@@ -3146,9 +3146,9 @@ 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.

+per row/column color component graph. In row mode graph in the left side represents

+color component value 0 and right side represents value = 255. In column mode top

+side represents color component value = 0 and bottom side represents value = 255.

 @end table

 Default value is @code{levels}.

@@ -3168,6 +3168,33 @@ 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}.

+

+@item display_mode

+Set display mode for @code{waveform}.

+It accepts the following values:

+@table @samp

+@item parade

+Display separate waveforms for the color components side by side in

+@code{row} mode or one below other in @code{column} mode.

+

+In this display mode it is easy to spot color casts in the highlights and

+shadows of an image, by comparing the contours of the top and the bottom

+of each waveform. Since whites, grays, and blacks are characterized by

+exactly equal amounts of red, green, and blue, neutral areas of the

+picture should display three waveforms of roughly equal height.

+If not, the correction is easy to make by making adjustments to level the

+three waveforms.

+

+@item overlay

+Presents information that's identical to that in the @code{parade}, except

+that the waveforms representing color components are superimposed directly

+over one another.

+

+This display mode can make it easier to spot the relative differences or

+similarities in overlapping areas of the color components that are supposed

+to be identical, such as neutral whites, grays, or blacks.

+@end table

+Default is @code{parade}.

 @end table

 @subsection Examples

@@ -47,6 +47,7 @@ typedef struct HistogramContext {

     int            scale_height;

     int            step;

     int            waveform_mode;

+    int            display_mode;

 } HistogramContext;

 #define OFFSET(x) offsetof(HistogramContext, x)

@@ -64,6 +65,9 @@ static const AVOption histogram_options[] = {

     { "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" },

+    { "display_mode", "set display mode", OFFSET(display_mode), AV_OPT_TYPE_INT, {.i64=1}, 0, 1, FLAGS, "display_mode"},

+    { "parade",  NULL, 0, AV_OPT_TYPE_CONST, {.i64=1}, 0, 0, FLAGS, "display_mode" },

+    { "overlay", NULL, 0, AV_OPT_TYPE_CONST, {.i64=0}, 0, 0, FLAGS, "display_mode" },

     { NULL },

 };

@@ -99,10 +103,10 @@ static int query_formats(AVFilterContext *ctx)

     const enum AVPixelFormat *pix_fmts;

     switch (h->mode) {

+    case MODE_WAVEFORM:

     case MODE_LEVELS:

         pix_fmts = levels_pix_fmts;

         break;

-    case MODE_WAVEFORM:

     case MODE_COLOR:

     case MODE_COLOR2:

         pix_fmts = color_pix_fmts;

@@ -153,9 +157,9 @@ static int config_output(AVFilterLink *outlink)

         break;

     case MODE_WAVEFORM:

         if (h->waveform_mode)

-            outlink->h = 256;

+            outlink->h = 256 * FFMAX(h->ncomp * h->display_mode, 1);

         else

-            outlink->w = 256;

+            outlink->w = 256 * FFMAX(h->ncomp * h->display_mode, 1);

         break;

     case MODE_COLOR:

     case MODE_COLOR2:

@@ -223,23 +227,31 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *in)

         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;

+            for (k = 0; k < h->ncomp; k++) {

+                int offset = k * 256 * h->display_mode;

+                for (i = 0; i < inlink->w; i++) {

+                    for (j = 0; j < inlink->h; j++) {

+                        int pos = (offset +

+                                   in->data[k][j * in->linesize[k] + i]) *

+                                  out->linesize[k] + i;

+                        unsigned value = out->data[k][pos];

+                        value = FFMIN(value + h->step, 255);

+                        out->data[k][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;

+            for (k = 0; k < h->ncomp; k++) {

+                int offset = k * 256 * h->display_mode;

+                for (i = 0; i < inlink->h; i++) {

+                    src = in ->data[k] + i * in ->linesize[k];

+                    dst = out->data[k] + i * out->linesize[k];

+                    for (j = 0; j < inlink->w; j++) {

+                        int pos = src[j] + offset;

+                        unsigned value = dst[pos];

+                        value = FFMIN(value + h->step, 255);

+                        dst[pos] = value;

+                    }

                 }

             }

         }