Lossless JPEG Encoder Core
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The LJPEG-E conforms to the spatial (sequential) lossless encoding mode (SOF3) of the ISO/IEC 10918-1 standard (CCITT T81 recommendation). Rather than the Discrete Cosine Transform (DCT) functions used for lossy JPEG compression - which can introduce round-off errors - the LJPEG-E employs a predictor function as described in the specification. It thus encodes and compresses images with no information loss, and requires a significantly smaller physical implementation. Evaluation designs show that the core requires just 21K gates in an ASIC. Its heavily optimized architecture also enables very high performance, reaching 500 MSamples/sec on 90nm process (under typical process and operating conditions). The LJPEG-E is a fully synchronous, strictly positive-edge design with no internal three-state buffers. Comprehensive documentation and a complete verification environment - including a bit-accurate model - help designers integrate and verify the core.
Features
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- Conforms to the spatial (sequential) lossless encoding mode (SOF3) of the ISO/IEC 10918-1 standard (CCITT T81 recommendation).
- Standalone operation.
- Pixel samples input.
- Standalone ISO/IEC 10918-1 JPEG stream output.
- Easily programmable through standard JPEG markers stream.
- Programmable image dimensions.
- Full range sample precision support (2 to 16 bits per sample)
- Up to four stream programmable Huffman tables.
- Programmable Restart Interval.
- Programmable Point Transform function.
- Programmable APPn and COM markers.
- Programming errors catch-up features.
- Compact, high-performance architecture.
- 21K gates achieving 500 MSamples/sec (90nm ASIC) under typical process and operating conditions.
- Also fits inexpensive FPGAs (see FPGA version datasheets)
- Robust and simple to use
- General purpose, fully stallable, streaming I/O interfaces.
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Block Diagram
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