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Fig. 3 —Joint Photographic Experts Group (JPEG) 2000 compression
artifacts in contrast-enhanced transverse chest CT image in 53-year-old woman
with usual interstitial pneumonia. According to pooled readers' responses, 5:1
(second row, column 1) and 8:1 (second row, column 2)
compressed images were indistinguishable from original images (top
row), whereas 10:1 (second row, column 3) and 15:1 (second
row, column 4) compressed images were distinguishable from original
images. Compression artifacts are best seen if original and compressed images
(Figs. S1A–S1E) are downloaded and displayed alternately on same
monitor; these images can be seen in the AJR electronic supplement to
this article, available at
www.ajronline.org.
Subtraction images (third row) and high–dynamic range visual
difference predictor (HDR-VDP) maps (bottom row) represent
mathematical and predicted perceptual differences, respectively, between
original and compressed images at each compression level. Region of interest
for original and compressed images is smaller than that of subtraction images
and HDR-VDP maps. For original and compressed images, window width and level
settings are 1,500 and –600 H, respectively.
