Samsung S5PC110 Manual page 1603

S5PC110_UM
9.2.2.17 MIXER_COLOR_SPACE_CONVERSION_COEF_Y Register (MIXER_CM_COEFF_Y, R/W, Address
= 0xF920 0080)
MIXER_CM_COEFF_Y
Reserved
WIDE_SEL
REG_COEFF_00
REG_COEFF_10
REG_COEFF_20
NOTE: RGB to YCbCr Conversion Equations
RGB data with 16-235 range
Y601 = 0.299R + 0.587G + 0.114B
Cb = -0.172R – 0.339G + 0.511B + 128
Cr = 0.511R – 0.428G – 0.083B + 128
RGB data with 0-255 range
Y601 = 0.257R + 0.504G + 0.098B + 16
Cb = -0.148R – 0.291G + 0.439B + 128
Cr = 0.439R – 0.368G – 0.071B + 128
Fraction Number (Exaple, 1bit is Signed bit and 9bits are Fraction Bit)
0.098 = 0.5* '0' + 0.25* '0' + 0.125* '0' + 0.0625* '1' + 0.03125* '1' + 0.015625* '0' + 0.0078125* '0' +
0.00390625* '1' + 0.001953125* '0' = 0(signed bit) 0 0 0 1 1 0 0 1 0 = 0x032
-0.148 -> First of all, let's think about 0.148
0. 148 = 0.5* '0' + 0.25* '0' + 0.125* '1' + 0.0625* '0' + 0.03125* '0' + 0.015625* '1' + 0.0078125* '0' +
0.00390625* '1' + 0.001953125* '1' = 0(signed bit) 0 0 1 0 0 1 0 1 1 = 10'b0001001011
Now, to change the number from 0.148 to -0.148, we have to derive 2's compliment of 0.148
10'b 0 0 0 1 0 0 1 0 1 1 -> 10'b 1 1 1 0 1 1 0 1 0 0 (bitwise invert) + 1 = 10'b 1 1 1 0 1 1 0 1 0 1 = 0x3B5
Bit
[31] Reserved, read as zero, do not modify
[30] 0 = Narrow
1 = Wide
[29:20] Scaled color space conversion coefficient (C
[29]: Sign-bit
[28:20]: Fractional bit
(Default and Recommended value : 0.257 in
decimal)
Scaled color space conversion coefficient (C
[19:10]
[19]: Sign-bit
[18:10]: Fractional bit
(Default and Recommended value : 0.504 in
decimal)
Scaled color space conversion coefficient (C
[9:0]
[9]: Sign-bit
[8:0]: Fractional bit
(Default and Recommended value : 0.098 in
decimal)
Description
Y709 = 0.213R + 0.715G + 0.072B
Cb = -0.117R – 0.394G + 0.511B + 128
Cr = 0.511R – 0.464G – 0.047B + 128
Y709 = 0.183R + 0.614G + 0.062B + 16
Cb = -0.101R - 0.338G + 0.439B + 128
Cr = 0.439 – 0.399G – 0.040B + 128
9 8BMIXER
Initial State
0
0x84
00).
0x102
10).
0x32
20).
9-23