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DLI is an optimizing lossy image compression system. It compresses more than
any commercial or research codec, holding the records for PSNR and MS-SSIM.
The original goal was to achieve maximum compression (rate-MSE distortion)
regardless of computation time. DLI's design has expanded to include an optimize
for visual quality mode, and a "high speed" visual mode 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 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 75% higher
compression (1.75x) than JPEG, and DLI's default mode averages 60% higher
compression (1.6x) than JPEG. As another point of reference, the best JPEG 2000
codec I have tested, Kakadu averages 20% higher compression (1.2x) than JPEG.
DLI's compression improvement over JPEG 2000 exceeds the improvement of
JPEG 2000 over JPEG.
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