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3.. Version 1.1 or any later version published by the Free Software
4.. Foundation, with no Invariant Sections, no Front-Cover Texts
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6.. Documentation/userspace-api/media/fdl-appendix.rst.
7..
8.. TODO: replace it to GFDL-1.1-or-later WITH no-invariant-sections
9
10************
11Introduction
12************
13
14Some video capture devices can sample a subsection of a picture and
15shrink or enlarge it to an image of arbitrary size. Next, the devices
16can insert the image into larger one. Some video output devices can crop
17part of an input image, scale it up or down and insert it at an
18arbitrary scan line and horizontal offset into a video signal. We call
19these abilities cropping, scaling and composing.
20
21On a video *capture* device the source is a video signal, and the
22cropping target determine the area actually sampled. The sink is an
23image stored in a memory buffer. The composing area specifies which part
24of the buffer is actually written to by the hardware.
25
26On a video *output* device the source is an image in a memory buffer,
27and the cropping target is a part of an image to be shown on a display.
28The sink is the display or the graphics screen. The application may
29select the part of display where the image should be displayed. The size
30and position of such a window is controlled by the compose target.
31
32Rectangles for all cropping and composing targets are defined even if
33the device does supports neither cropping nor composing. Their size and
34position will be fixed in such a case. If the device does not support
35scaling then the cropping and composing rectangles have the same size.
36