gl845 Genesys Logic, gl845 Datasheet - Page 85

• Manufacturer Part Number: gl845
• Description: High Speed Usb 2.0 2-in-1 Scanner Controller With Adf
• Manufacturer: Genesys Logic

with 1 pixel time resolution.
8 Support Analog Front End Timing
GL845 supports external 16 bits front-end.
Wolfson: WM1645
Analog device: AD9826, …etc.
9 Image Type
A. Supports color, gray and line art scanning.
B. Supports color filters options (R, G or B channels) in gray or line art scanning.
C. Supports true gray with programmable R, G and B weightings.
10 Bits Depth
16*3 bits color, 16 bits gray level and 1 bit line art (Black & White).
Image data type: 16 bits, 8 bits and 1 bit.
11 Shading & Correction
a. White Shading & Dark Shading:
b. Gamma Correction:
12 Threshold Setting for Line-Art
Threshold can be programmed by S/W.
Range: 0 ~ 255 adjustable.
The threshold with hysteresis characteristic is for reducing image noise.
©2000-2007 Genesys Logic Inc. - All rights reserved.
White shading and dark shading are pixel-by-pixel corrections with 16-bit solution and can be enabled or
disabled by S/W. The white shading curve is calculated by S/W.
Data arrangement: three line in mode: dark R1, white R1, dark G1, white G1, dark B1, white B1,
White shading formula:
White shading formula:
For example: Target = 3FFFH, Wn = 2FFFH, Dn = 0040H and 8 times system operation
16-bit GAMMA correction table is programmed by S/W.
Range: 0 ~ 64k (16 bits) input mapping to 0 ~ 255 (8 bits) output.
Style: increment or decrement gamma curve
Note: 16 bits image data will be mapped to 8 bits data by gamma table. Designer can get 16 bit image data
BWHI
BWLOW
by disabling gamma table.
GL845 High Speed USB2.0 2-in-1 Scanner Controller With ADF
then White Gain = 2000H * 3FFFH / (2FFFH-0040H) = 2AE4H (1.34033 times)
a
one line in mode: dark R1, white R1, dark R2, white R2, dark R3, white R3…
b
2000H * Target / (Wn-Dn) = White Gain data ----- for 8 times system
4000H * Target / (Wn-Dn) = White Gain data ----- for 4 times system
c
dark R2, white R2, dark G2, white G2, dark B2, white B2,
dark R3, white R3, dark G3, white G3, dark B3, white B3,
dark G1, white G1, dark G2, white G2, dark G3, white G3…
dark B1, white B1, dark B2, white B2, dark B3, white B3…
d
e
f
g
h
i
hysteresis width
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