Test Methodology (DLI Image Compression)

DLI is compared with JPEG, JPEG 2000, and Microsoft's HD Photo (basis for JPEG XR).

Software and options used

DLI v1.0

DLI c -or -q # input.ppm image.dli

DLI d image.dli output.ppm

JasPer v1.900.1 JPEG2000 software found at http://www.ece.uvic.ca/~mdadams/jasper/

jasper --input input.ppm --output image.jp2 -O rate=#

jasper --input image.jp2 --output output.ppm

Kakadu v6.1 JPEG2000 software found at www.kakadusoftware.com

kdu_compress -i input.ppm -o image.jp2 -rate #

kdu_expand -i image.jp2 -o output.ppm

IJG JPEG v6b found at www.ijg.org

cjpeg -o -q # input.ppm > image.jpg

djpeg image.jpg > output.ppm

wmpencapp -i input.ppm -o image.wdp -q #

wmpdecapp -i image.wdp -o output.ppm

Notes:

By default, DLI and IJG JPEG employ chrominance downsampling while JasPer, Kakadu, and HD Photo do not.

By default, Kakadu uses visual weighting factors for better subjective quality, but lower objective results.

Images used

Lena (512x512 color) and Peppers (512x512 color) images found at the USC-SIPI image database.

kodim19 (512x768 color) and kodim23 (768x512 color) images found at http://r0k.us/graphics/kodak/

My web links to the Barbara (787x576 color) image are broken, and I haven't found a current one.

If you have one, I'd appreciate an updated link.

Performance evaluation

Objective measures PSNR and SSIM are presented in graph form. The PSNR data is also presented in relative

PSNR form for easier observation of the difference between codecs, with DLI as the reference. A fourth graph

shows output filesizes of each codec as a multiple of DLI's for equal PSNR values. Following the graphs are

images provided for visual comparison. For a fixed compression ratio, each codec produces an image which is

displayed along with a visualization of the PSNR data. Each codec also produces an image at a fixed PSNR value.

These images are used to illustrate that each codec may have different subjective quality. Magnified sections

of these images are provided for easier observation of their quality.

Note: All images are losslessly converted to PNG format for display on this website.

Acknowledgment

Thank you to the MSU Video Group for their MSU VQMT v1.52 software.

The software was used for this objective comparison.

MSU Graphics&Media Lab, Video Group, MSU filters and codecs