Real Colour Grab

This option provides a method of acquiring full colour images using the grey scale DT-2861 or DT-2862. The primary limitation is the low colour resolution: 3 bits for the red (0, 3 & 6) and green (1, 4 & 7) components, and 2 bits for blue (2 & 5). Hence this option is of use only when very simple images are required.

To utilise this option, a DT-2859 video multiplexer must be installed with the red, green and blue components of an image made available on inputs 1, 2 and 3 (respectively). Typically these components will be from an external PAL, NTSC or Y/C to RGB decoder.

The image is acquired in three separate operations spanning 10 video fields (5 frames). It is therefore necessary for the image to be relatively static during this operation. The components are acquired in the order red, green then blue.

Once acquisition is complete, the current output look up table will be changed to table 16 (<G>) which is specifically designed for viewing these images.

Grab real colour image to which buffer ?

The colour image may be acquired to any valid buffer. The selected buffer will be made the current output buffer. Extended memory buffers are vectored through buffer 0.

Press any key to grab frame. Note there will be a small delay before complete aquisition.

Pressing any key (other than <escape>) will start the acquisition process. There will be a delay of approximately four fields (two frames) before the red component is acquired. The green and blue fields will be acquired in turn, starting at intervals of four fields (two frames). It is necessary for the image to be relatively static over the ten fields (five frames) between the beginning of the red acquisition and the end of the blue acquisition.

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DigImage User Documentation

Stuart Dalziel, last page update: 19 February 1996