Atmel Evaluation Kit AT91SAM9X35-EK AT91SAM9X35-EK Data Sheet

1107

SAM9X35 [DATASHEET]

11055E–ATARM–10-Mar-2014

Color keying involves a method of bit-block image transfer (Blit). This entails blitting one image onto another where not all
the pixels are copied. Blitting usually involves two bitmaps, a source bitmap and a destination bitmap. A raster operation
(ROP) is performed to define whether the iterated color or the overlay color is to be visible or not.

If the masked overlay color matches the color key then the iterated color is selected. Source Color Keying is activated
using the following configuration.



Select the Overlay to Blit 



Set DSTKEY field to zero



Activate Color Keying setting CRKEY field to 1



Program Color Key writing RKEY, GKEY and BKEY fields



Program Color Mask writing RKEY, GKEY and BKEY fields

When the Mask register is set to zero, the comparison is disabled and the raster operation is activated.

If the iterated masked color matches the color key then the overlay color is selected. Destination Color Keying is
activated using the following configuration:



Select the Overlay to Blit



Set DSTKEY field to one



Activate Color Keying setting CRKEY field to 1



Program Color Key writing RKEY, GKEY and BKEY fields



Program Color Mask writing RKEY, GKEY and BKEY fields

When the Mask register is set to zero, the comparison is disabled and the raster operation is activated.

1 bpp

32

Not supported

Supported

2 bpp

16

Not supported

Supported

4bpp

8

Not supported

Supported

8 bpp

4

Not supported

Supported