For Communications Equipment
MN86074
Image Processing LSI
Overview
The MN86074 boosts image quality by applying various
image processing techniques to the analog signal from
an image sensor. Features include correction of laser
printer dot spreading at the pixel level, processing to
enhance the compression ratio, reproduction of halftone
images with 64-gradation, two-dimensional MTF
correction using moire suppression, and infinite shading
for all pixels using a division technique. These combine
to yield top image reproduction quality.
Gain control: Analog control using an external
operational amplifier and the built-in field effect
transistor (FET)
An external resistor determines the follow-up range.
(The standard range is from +6 dB to 鈥?2 dB.)
Built-in circuits: Gain control circuit + FET
A/D converter: Half flash converter
Number of bits: 8
Conversion speed: 0.1 to 1.5 MHz
Shading correction
鈥?Infinite shading for all pixels using a division
technique
Distortion correction levels relative to A/D
converter's dynamic range
0 鈥?75%................... 6-bit precision
75 鈥?87.5%............... 5-bit precision
87.5 鈥?93.8%............ 4-bit precision
MTF correction:
鈥?Laplacian transforms (processing for text images)
Reference to five pixels
Halftone processing
鈥?Error dispersion processing: Reproduction of 64-
gradation using 6-bit processing
Gamma correction:
鈥?User-definable by loading a conversion curve
Conversion levels: 6 bits to 6
Binary coded:
鈥?Fixed slice
Slice level: User-specified 5-bit value
Reduction in primary scanning direction:
鈥?Decimation with image clock or line enable
Reduction ratio in primary scanning direction:
Binary coded 0.78% to 100%
Halftone processing: 50 to 100%
(in 0.78% increments)
Reduction correction in primary scanning direction
鈥?Black pixel preservation (for reduction in primary
scanning direction)
Features
Image processing that yields top image quality
鈥?Infinite shading for all pixels using a division technique
鈥?Error dispersion processing that reproduces halftone
images with 64-gradation
User-programmable gamma curve
鈥?Two dimensional MTF correction
鈥?High-quality reduction with a user-specified scaling
factor
Preserves halftone gradation
Preserves fine black lines for text
High-speed processing requiring only 2 ms per line
for an A3 page at 200 dpi
Built-in analog processing circuits: offset correction
circuit, gain correction circuit, and 8-bit analog-to-
digital converter
Drive signal generator for CCDs, CISs, and other
image sensors
Brief Specifications
Image processing speed: 0.1 to 1.5 million pixels per
second
Pixels per line: max. 8192 pixels-blanking pixels
1-line interval: max. 8192 pixels
Offset correction: negative feedback to preamplifier
The chip controls the feedback voltage using A/D con-
version data from black pixel runs.
Built-in circuits: Feedback voltage control circuit +
source follower circuit
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