Xerox WorkCentre Pro 412 Service Manual page 45

5-3-2 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: 300/400/600dpi CIS & CCD.
(6) Scanning Mode.
• color gray image: each 8 bits / RGB.
• mono gray image: 8 bits / pixel.
• binary image: 1 bit / pixel (for text/photo/mixed mode).
(7) Maximum scanning width: A3, 600dpi (8K effective pixels).
(8) Ideal MSLT (A4, 600/300dpi).
• color gray image: 3x5Kx80nsec = 1.2msec (7/28 CPM).
• mono gray image: 1x5Kx80nsec = 0.4msec (21/84 CPM).
• binary image: 1x5Kx80nsec = 0.4msec (21/84 CPM).
(9) A/D conversion depth: 12bits.
Pixel Processing Structure
• Minimum pixel processing time: 4 system clocks.
• High speed pipe-lined processing method.
(Shading correction, gamma correction, enlargement/reduction, and binarisation).
Shading Correction
(1) White shading correction support for each R/G/B.
(2) White shading data memory: 3x8Kx12bits = 288Kbits → 384Kbits (external).
(3) Black shading data memory: 3x8Kx12bits = 288Kbits → 384Kbits (external).
Gamma Correction
(1) Independent gamma table for each RGB component.
(2) Gamma table data memory: 3x1Kx8bits = 24Kbits (internal).
Binarisation (mono)
(1) 256 Gray's halftone representation for photo document: 3x5 EDF (Error DifFusion) method proposed by
Stucki.
(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: 25 to 800% by 1% unit.
• Vertical direction: 25 to 100% by 1% unit.
(2) Scaling data memory: 2x8Kx8bits = 128Kbits (internal).
WorkCentre Pro 412
Launch Issue
August 2001
Circuit Description
5-19