doc/filters/histogram: copyedit for grammar

There were a few grammar and spelling mistakes in this filter
description. I went through it and corrected them without changing
the meaning.
This commit is contained in:
Werner Robitza 2014-02-10 18:16:36 +01:00 committed by Paul B Mahol
parent fba1592f35
commit 1ffac25d31

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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. Compute and draw a color distribution histogram for the input video.
The computed histogram is a representation of distribution of color components The computed histogram is a representation of the color component
in an image. distribution in an image.
The filter accepts the following options: The filter accepts the following options:
@ -4949,41 +4949,38 @@ Set histogram mode.
It accepts the following values: It accepts the following values:
@table @samp @table @samp
@item levels @item levels
standard histogram that display color components distribution in an image. Standard histogram that displays the color components distribution in an
Displays color graph for each color component. Shows distribution image. Displays color graph for each color component. Shows distribution of
of the Y, U, V, A or R, G, B components, depending on input format, the Y, U, V, A or R, G, B components, depending on input format, in the
in current frame. Bellow each graph is color component scale meter. current frame. Below each graph a color component scale meter is shown.
@item color @item color
chroma values in vectorscope, if brighter more such chroma values are Displays chroma values (U/V color placement) in a two dimensional
distributed in an image. graph (which is called a vectorscope). The brighter a pixel in the
Displays chroma values (U/V color placement) in two dimensional graph vectorscope, the more pixels of the input frame correspond to that pixel
(which is called a vectorscope). It can be used to read of the hue and (i.e., more pixels have this chroma value). The V component is displayed on
saturation of the current frame. At a same time it is a histogram. the horizontal (X) axis, with the leftmost side being V = 0 and the rightmost
The whiter a pixel in the vectorscope, the more pixels of the input frame side being V = 255. The U component is displayed on the vertical (Y) axis,
correspond to that pixel (that is the more pixels have this chroma value). with the top representing U = 0 and the bottom representing U = 255.
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 The position of a white pixel in the graph corresponds to the chroma value of
of a pixel of the input clip. So the graph can be used to read of the a pixel of the input clip. The graph can therefore be used to read the hue
hue (color flavor) and the saturation (the dominance of the hue in the color). (color flavor) and the saturation (the dominance of the hue in the color). As
As the hue of a color changes, it moves around the square. At the center of the hue of a color changes, it moves around the square. At the center of the
the square, the saturation is zero, which means that the corresponding pixel square the saturation is zero, which means that the corresponding pixel has no
has no color. If you increase the amount of a specific color, while leaving color. If the amount of a specific color is increased (while leaving the other
the other colors unchanged, the saturation increases, and you move towards colors unchanged) the saturation increases, and the indicator moves towards
the edge of the square. the edge of the square.
@item color2 @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. are displayed.
@item waveform @item waveform
per row/column color component graph. In row mode graph in the left side represents Per row/column color component graph. In row mode, the graph on the left side
color component value 0 and right side represents value = 255. In column mode top represents color component value 0 and the right side represents value = 255.
side represents color component value = 0 and bottom side represents value = 255. In column mode, the top side represents color component value = 0 and bottom
side represents value = 255.
@end table @end table
Default value is @code{levels}. 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]. Allowed range is [0, 40].
@item step @item step
Set step for @code{waveform} mode. Smaller values are useful to find out how much Set step for @code{waveform} mode. Smaller values are useful to find out how
of same luminance values across input rows/columns are distributed. many values of the same luminance are distributed across input rows/columns.
Default value is @code{10}. Allowed range is [1, 255]. Default value is @code{10}. Allowed range is [1, 255].
@item waveform_mode @item waveform_mode
@ -5016,26 +5013,25 @@ It accepts the following values:
@table @samp @table @samp
@item parade @item parade
Display separate graph for the color components side by side in Display separate graph for the color components side by side in
@code{row} waveform mode or one below other in @code{column} waveform mode @code{row} waveform mode or one below the other in @code{column} waveform mode
for @code{waveform} histogram mode. For @code{levels} histogram mode for @code{waveform} histogram mode. For @code{levels} histogram mode,
per color component graphs are placed one bellow other. per color component graphs are placed below each other.
This display mode in @code{waveform} histogram mode makes it easy to spot Using this display mode in @code{waveform} histogram mode makes it easy to
color casts in the highlights and shadows of an image, by comparing the spot color casts in the highlights and shadows of an image, by comparing the
contours of the top and the bottom of each waveform. contours of the top and the bottom graphs of each waveform. Since whites,
Since whites, grays, and blacks are characterized by grays, and blacks are characterized by exactly equal amounts of red, green,
exactly equal amounts of red, green, and blue, neutral areas of the and blue, neutral areas of the picture should display three waveforms of
picture should display three waveforms of roughly equal width/height. roughly equal width/height. If not, the correction is easy to perform by
If not, the correction is easy to make by making adjustments to level the making level adjustments the three waveforms.
three waveforms.
@item overlay @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 that the graphs representing color components are superimposed directly
over one another. over one another.
This display mode in @code{waveform} histogram mode can make it easier to spot This display mode in @code{waveform} histogram mode makes it easier to spot
the relative differences or similarities in overlapping areas of the color relative differences or similarities in overlapping areas of the color
components that are supposed to be identical, such as neutral whites, grays, components that are supposed to be identical, such as neutral whites, grays,
or blacks. or blacks.
@end table @end table