3.1.9 RDP 6.0 Bitmap Compression

RDP 6.0 Bitmap Compression is used when the RDP session color depth is 32 bits per pixel (bpp) and the bitmap of interest is either 24 bpp (RGB with no alpha channel) or 32 bpp (RGB with an alpha channel). The capability of a server to encode and a client to decode with RDP 6.0 Bitmap Compression is advertised in the Bitmap Capability Set (see [MS-RDPBCGR] section 2.2.7.1.2).

The main focus of RDP 6.0 Bitmap Compression is not to compress the bitmap as a single opaque block of binary data. Instead it manipulates each of the color layers as separate planes and attempts to compress them individually using a collection of compression techniques. These techniques attempt to leverage any redundancy in the color representation of the bitmaps and can additionally be followed by a simple scan-line run-length compressor if it can further compress the planes.

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