Samsung ML-920 Service Manual page 154

CIRCUIT DESCRIPTION
3-3-2 KEY FEATURES
Overview
(1) 0.5µm C-MOS process(TLM), 208-PIN QFP, STD85 library
(2) Frequency : 50 MHz
(3) On-Chip oscillator
(4) Method : Raster scanning method
(5) Image Sauce : 300 dpi CIS
(6) Scanning Mode
• color gray image: each 8 bits / RGB
• mono gray image
• binary image
(7) Maximum scanning width : A4, 300 dpi
(8) A/D conversion depth : 12bits
Pixel processing structure
• Minimum pixel processing time : 4 system clocks
• High speed pipelined processing method
(Shading correction, Gamma correction, Enlargement/Reducement, and Binarization)
Shading Correction
(1) White shading correction support for each R/G/B
(2) White shading data memory : 3x8Kx12bits = 288Kbits
(3) Black shading data memory : 3x8Kx12bits = 288Kbits
Gamma Correction
(1) Independent Gamma table for each RGB component
(2) Gamma table data memory : 3x1Kx8bits = 24Kbits (internal)
Binarization (mono)
(1) 256 Gray's halftone representation for Photo document : 3x5 EDF(Error DifFusion) method proposed by Stuck.
(2) LAT(Local Adaptive Thresholding) for Text document :
• use of 5x5 LOCAL WINDOW (TIP ALGORITHM)
• ABC(Automatic Background Control) :Tmin Automatic change
(3) Mixed mode processing for text/photo mixed document
(4) EDF data memory : 2x4Kx16bits = 128Kbits (internal)
(5) LAT data memory : 4x4Kx16bits = 256Kbits (external)
Scaling of input image
(1) Scaling factor
• Horizontal direction
• Vertical direction : 25 ~ 100% by 1% unit
(2) Scaling data memory : 2x8Kx8bits = 128Kbits (internal)
Repair Manual
3-24
: 8 bits / pixel
: 1 bit / pixel (for text/photo/mixed mode)
: 25 ~ 800% by 1% unit
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384Kbits (external)
384Kbits (external)
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