DLI is a state-of-the-art lossy image compression system. It compresses more than
any commercial or research codec, holding the records for PSNR and MS-SSIM.
The current version of DLI includes 3 codecs, 2 are computation intensive with one
optimizing for PSNR and the other visual quality. The third is a "high speed" version
of the visual codec that is fast enough for practical use.
DLI introduces minimal visual distortion artifacts. This should be less objectionable
than the compression artifacts that appear in other image formats, eg. JPEG,
JPEG 2000, and JPEG XR/HD Photo. Images are provided for readers to evaluate
subjective quality themselves.
At a typical JPEG compression ratio of 15:1, "DLI -or" compresses on average
2.2x JPEG at the same PSNR. However, JPEG performs significantly better visually
than PSNR results indicate. DLI's best visual mode "DLI -ov" averages 80% higher
compression (1.8x) than JPEG, and DLI's default mode averages 65% higher
compression (1.65x) than JPEG. At higher compression ratios, these percentages
increase as DLI degrades more gracefully, often resulting in over twice JPEG's
compression. As another point of reference, the best JPEG 2000 codec I have
tested, Kakadu averages 20% higher compression (1.2x) than JPEG. Therefore,
DLI's compression improvement over JPEG 2000 exceeds the improvement of
JPEG 2000 over JPEG.
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