Phytec eGrabber-4plus, Руководство по оборудованию

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Driver Software

PHYTEC Meßtechnik GmbH 2004 L-608e_4
125
After size and resolution of the image are defined, the data format has
to be selected. The parameter Colformat describes the format, a pixel
has to be stored in the memory of the PC, and how many Bytes are
occupied by one pixel.
The format is determined by the application. In general three formats
can be distinguished, which again can be separated in different
formats. Figure 52 shows how pixels can be stored in the memory for
different formats.
l
RGB : The information for brightness is divided in three color
channels: red, green and blue and are stored separately. This is a
standard, which is used to process and handle color information.
é
For RGB32 32-bit, a double word per pixel is utilized.
The lowest Byte of each double word contains the
information for the blue color (8-bit), the second Byte
the green and the third Byte the red color information.
The highest Byte contains no information and is used
only to obtain a whole double word for one pixel:
After each double word a new pixel begins
(see Figure 52 that related information have same
hatching).
The alignment of double words might have the
advantage, that fast access commands could be used.
The number of colors is 16 million
(2
38
= 16.777
•
10
6
).
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RGB24 delivers the same information as RGB32, but
does not contain the stuffing Byte. The image has the
same resolution but occupies a smaller area of the
memory.
é
RGB16 has a reduced resolution of the color. This for-
mat requires five bit for the blue and red channel, and
the green channel has 6-bits. The color depth is 65.536
(
2 2 2 65536
5 5 6
⋅ ⋅ =
). One pixel needs 16-bits = 1 word.
In Figure 52 the partitioning into three color channels
of the word is depicted. The color information is
arranged „left justified“; the lower bits are omitted, so
that the color depth is reduced.