Specifications

64 Issue Date: 2004/11/05 │ CONFIDENTIAL

CL765 │ Camera Application Processor

Datasheet

│ Doc. #: CLQP-DS-743

4.13.1.3. 565-RGB

For 565-RGB format, R, G and B component of each pixel are constructed by bit

expansion logic operation as shown in Figure 4-20. For the format alpha value of

each pixel is not available. Instead, the value of REG_0x18[7:4] is used as alpha

value for all pixels.

α[3:0] = REG_0x18[7:4]

R[5:0] = {bit[15:11], bit[15]}

G[5:0] = bit[10:5]

B[5:0] = {bit[4:0], bit[4]}

b15

b14

b13

b12

b11

b10

565- RGB color

5- bit to 6 - bit

expansion

b[4:0] b[4] b[10:5] b[15:11] b[15]

5- bit to 6 - bit

expansion

α[3:0]

[7:4]

RGB18

Figure 4-18. The Bit Expansion for 565-RGB Color

4.13.1.4. Chroma-keying

Chroma-keying is one of methods compositing two source images into one. The

function checks if the current pixel of foreground bitmap matches to the pre-

defined color (the value of REG_0x19) and replaces it to pixel from background

bitmap (Figure 4-21). For SARA, besides alpha-blending, chroma-keying is also

provided. For 8bit-indexed bitmap, the pixel data after CLUT is used to compare

to REG19, while pixel data from source bitmap is used for 4444-αRGB and 565-

RGB format.