MB86296 Datasheet, PDF (82/352 Pages) Fujitsu Component Limited. – PCI Graphics Controller Specification

FUJITSU LIMITED PRELIMINARY AND CONFIDENTIAL
7.7 Programmable YCbCr/RGB conversion for L1-layer display
L1-layer can display video data in YCbCr format but RGB conversion coefficients are hard-wired and
fixed about previous products. Coral-PA can program RGB conversion coefficients by registers.
YCbCr data is converted by following expression.
R = a₁₁*Y + a₁₂*(Cb− 128) + a₁₃*(Cr−128) + b₁
G = a₂₁*Y + a₂₂*(Cb− 128) + a₂₃*(Cr−128) + b₂
B = a₃₁*Y + a₃₂*(Cb−128) + a₃₃*(Cr−128) + b₃
a_ij ---- 11bit signed real ( lower 8bit is fraction, two's complement )
b_i ----- 9bit signed integer ( two's complement )
It is represended by matrix operation.
R
Y
G _{= A} Cb-128 _{+ b}
B
Cr-128
A ^where
a11 a12 a13
= ^a21 ^a22 ^a23
a31 a32 a33
,
b=
b1
b2
b3
These parameters are set on registers shown bellow.
L1YCR0 (a₁₁,a₁₂), L1YCR1(a₁₃,b₁)
L1YCG0 (a₂₁,a₂₂), L1YCG1(a₂₃,b₂)
L1YCB0 (a₃₁,a₃₂), L1YCB1(a₃₃,b₃)
Same conversion with previous products is applied by initial values of these registers after reset.
The register values just after reset is as follow.
a₁₁ = 0x12b (299/256) , a₁₂ = 0x0, a₁₃ = 0x198 (408/256)
a₂₁ = 0x12b (299/256), a₂₂ = 0x79c (-100/256), a₂₃ = 0x72f (-206/256)
a₃₁ = 0x12b (299/256), a₃₂ = 0x204 (516/256), a₃₃ = 0x0
b₁= b₂= b₃= 0x1f0 (-16)
It is possible to control brightness, contrast, hue , color saturation by change these parameters.
Addition of a constant value into b means inclease of brightness.
Multiplication of a constant scalar value greater than one into A means increase of contrast.
Two dimentional rotation of Cb-128 and Cr-128 means change of hue.
Color saturation is intensity of color, relative to Y-component.
New coefficients including these changes can be got by following expression.
MB86296S<Coral-PA>
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Specification Manual Rev0.1