                                          \
         av_log(ctx, AV_LOG_WARNING, name " size must be odd, "  \
                "setting it to %d\n", s->field);                 \
     }                                                           \
 } while (0)
 
 static av_cold int init(AVFilterContext *ctx)
 {
     int i;
     NLMeansContext *s = ctx->priv;
     const double h = s->sigma * 10.;
 
     s->pdiff_scale = 1. / (h * h);
     s->max_meaningful_diff = -log(1/255.) / s->pdiff_scale;
     s->pdiff_lut_scale = 1./s->max_meaningful_diff * WEIGHT_LUT_SIZE;
     av_assert0((s->max_meaningful_diff - 1) * s->pdiff_lut_scale < FF_ARRAY_ELEMS(s->weight_lut));
     for (i = 0; i < WEIGHT_LUT_SIZE; i++)
         s->weight_lut[i] = exp(-i / s->pdiff_lut_scale * s->pdiff_scale);
 
     CHECK_ODD_FIELD(research_size,   "Luma research window");
     CHECK_ODD_FIELD(patch_size,      "Luma patch");
 
     if (!s->research_size_uv) s->research_size_uv = s->research_size;
     if (!s->patch_size_uv)    s->patch_size_uv    = s->patch_size;
 
     CHECK_ODD_FIELD(research_size_uv, "Chroma research window");
     CHECK_ODD_FIELD(patch_size_uv,    "Chroma patch");
 
     s->research_hsize    = s->research_size    / 2;
     s->research_hsize_uv = s->research_size_uv / 2;
     s->patch_hsize       = s->patch_size       / 2;
     s->patch_hsize_uv    = s->patch_size_uv    / 2;
 
     av_log(ctx, AV_LOG_INFO, "Research window: %dx%d / %dx%d, patch size: %dx%d / %dx%d\n",
            s->research_size, s->research_size, s->research_size_uv, s->research_size_uv,
            s->patch_size,    s->patch_size,    s->patch_size_uv,    s->patch_size_uv);
 
     return 0;
 }
 
 static av_cold void uninit(AVFilterContext *ctx)
 {
     NLMeansContext *s = ctx->priv;
     av_freep(&s->ii_orig);
     av_freep(&s->wa);
 }
 
 static const AVFilterPad nlmeans_inputs[] = {
     {
         .name         = "default",
         .type         = AVMEDIA_TYPE_VIDEO,
         .config_props = config_input,
         .filter_frame = filter_frame,
     },
     { NULL }
 };
 
 static const AVFilterPad nlmeans_outputs[] = {
     {
         .name = "default",
         .type = AVMEDIA_TYPE_VIDEO,
     },
     { NULL }
 };
 
 AVFilter ff_vf_nlmeans = {
     .name          = "nlmeans",
     .description   = NULL_IF_CONFIG_SMALL("Non-local means denoiser."),
     .priv_size     = sizeof(NLMeansContext),
     .init          = init,
     .uninit        = uninit,
     .query_formats = query_formats,
     .inputs        = nlmeans_inputs,
     .outputs       = nlmeans_outputs,
     .priv_class    = &nlmeans_class,
     .flags         = AVFILTER_FLAG_SUPPORT_TIMELINE_GENERIC | AVFILTER_FLAG_SLICE_THREADS,
 };