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lavfi/histogram: make waveform mode more useful

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Now it displays all color components (not just luma)
either in parade or overlay and also works with RGB colorspace.

Signed-off-by: Paul B Mahol <onemda@gmail.com>
This commit is contained in:
Paul B Mahol
2013-02-09 16:05:28 +00:00
parent da726a8763
commit 4fa9defc7f
2 changed files with 59 additions and 20 deletions
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33
doc/filters.texi
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@@ -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