Benefits

Ultimate performance-bitonal image compression device

Unparalleled throughput-Processes 600 dpi documents in less than 150 milliseconds

Highly integrated-Internal SRAM and Phase-Locked Loop (PLL)

Improved I/O-32-bit interface

Multi-standard support-ITU G3, G4 and JBIG

Improved system performance-Enhanced multi-tasking

High Throughput

The PM-22 can handle letter-sized 300 dpi documents in less than 45 milliseconds and 600 dpi documents in less than 150 milliseconds. With a maximum clock speed of 75 MHz, the PM-22 delivers a typical throughput of 225 Mpixels/second for ITU G3 and G4 data. The worst-case throughput for any compression/decompression standard is 75 Mpixels/second.

Integrated SRAM and PLL

To maximize cost-effectiveness, the PM-22 has integrated SRAM and Phase-Locked Loop (PLL). The PM-22’s 16 KB of integrated SRAM reduces overall system cost. Its integrated PLL enables the PM-22 to generate its main internal clock frequency from a lower-frequency signal for reduced emissions and simplified board design.

32-bit I/O Interface

The PM-22 features a new interface mode that enables it to be connected directly to 32-bit system busses. It allows use of a 32-bit host port for input, output or both. An 8-bit or 16-bit peripheral port is also provided. Input and output data bit and byte reordering functions have been expanded in the PM-22 to include word-swapping.

JBIG Compression

JBIG offers compression ratios up to four times higher than with two-dimensional ITU Group 4 encoding methods. This improvement significantly increases system performance and reduces image storage and transmission costs.

Enhanced Multi-Tasking

Like previous PM-2x Codecs, the PM-22 fully supports multitasking for interrupt-driven image processing in multi-function peripherals. In addition, multi-tasking has been optimized on the PM-22 to reduce host processor interrupts during JBIG operations.

PM-22 Capabilities

The PM-22 enables the following combinations of operations to be performed on the data stream during one pass through the device:

Decompress, scale, and clip the resulting bitonal data

Decompress, scale to gray, and clip the resulting data

Decompress, clip and rotate to any multiple of 90 degrees

Clip and compress bitonal input

Scale factors for pass-through or decompression operations range from 1:256 to 255:1 in increments of 1/256. The PM-22 supports any combination of bit and byte ordering on both input and output ports. In addition, the PM-22 supports "fast" padding for improved output formatting operations.

The Role of Multi-Tasking

Effective multi-tasking will increase processor efficiency by reducing the overhead involved in multiple simultaneous compression/decompression processes. The PM-22 is capable of halting a process at the end of any line and cleanly restarting. When the processor is halted, the internal state can be read and stored. The PM-22 can then be reconfigured and restarted, either with a process that has been suspended or with an entirely new process.

Design Considerations

The PM-22 requires little in the way of external support chips.
The PM-22 includes 16 KB of internal SRAM, sufficient to supportmost common coding or decoding operations. Rotation, scaling and multi-tasking operations may require an external SRAM (8 KB minimum; supports up to 128 KB), which serves as a local buffer during processing operations. Multi-tasking systems are able to use either internal or external SRAM for any task that fits into available memory.

Key Features

75 MHz clock speed for high throughput

Integrated SRAM (16 KB) and Phase-Locked Loop (PLL)

32-bit I/O interface mode

Support for ITU G3, G4 and JBIG bitonal image data formats

Enhanced multi-tasking

3.3 Volt power supply

16 KB internal SRAM

High-speed rotation assist function, concurrent with decompression

Flexible I/O modes include Burst, FIFO, and Full Duplex DMA operation

Programmable output palette

Large image size capacity–handles up to 64 K pixels per line, up to 64 K lines

Programmable bit, byte and word ordering on input and output

PM-22 Specifications

Storage Formats Supported

ITU Group 3 1D (Modified Huffman coding)

ITU Group 3 2D (Modified READ coding, programmable K-factor)

ITU Group 4 2 D (Modified Modified READ (MMR) coding)

IBM MMR coding

TIFF Type 2

JBIG (ISO IS 11544 compliant) Single progression sequential, Adaptive pixel, Typical prediction, 2 or 3 Line template, Variable stripe size

Electrical Specification

3.3 Volt power supply

5 Volt tolerant I/O (TTL-compatible I/O)

Designed and fabricated in 0.35 micron standard cell technology

Available in industry-standard 28mm 160 PQFP package

Also available in lead-free “green” packaging