CharLS, a JPEG-LS library

Several groups have compared JPEG-LS / JPEG-2000 compression performance for lossless compression. In most cases JPEG-LS and JPEG 2000 are the best performing standard compression techniques, usually very similar in compression performance.

See for yourself at:
http://www.researchandtechnology.net/pcif/benchmarks.php
http://www.jpeg.org/public/wg1n1816.pdf
ftp://medical.nema.org/MEDICAL/Dicom/DataSets/WG04/compsamples_README.txt
http://www.dpconline.org/docs/reports/dpctw08-01.pdf
http://itohws03.ee.noda.sut.ac.jp/~matsuda/mrp/
http://cimss.ssec.wisc.edu/muri/documents/presentations/workshop4/muri_17_bhuang.ppt

The current speed of charles (encode, decode in milliseconds)

Grayscale:
Size:1024x1024 (16bit) Encode: 44.04 Decode: 36.45 Bps: 4.58
Size:1024x1024 Encode: 32.61 Decode: 26.12 Bps: 1.91
Size:512x512 Encode: 12.20 Decode: 9.69 Bps: 4.24

Color:
Size:1280x1024 Encode: 63.89 Decode: 51.90 Bps: 1.03 (desktop screenshot)

ImageCompression.info sample images
artificial.ppm Size:3072x2048 Encode: 253.59 Decode: 227.73 Bps: 0.65
bridge.ppm Size:2749x4049 Encode:1694.40 Decode:1379.56 Bps: 4.64
flower_foveon.ppm Size:2268x1512 Encode: 400.98 Decode: 333.80 Bps: 1.89