histogram filter

Signed-off-by: Paul B Mahol <onemda@gmail.com>

Changelog

@@ -13,6 +13,7 @@ version <next>:
 - allpass, bass, bandpass, bandreject, biquad, equalizer, highpass, lowpass
   and treble audio filter
 - improved showspectrum filter, with multichannel support and sox-like colors
+- histogram filter
 
 
 version 1.1:

doc/filters.texi

@@ -3098,6 +3098,89 @@ the histogram. Possible values are @code{none}, @code{weak} or
 @code{strong}. It defaults to @code{none}.
 @end table
 
+@section histogram
+
+Compute and draw a color distribution histogram for the input video.
+
+The computed histogram is a representation of distribution of color components
+in an image.
+
+The filter accepts the following named parameters:
+
+@table @option
+@item mode
+Set histogram mode.
+
+It accepts the following values:
+@table @samp
+@item levels
+standard histogram that display color components distribution in an image.
+Displays color graph for each color component. Shows distribution
+of the Y, U, V, A or G, B, R components, depending on input format,
+in current frame. Bellow each graph is color component scale meter.
+
+@item color
+chroma values in vectorscope, if brighter more such chroma values are
+distributed in an image.
+Displays chroma values (U/V color placement) in two dimensional graph
+(which is called a vectorscope). It can be used to read of the hue and
+saturation of the current frame. At a same time it is a histogram.
+The whiter a pixel in the vectorscope, the more pixels of the input frame
+correspond to that pixel (that is the more pixels have this chroma value).
+The V component is displayed on the horizontal (X) axis, with the leftmost
+side being V = 0 and the rightmost side being V = 255.
+The U component is displayed on the vertical (Y) axis, with the top
+representing U = 0 and the bottom representing U = 255.
+
+The position of a white pixel in the graph corresponds to the chroma value
+of a pixel of the input clip. So the graph can be used to read of the
+hue (color flavor) and the saturation (the dominance of the hue in the color).
+As the hue of a color changes, it moves around the square. At the center of
+the square, the saturation is zero, which means that the corresponding pixel
+has no color. If you increase the amount of a specific color, while leaving
+the other colors unchanged, the saturation increases, and you move towards
+the edge of the square.
+
+@item color2
+chroma values in vectorscope, similar as @code{color} but actual chroma values
+are displayed.
+
+@item waveform
+per row/column luminance graph. In row mode the left side represents luma = 0
+and right side represents luma = 255. In column mode top side represends
+luma = 0 and bottom side represents luma = 255.
+@end table
+Default value is @code{levels}.
+
+@item level_height
+Set height of level in @code{levels}. Default value is @code{200}.
+Allowed range is [50, 2048].
+
+@item scale_height
+Set height of color scale in @code{levels}. Default value is @code{12}.
+Allowed range is [0, 40].
+
+@item step
+Set step for @code{waveform} mode. Smaller values are useful to find out how much
+of same luminance values across input rows/columns are distributed.
+Default value is @code{10}. Allowed range is [1, 255].
+
+@item waveform_mode
+Set mode for @code{waveform}. Can be either @code{row}, or @code{column}.
+Default is @code{row}.
+
+@subsection Examples
+
+@itemize
+
+@item
+Calculate and draw histogram:
+@example
+ffplay -i input -vf histogram
+@end example
+
+@end itemize
+
 @section hqdn3d
 
 High precision/quality 3d denoise filter. This filter aims to reduce

libavfilter/Makefile

@@ -122,6 +122,7 @@ OBJS-$(CONFIG_GEQ_FILTER)                    += vf_geq.o
 OBJS-$(CONFIG_GRADFUN_FILTER)                += vf_gradfun.o
 OBJS-$(CONFIG_HFLIP_FILTER)                  += vf_hflip.o
 OBJS-$(CONFIG_HISTEQ_FILTER)                 += vf_histeq.o
+OBJS-$(CONFIG_HISTOGRAM_FILTER)              += vf_histogram.o
 OBJS-$(CONFIG_HQDN3D_FILTER)                 += vf_hqdn3d.o
 OBJS-$(CONFIG_HUE_FILTER)                    += vf_hue.o
 OBJS-$(CONFIG_IDET_FILTER)                   += vf_idet.o

libavfilter/allfilters.c

@@ -116,6 +116,7 @@ void avfilter_register_all(void)
     REGISTER_FILTER(GRADFUN,        gradfun,        vf);
     REGISTER_FILTER(HFLIP,          hflip,          vf);
     REGISTER_FILTER(HISTEQ,         histeq,         vf);
+    REGISTER_FILTER(HISTOGRAM,      histogram,      vf);
     REGISTER_FILTER(HQDN3D,         hqdn3d,         vf);
     REGISTER_FILTER(HUE,            hue,            vf);
     REGISTER_FILTER(IDET,           idet,           vf);

libavfilter/version.h

@@ -29,8 +29,8 @@
 #include "libavutil/avutil.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  3
-#define LIBAVFILTER_VERSION_MINOR  35
-#define LIBAVFILTER_VERSION_MICRO 101
+#define LIBAVFILTER_VERSION_MINOR  36
+#define LIBAVFILTER_VERSION_MICRO 100
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \
                                                LIBAVFILTER_VERSION_MINOR, \

libavfilter/vf_histogram.c

+/*
+ * Copyright (c) 2012-2013 Paul B Mahol
+ *
+ * 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
+ */
+
+#include "libavutil/avassert.h"
+#include "libavutil/opt.h"
+#include "libavutil/parseutils.h"
+#include "libavutil/pixdesc.h"
+#include "avfilter.h"
+#include "formats.h"
+#include "internal.h"
+#include "video.h"
+
+enum HistogramMode {
+    MODE_LEVELS,
+    MODE_WAVEFORM,
+    MODE_COLOR,
+    MODE_COLOR2,
+    MODE_NB
+};
+
+typedef struct HistogramContext {
+    const AVClass *class;               ///< AVClass context for log and options purpose
+    enum HistogramMode mode;
+    unsigned       histogram[256];
+    unsigned       max_hval;
+    int            ncomp;
+    const uint8_t  *bg_color;
+    const uint8_t  *fg_color;
+    int            level_height;
+    int            scale_height;
+    int            step;
+    int            waveform_mode;
+} HistogramContext;
+
+#define OFFSET(x) offsetof(HistogramContext, x)
+#define FLAGS AV_OPT_FLAG_FILTERING_PARAM|AV_OPT_FLAG_VIDEO_PARAM
+
+static const AVOption histogram_options[] = {
+    { "mode", "set histogram mode", OFFSET(mode), AV_OPT_TYPE_INT, {.i64=MODE_LEVELS}, 0, MODE_NB-1, FLAGS, "mode"},
+    { "levels", "standard histogram", 0, AV_OPT_TYPE_CONST, {.i64=MODE_LEVELS}, 0, 0, FLAGS, "mode" },
+    { "waveform", "per row/column luminance graph", 0, AV_OPT_TYPE_CONST, {.i64=MODE_WAVEFORM}, 0, 0, FLAGS, "mode" },
+    { "color", "chroma values in vectorscope", 0, AV_OPT_TYPE_CONST, {.i64=MODE_COLOR}, 0, 0, FLAGS, "mode" },
+    { "color2", "chroma values in vectorscope", 0, AV_OPT_TYPE_CONST, {.i64=MODE_COLOR2}, 0, 0, FLAGS, "mode" },
+    { "level_height", "set level height", OFFSET(level_height), AV_OPT_TYPE_INT, {.i64=200}, 50, 2048, FLAGS},
+    { "scale_height", "set scale height", OFFSET(scale_height), AV_OPT_TYPE_INT, {.i64=12}, 0, 40, FLAGS},
+    { "step", "set waveform step value", OFFSET(step), AV_OPT_TYPE_INT, {.i64=10}, 1, 255, FLAGS},
+    { "waveform_mode", "set waveform mode", OFFSET(waveform_mode), AV_OPT_TYPE_INT, {.i64=0}, 0, 1, FLAGS, "waveform_mode"},
+    { "row",   NULL, 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "waveform_mode" },
+    { "column", NULL, 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "waveform_mode" },
+    { NULL },
+};
+
+AVFILTER_DEFINE_CLASS(histogram);
+
+static av_cold int init(AVFilterContext *ctx, const char *args)
+{
+    HistogramContext *h = ctx->priv;
+    int ret;
+
+    h->class = &histogram_class;
+    av_opt_set_defaults(h);
+
+    if ((ret = (av_set_options_string(h, args, "=", ":"))) < 0)
+        return ret;
+
+    return 0;
+}
+
+static const enum AVPixelFormat color_pix_fmts[] = {
+    AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVJ444P,
+    AV_PIX_FMT_NONE
+};
+
+static const enum AVPixelFormat levels_pix_fmts[] = {
+    AV_PIX_FMT_YUV444P, AV_PIX_FMT_YUVA444P, AV_PIX_FMT_YUVJ444P,
+    AV_PIX_FMT_GRAY8, AV_PIX_FMT_GBRP, AV_PIX_FMT_NONE
+};
+
+static int query_formats(AVFilterContext *ctx)
+{
+    HistogramContext *h = ctx->priv;
+    const enum AVPixelFormat *pix_fmts;
+
+    switch (h->mode) {
+    case MODE_LEVELS:
+        pix_fmts = levels_pix_fmts;
+        break;
+    case MODE_WAVEFORM:
+    case MODE_COLOR:
+    case MODE_COLOR2:
+        pix_fmts = color_pix_fmts;
+        break;
+    default:
+        av_assert0(0);
+    }
+
+    ff_set_common_formats(ctx, ff_make_format_list(pix_fmts));
+
+    return 0;
+}
+
+static const uint8_t black_yuva_color[4] = { 0, 127, 127, 255 };
+static const uint8_t black_gbrp_color[4] = { 0, 0, 0, 255 };
+static const uint8_t white_yuva_color[4] = { 255, 127, 127, 255 };
+static const uint8_t white_gbrp_color[4] = { 255, 255, 255, 255 };
+
+static int config_input(AVFilterLink *inlink)
+{
+    HistogramContext *h = inlink->dst->priv;
+    const AVPixFmtDescriptor *desc = av_pix_fmt_desc_get(inlink->format);
+
+    h->ncomp = desc->nb_components;
+
+    switch (inlink->format) {
+    case AV_PIX_FMT_GBRP:
+        h->bg_color = black_gbrp_color;
+        h->fg_color = white_gbrp_color;
+        break;
+    default:
+        h->bg_color = black_yuva_color;
+        h->fg_color = white_yuva_color;
+    }
+
+    return 0;
+}
+
+static int config_output(AVFilterLink *outlink)
+{
+    AVFilterContext *ctx = outlink->src;
+    HistogramContext *h = ctx->priv;
+
+    switch (h->mode) {
+    case MODE_LEVELS:
+        outlink->w = 256;
+        outlink->h = (h->level_height + h->scale_height) * h->ncomp;
+        break;
+    case MODE_WAVEFORM:
+        if (h->waveform_mode)
+            outlink->h = 256;
+        else
+            outlink->w = 256;
+        break;
+    case MODE_COLOR:
+    case MODE_COLOR2:
+        outlink->h = outlink->w = 256;
+        break;
+    default:
+        av_assert0(0);
+    }
+
+    outlink->sample_aspect_ratio = (AVRational){1,1};
+
+    return 0;
+}
+
+static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *in)
+{
+    HistogramContext *h   = inlink->dst->priv;
+    AVFilterContext *ctx  = inlink->dst;
+    AVFilterLink *outlink = ctx->outputs[0];
+    AVFilterBufferRef *out;
+    const uint8_t *src;
+    uint8_t *dst;
+    int i, j, k, l, ret;
+
+    out = ff_get_video_buffer(outlink, AV_PERM_WRITE, outlink->w, outlink->h);
+    if (!out) {
+        avfilter_unref_bufferp(&in);
+        return AVERROR(ENOMEM);
+    }
+
+    out->pts = in->pts;
+    out->pos = in->pos;
+
+    for (k = 0; k < h->ncomp; k++)
+        for (i = 0; i < outlink->h; i++)
+            memset(out->data[k] + i * out->linesize[k], h->bg_color[k], outlink->w);
+
+    switch (h->mode) {
+    case MODE_LEVELS:
+        for (k = 0; k < h->ncomp; k++) {
+            for (i = 0; i < in->video->h; i++) {
+                src = in->data[k] + i * in->linesize[k];
+                for (j = 0; j < in->video->w; j++)
+                    h->histogram[src[j]]++;
+            }
+
+            for (i = 0; i < 256; i++)
+                h->max_hval = FFMAX(h->max_hval, h->histogram[i]);
+
+            int start = k * (h->level_height + h->scale_height);
+            for (i = 0; i < outlink->w; i++) {
+                int col_height = h->level_height - (float)h->histogram[i] / h->max_hval * h->level_height;
+
+                for (j = h->level_height - 1; j >= col_height; j--)
+                    for (l = 0; l < h->ncomp; l++)
+                        out->data[l][(j + start) * out->linesize[l] + i] = h->fg_color[l];
+                for (j = h->level_height + h->scale_height - 1; j >= h->level_height; j--)
+                    out->data[k][(j + start) * out->linesize[k] + i] = i;
+            }
+
+            memset(h->histogram, 0, 256 * sizeof(unsigned));
+            h->max_hval = 0;
+        }
+        break;
+    case MODE_WAVEFORM:
+        if (h->waveform_mode) {
+            for (i = 0; i < inlink->w; i++) {
+                for (j = 0; j < inlink->h; j++) {
+                    int pos = in->data[0][j * in->linesize[0] + i] * out->linesize[0] + i;
+                    unsigned value = out->data[0][pos];
+                    value = FFMIN(value + h->step, 255);
+                    out->data[0][pos] = value;
+                }
+            }
+        } else {
+            for (i = 0; i < inlink->h; i++) {
+                src = in ->data[0] + i * in ->linesize[0];
+                dst = out->data[0] + i * out->linesize[0];
+                for (j = 0; j < inlink->w; j++) {
+                    int pos = src[j];
+                    unsigned value = dst[pos];
+                    value = FFMIN(value + h->step, 255);
+                    dst[pos] = value;
+                }
+            }
+        }
+        break;
+    case MODE_COLOR:
+        for (i = 0; i < inlink->h; i++) {
+            int iw1 = i * in->linesize[1];
+            int iw2 = i * in->linesize[2];
+            for (j = 0; j < inlink->w; j++) {
+                int pos = in->data[1][iw1 + j] * out->linesize[0] + in->data[2][iw2 + j];
+                if (out->data[0][pos] < 255)
+                    out->data[0][pos]++;
+            }
+        }
+        for (i = 0; i < 256; i++) {
+            dst = out->data[0] + i * out->linesize[0];
+            for (j = 0; j < 256; j++) {
+                if (!dst[j]) {
+                    out->data[1][i * out->linesize[0] + j] = i;
+                    out->data[2][i * out->linesize[0] + j] = j;
+                }
+            }
+        }
+        break;
+    case MODE_COLOR2:
+        for (i = 0; i < inlink->h; i++) {
+            int iw1 = i * in->linesize[1];
+            int iw2 = i * in->linesize[2];
+            for (j = 0; j < inlink->w; j++) {
+                int u = in->data[1][iw1 + j];
+                int v = in->data[2][iw2 + j];
+                int pos = u * out->linesize[0] + v;
+                if (!out->data[0][pos])
+                    out->data[0][pos] = FFABS(128 - u) + FFABS(128 - v);
+                out->data[1][pos] = u;
+                out->data[2][pos] = v;
+            }
+        }
+        break;
+    default:
+        av_assert0(0);
+    }
+
+    ret = ff_filter_frame(outlink, out);
+    avfilter_unref_bufferp(&in);
+    if (ret < 0)
+        return ret;
+    return 0;
+}
+
+static av_cold void uninit(AVFilterContext *ctx)
+{
+    HistogramContext *h = ctx->priv;
+
+    av_opt_free(h);
+}
+
+static const AVFilterPad inputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .filter_frame = filter_frame,
+        .config_props = config_input,
+        .min_perms    = AV_PERM_READ,
+    },
+    { NULL }
+};
+
+static const AVFilterPad outputs[] = {
+    {
+        .name         = "default",
+        .type         = AVMEDIA_TYPE_VIDEO,
+        .config_props = config_output,
+    },
+    { NULL }
+};
+
+AVFilter avfilter_vf_histogram = {
+    .name          = "histogram",
+    .description   = NULL_IF_CONFIG_SMALL("Compute and draw a histogram."),
+    .priv_size     = sizeof(HistogramContext),
+    .init          = init,
+    .uninit        = uninit,
+    .query_formats = query_formats,
+    .inputs        = inputs,
+    .outputs       = outputs,
+    .priv_class    = &histogram_class,
+};