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authorwiz <wiz@pkgsrc.org>2010-01-17 11:53:40 +0000
committerwiz <wiz@pkgsrc.org>2010-01-17 11:53:40 +0000
commit9f4ac2d4da893c4c5254efbbbd76dde1260020c8 (patch)
treea630f468cf4a53d1c38d56884701f62362bd996c /emulators/kenigma
parent46a871e44aca4e44aecefe2917e60f8e0861eeaf (diff)
downloadpkgsrc-9f4ac2d4da893c4c5254efbbbd76dde1260020c8.tar.gz
Update to 8:
The current version is release 8 of 10-Jan-2010. Version 8 of the JPEG software introduces basic new features for image coding application and comes with an essential update of the original JPEG specification. New features and enhancements have been developed for the three major parts of the IJG library: the compression, the decompression, and the transcoding parts. These parts are represented by the three major tools of the IJG software: cjpeg (compress JPEG), djpeg (decompress JPEG), and jpegtran (transcode JPEG - lossless): IJG Tools New jpegtran -scale lossless resize feature A new option has been added to the jpegtran tool and transcoding library: -scale M/N Scale output image by fraction M/N, eg, 1/8 Currently supported scale factors are M/N with all M from 1 to 16, where N is the source DCT size, which is 8 for baseline JPEG. If the /N part is omitted, then M specifies the DCT scaled size to be applied on the given input. For baseline JPEG this is equivalent to M/8 scaling, since the source DCT size for baseline JPEG is 8. CAUTION: An implementation of the JPEG SmartScale extension is required for this feature. SmartScale enabled JPEG is not yet widely implemented, so many decoders will be unable to view a SmartScale extended JPEG file at all. New djpeg -scale feature The -scale option of the djpeg tool and decompression library has been extended: -scale M/N Scale output image by fraction M/N, eg, 1/8 Currently supported scale factors are M/N with all M from 1 to 16, where N is the source DCT size, which is 8 for baseline JPEG. If the /N part is omitted, then M specifies the DCT scaled size to be applied on the given input. For baseline JPEG this is equivalent to M/8 scaling, since the source DCT size for baseline JPEG is 8. New cjpeg features Two new features have been added to the cjpeg tool and compression library: -quality N[,...] Compression quality (0..100; 5-95 is useful range) -scale M/N Scale image by fraction M/N, eg, 1/2 The -quality option has been extended for support of separate quality settings for luminance and chrominance (or in general, for every provided quantization table slot). This feature is useful for high-quality applications which cannot accept the damage of color data by coarse subsampling settings. You can now easily reduce the color data amount more smoothly with finer control without separate subsampling. The resulting file is fully compliant with standard JPEG decoders. A new -scale option is provided with cjpeg which complements the corresponding djpeg -scale option. The supported range of scaling factors is 8/N with all N=1...16. This means you can now easily alter the nominal spatial resolution of a given source image while compressing to JPEG without additional resampling. For example, if you have an image sensor providing an effective capture resolution of 2268x1512 pixels (HI resolution), you can now directly generate a MED resolution of 1512x1008 pixels (-scale 2/3) and a LOW resolution of 1134x756 pixels (-scale 1/2) from the sensor source resolution with the library while compressing to JPEG without additional resampling. (An efficient 12x12 FDCT is used in the -scale 2/3 case, and an efficient 16x16 FDCT is used in the -scale 1/2 case instead of the standard 8x8 FDCT inside the library, ensuring high-quality downscaled results - the resulting file is fully compliant with standard JPEG decoders.)
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