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lavfi/histogram: overlay display mode for levels histogram mode 

Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol 2013-02-18 20:12:07 +00:00
parent e39821a65e
commit 480ddf2bc9
2 changed files with 25 additions and 16 deletions
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26
doc/filters.texi
View File

@ -3170,29 +3170,33 @@ 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}.
Set display mode for @code{waveform} and @code{levels}.
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.
Display separate graph for the color components side by side in
@code{row} waveform mode or one below other in @code{column} waveform mode
for @code{waveform} histogram mode. For @code{levels} histogram mode
per color component graphs are placed one bellow other.
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
This display mode in @code{waveform} histogram mode makes it 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.
picture should display three waveforms of roughly equal width/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
that the graphs 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.
This display mode in @code{waveform} histogram 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

15
libavfilter/vf_histogram.c
View File

@ -153,7 +153,7 @@ static int config_output(AVFilterLink *outlink)
switch (h->mode) {
case MODE_LEVELS:
outlink->w = 256;
outlink->h = (h->level_height + h->scale_height) * h->ncomp;
outlink->h = (h->level_height + h->scale_height) * FFMAX(h->ncomp * h->display_mode, 1);
break;
case MODE_WAVEFORM:
if (h->waveform_mode)
@ -200,7 +200,7 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *in)
switch (h->mode) {
case MODE_LEVELS:
for (k = 0; k < h->ncomp; k++) {
int start = k * (h->level_height + h->scale_height);
int start = k * (h->level_height + h->scale_height) * h->display_mode;
for (i = 0; i < in->video->h; i++) {
src = in->data[k] + i * in->linesize[k];
@ -214,9 +214,14 @@ static int filter_frame(AVFilterLink *inlink, AVFilterBufferRef *in)
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 - 1; j >= col_height; j--) {
if (h->display_mode) {
for (l = 0; l < h->ncomp; l++)
out->data[l][(j + start) * out->linesize[l] + i] = h->fg_color[l];
} else {
out->data[k][(j + start) * out->linesize[k] + i] = 255;
}
}
for (j = h->level_height + h->scale_height - 1; j >= h->level_height; j--)
out->data[k][(j + start) * out->linesize[k] + i] = i;
}