unsigned FreeImage_GetRedMask(FIBITMAP *dib);

Returns the red bitmask for the bitmap. If the bitmap is palletised 0 is returned.

unsigned FreeImage_GetGreenMask(FIBITMAP *dib);

Returns the green bitmask for the bitmap. If the bitmap is palletised 0 is returned.

unsigned FreeImage_GetBlueMask(FIBITMAP *dib);

Returns the blue bitmask for the bitmap. If the bitmap is palletised 0 is returned.

BYTE FreeImage_GetTransparencyCount(FIBITMAP *dib);

Returns the number of transparent colours stored into the transparency colour table of the given bitmap. Every palletised bitmap includes a transparency table containing up to 256 alpha values.

BYTE *FreeImage_GetTransparencyTable(FIBITMAP *dib);

Returns the transparency table assigned to this bitmap. If the bitmap doesn't contain a transparency table NULL is returned.

void FreeImage_SetTransparencyTable(FIBITMAP *dib, BYTE *table, BYTE count);

Assigns a new transparency table to the bitmap. A transparency table consists of up to 256 bytes in an array, where a value of 0xFF in that table stands for completely opaque and 0x00 stands for completely invisible. The transparency table is used in TrollTech Qt to draw transparent bitmaps on a widget.