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doc/filters/histogram: copyedit for grammar

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There were a few grammar and spelling mistakes in this filter
description. I went through it and corrected them without changing
the meaning.
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Werner Robitza 2014-02-10 18:16:36 +01:00 committed by Paul B Mahol
parent fba1592f35
commit 1ffac25d31
1 changed files with 40 additions and 44 deletions
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doc/filters.texi
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@ -4937,8 +4937,8 @@ the histogram. Possible values are @code{none}, @code{weak} or
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 computed histogram is a representation of the color component
distribution in an image.
The filter accepts the following options:
@ -4949,41 +4949,38 @@ 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 R, G, B components, depending on input format,
in current frame. Bellow each graph is color component scale meter.
Standard histogram that displays the color components distribution in an
image. Displays color graph for each color component. Shows distribution of
the Y, U, V, A or R, G, B components, depending on input format, in the
current frame. Below each graph a color component scale meter is shown.
@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.
Displays chroma values (U/V color placement) in a two dimensional
graph (which is called a vectorscope). The brighter a pixel in the
vectorscope, the more pixels of the input frame correspond to that pixel
(i.e., 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 position of a white pixel in the graph corresponds to the chroma value of
a pixel of the input clip. The graph can therefore be used to read 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 the amount of a specific color is increased (while leaving the other
colors unchanged) the saturation increases, and the indicator moves towards
the edge of the square.
@item color2
chroma values in vectorscope, similar as @code{color} but actual chroma values
Chroma values in vectorscope, similar as @code{color} but actual chroma values
are displayed.
@item waveform
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.
Per row/column color component graph. In row mode, the graph on the left side
represents color component value 0 and the right side represents value = 255.
In column mode, the top side represents color component value = 0 and bottom
side represents value = 255.
@end table
Default value is @code{levels}.
@ -4996,8 +4993,8 @@ 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.
Set step for @code{waveform} mode. Smaller values are useful to find out how
many values of the same luminance are distributed across input rows/columns.
Default value is @code{10}. Allowed range is [1, 255].
@item waveform_mode
@ -5016,26 +5013,25 @@ It accepts the following values:
@table @samp
@item parade
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.
@code{row} waveform mode or one below the other in @code{column} waveform mode
for @code{waveform} histogram mode. For @code{levels} histogram mode,
per color component graphs are placed below each other.
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 width/height.
If not, the correction is easy to make by making adjustments to level the
three waveforms.
Using 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 graphs 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 width/height. If not, the correction is easy to perform by
making level adjustments the three waveforms.
@item overlay
Presents information that's identical to that in the @code{parade}, except
Presents information identical to that in the @code{parade}, except
that the graphs representing color components are superimposed directly
over one another.
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
This display mode in @code{waveform} histogram mode makes it easier to spot
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