Revision 1.3

Mar.22 2001

-15-

GL646USB

Internal white shading by pixel (16 bits resolution) and dark shading by pixel (16 bits resolution) can be enabled or

disabled By S/W. The white shading curve is calculated by S/W.

Data arrangement: Normal mode: dark R1,white R1,dark G1,white G1,dark B1,white B1,

dark R2,white R2,dark G2,white G2,dark B2,white B2,

dark R3,white R3,dark G3,white G3,dark B3,white B3,……

Fast mode: dark R1,white data R1,dark R2,white R2,dark R3, white R3…

dark G1,white data G1,dark G2,white G2,dark G3,white G3…

dark B1,white data B1,dark B2,white B2,dark B3,white B3…

White shading formula :

2000H x Target / (Wn-Dn) = White Gain data ----- for 8 times system

White shading formula :

4000H x Target / (Wn-Dn) = White Gain data ----- for 4 times system

For example : Target = 3FFFH

Wn = 2FFFH

Dn = 0040H

and 8 times system operation

then

White Gain = 2000H x 3FFFH / (2FFFH-0040H) = 2AE4H (1.34033 times)

b. Correction :

GAMMA correction table by S/W calculation. The resolution is 12 or 14 bits gamma table.

Range: 0 to 64k (16 bits) input mapping to 0 to 4k (12 bits) output ;

0 to 64k (16 bits) input mapping to 0 to 16k (14 bits)output;

0 to 64k (16 bits) input mapping to 0 to 255 (8 bits) output ;

0 to 64k (16 bits) input mapping to 0 to 255 (8 bits) output;

6.12. Threshold Level Setting

Can be programmed by S/W.

Range: 0 to 255 can be adjusted by one increment.

The threshold with bandwidth in order to reduce image noise.

6.13. Exposure Time Adjustable

Maximum: 512k pixels time (about 524 ms/line)

Adjustment step: 1 pixel time.

For Transparency scan, the exposure time can up to 524 ms.

6.14. To Control RGB Exposure Time Separately

bandwidth

a,b,c,g : are black pixels

d,e,f,h,i : are white pixels

BWHI

BWLOW

a

b

c

d

e

f

g

h

i