IMPORT/EXPORT FILTERING

PCX is an obsolete but still widely accepted format for pixel image data files. It uses an ineffective RLE compression algorithm that works well only on 'cartoon' images. With many real-life images, the compressed file will actually be larger than the raw data file before compression.

Any PCX image can attached to a CIRCAD data file. Once attached, the image will zoom and pan along with the other placed ojbects.

The encoding scheme is relatively simple consisting of a file header and a compressed raster pixel image. The pixel image may optionally be followed by a RGB color translation table. Color images are automatically translated to greyscale by the file import module.

BYTES  DESCRIPTION
00     File ID (must be 0Ah).
01     Version number (must be 05h).
02     Compression code (must be 01h).
03     Bits per pixel (must be 1 or 8).
04-05  Minimum X pixel (must be 0000h).
06-07  Minimum Y pixel (must be 0000h).
08-09  Maximum X pixel (width-1).
0A-0B  Maximum Y pixel (height-1).
0C-0D  Horizontal DPI (dots per inch).
0E-0F  Vertical DPI (dots per inch).
10-3F  Colormap (ignored).
40     Unused (ignored).
41     Color plane count (must be 1 or 3).
42-43  Horizontal line width (in bytes).
44-45  Color/BW code (ignored).
46-7F  Unused (ignored).
80-??  Pixel image data (compressed).

CIRCAD's transparent import filtering allows you to read a PCX
file by simply selecting the desired file when using the
Open File function.

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