Image-compression software


JPEG may be the tried-and-true photo-format for the Web, but it can still add blocky artifacts to images. Several companies have released Adobe Photoshop plug-ins that compress images without introducing those unsightly distortions. Ones to add to that list are LuraTech’s LuraWave and BitJazz’s PhotoJazz 2. PhotoJazz, intended largely for use with pre-press applications, is based on a lossless compression scheme. But, it offers relatively limited compression ratios – an average of 2.5:1, compared with 10:1 or more for lossy compression schemes, such as JPEG. However, PhotoJazz gives you smaller files than Photoshop’s TIFF LZW option. The $29 entry-level version produces RGB output only, the $79 version provides CMYK output as well, and the $99 version supports output of 16-bit multi-channel files. All three include PhotoJazz XT for importing PhotoJazz images into QuarkXPress, and PhotoJazz QT, which opens and saves PhotoJazz images using QuickTime programs. BitJazz offers a free version that opens PhotoJazz images in Photoshop and most QuickTime programs. LuraWave competes not so much with PhotoJazz as with MrSID. Both are based on wavelet technology, a lossy compression scheme that yields fewer distortions at any given compression ratio than JPEG. LuraWave’s compression scheme appears to be just as effective as MrSID’s. Images compressed at 10:1 had no perceptible artifacts; images compressed at 20:1 had only minor artifacts. LuraWave also includes a lossless option, but its compression ratios appear to be no better than LZW’s. LuraWave’s best feature is its price: just $79, compared with MrSID’s £299. Unfortunately, LuraTech does not offer a free Photoshop plug-in for opening the files.
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