Brightness, Contrast, Color, and Levels Curve
   
VirgaVideo allows you to adjust the brightness, contrast, and color of your videos
and pictures. To do this, right click an object and
then select Edit...Levels.
 
The levels curve (see picture below) is shown, and you can fine tune the colors until your pictures
and videos look good.
To adjust the curve, click on the graph to
create a control point and then move it by dragging. Moving a control point above the diagonal line will make
the picture brighter, and moving it below the diagonal line will
make the picture darker (see examples below). Right clicking a
control point will delete it.
Moving a control point on the left side of the graph will adjust the dark
portions of the picture, while moving a control point on the right side of the graph
will adjust the bright portions of the picture (see more examples
below).
In many cases, you will either want to brighten (or darken) the
mid-tones of the picture with a gentle curve as shown in the example
at the top of this page.
Channel: After you have adjusted the general brightness
and contrast with All channels selected, you might find
that the colors are not correct (e.g. the picture might be tinted
red). To adjust only one primary color at a time, select the
Red, Green, or Blue channel, and move the
control points. In the example at the top of this page, the
image was too red after adjusting only the All channel.
This was corrected by adjusting the red channel to be darker than
the blue and green channels.
Copy/Paste/Reset: If you have spent some time creating a curve
you like, you can copy it to the clipboard by clicking the Copy
button. Then select as many objects as you want, and click the
Paste button. The curve will be copied to all selected objects.
The Reset button will reset the levels curve back to normal.
Undo: All changes you make are saved, and you can undo
them by pressing CTRL-Z. To redo the change, press
CTRL-Y.
Level Adjustment Examples
In the example below, I have increased the overall brightness of
the picture by adjusting the mid-tones. The control point is
near the middle of the horizontal axis (hence, we are adjusting the
mid-tones) and above the diagonal line (hence, we are brightening
them). Note that I am adjusting only the All
channel, which will adjust the red, green, and blue channels at
the same time.
  
We can increase the contrast of the picture by darkening the dark
sections, while at the same time brightening the brighter sections.
In the example below, I have added a new control point. This
new control point is near the left side of the horizontal axis
(hence, we are adjusting the darker sections of the picture) and
below the diagonal line (hence, we are making them darker).
 
When I adjusted the brightness and contrast, I lost some of the
blueness of the sky. This can be fixed by clicking the Red, Blue,
or Green channel, and adjusting each color individually.
In this example, I have increased the bright portions of the blue
channel, while decreasing the red and green channels. This
makes the brighter parts of the picture more blue without affecting
the darker areas.
 
And, you can do some really strange things if you want...
 
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