Phytec eGrabber-4plus, Hardware Manual

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eGrabber-4plus
162 
PHYTEC Meßtechnik GmbH 2004 L-608e_4
Under the DOS operating system, the user must reserve a space in the
computer’s RAM for storing images . A pointer that indicates the
beginning of the reserved memory space must also be handed over.
The control of parameters for resolution scaling and positioning is
equal to the procedure in the windows.
Now the format of an image to be digitized, is exactly defined. The
Grabber must now be instructed where and how to store the data of
the image in the memory.
Therefore it is required to reserve a region in the main memory of
sufficient size.
This is achieved by utilization of the well known instructions for the
allocation of memory (for example malloc(...)).
How much memory will be used? This will be calculated from the size
of the image (number of pixels) and the required number of Bytes per
pixel (color resolution):
Memory requirements per field = hsize
.
vsize
.
pixel size [Byte]
The value pixel size can be depicted from Table 12.
For the format YUV2 and BtYUV it must be considered, that 2 or
8 pixels are combined and that the resolution of the image is selected
correspondingly. The value calculated for the required region of
memory is valid for one field (even or odd).
Format pixel size [Byte]
RGB32 4
RGB24 3
RGB16, RGB15 2
YUY2 4 Byte per 2 Pixel
BtYUV 12 Byte for 8 Pixel
Y8 1
Table 13: Memory Requirements for a Pixel in the Single Mode