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MN86074

Image Processing LSI

Panasonic Corporation 

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.

Features

Image processing that yields top image quality

• Infinite shading for all pixels using a division technique

• Error dispersion processing that reproduces halftone

images with 64-gradation

User-programmable gamma curve

• Two dimensional MTF correction

• 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

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 –12 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

• Infinite shading for all pixels using a division

technique

Distortion correction levels relative to A/D

converter's dynamic range

0 – 75%................... 6-bit precision

75 – 87.5%............... 5-bit precision

87.5 – 93.8%............ 4-bit precision

MTF correction:

• Laplacian transforms (processing for text images)

Reference to five pixels

Halftone processing

• Error dispersion processing: Reproduction of 64-

gradation using 6-bit processing

Gamma correction:

• User-definable by loading a conversion curve

Conversion levels: 6 bits to 6

Binary coded:

• Fixed slice

Slice level: User-specified 5-bit value

Reduction in primary scanning direction:

• 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

• Black pixel preservation (for reduction in primary

scanning direction)

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