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#1
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Crazy Comp...
Two files compressed from an original with 16,777,216 pixels and 16,777,216
colours... One is a .png file, 133,450 bites... http://www.blind-apertures.ca/pics/16MillionColours.png The other is a .jpg, 7,416,217 bytes... http://www.blind-apertures.ca/pics/16MillionColours.jpg Which one has lost about 3/4 of the original data? Take Care, Dudley |
#2
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Crazy Comp...
On 14/06/2013 23:19, Dudley Hanks wrote:
Two files compressed from an original with 16,777,216 pixels and 16,777,216 colours... One is a .png file, 133,450 bites... http://www.blind-apertures.ca/pics/16MillionColours.png The other is a .jpg, 7,416,217 bytes... http://www.blind-apertures.ca/pics/16MillionColours.jpg Which one has lost about 3/4 of the original data? Take Care, Dudley The JPEG reports just under 4 million colours. Wonderful what lossless compression can achieve on specially contrived data! Visually indistinguishable, at a quick glance. -- Cheers, David Web: http://www.satsignal.eu |
#3
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Crazy Comp...
Dudley Hanks wrote:
Two files compressed from an original with 16,777,216 pixels and 16,777,216 colours... One is a .png file, 133,450 bites... http://www.blind-apertures.ca/pics/16MillionColours.png The other is a .jpg, 7,416,217 bytes... http://www.blind-apertures.ca/pics/16MillionColours.jpg "socket timed out" -- Pablo http://www.ipernity.com/home/313627 http://paulc.es/ |
#4
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Crazy Comp...
On 14/06/2013 23:19, Dudley Hanks wrote:
Two files compressed from an original with 16,777,216 pixels and 16,777,216 colours... One is a .png file, 133,450 bites... http://www.blind-apertures.ca/pics/16MillionColours.png The other is a .jpg, 7,416,217 bytes... http://www.blind-apertures.ca/pics/16MillionColours.jpg Which one has lost about 3/4 of the original data? Considering that the target image is inappropriate for JPEG encoding it has actually done well to achieve a fairly close visual similarity. Photoshop isn't the best at this by any means. PSPro JPEG manages 5,502,195 bytes and 4007721 colours as a JPEG and 1,754,469 bytes and 16,377,913 colours as a J2k (lossy) Moral of the story you need to think about which method of compression you use on line art and test pieces intended to break JPEG encoders. -- Regards, Martin Brown |
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