When an application sets a bit map, the bits are specified as indexes into the color table supplied with the bit map. The presentation driver allocates its own copy of the bit map.

The driver-level pels contain indexes to the nearest color in the default physical palette.

Note: This means that GreGetBitMapBits does not necessarily return the same bit map that the application set. Information may be lost if the bit map is taken to a less color-capable system and then brought back to the (more capable) system on which it was created.

However, an application can select a palette into a memory DC. This causes the color table and the bit-map bits to change to the nearest mapping to the new palette. Calls to GreRealizePalette are not performed on memory DCs. The palette takes effect as soon as it is selected.

The presentation driver is expected to perform any allocation and data structure needed for a subsequent GreDeviceResizePalette to succeed.