Samsung S3C2451X User Manual page 431

S3C2451X RISC MICROPROCESSOR
Per-pixel alpha blending: ALPHA (given by the source image, from 0 to 255)
[Alpha Blending]
data = ( source * (ALPHA+1) + destination * (255-ALPHA) ) >> 8
[Fading]
data = ((source * (ALPHA+1) ) >> 8 ) + fading offset
Related Registers
ROP_REG
ALPHA_REG
Alpha blending configurations: alpha blending disable/enable, per-pixel alpha
blending disable/enable, fading disable/enable.
Alpha value and fading value.
Preliminary product information describe products that are in development,
for which full characterization data and associated errata are not yet available.
Specifications and information herein are subject to change without notice.
2D
19-11