Naked Science Forum
Non Life Sciences => Technology => Topic started by: McQueen on 01/10/2007 14:06:39
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I admit that I have always been fascinated by the concept of image compression. Imagine taking a picture, take a picture of a landscape with plenty of tress for example, with all of its myriads of details and then compressing all of that information to a fraction of its original size and then, through the magic of software, reproducing every detail of that original image. Although I am not a professional software engineer, image compression had been my pet fad for a certain period of time, I studied and wrote IC programs on (RLE) run length encoding, and DCT ( The Discrete Cosine Transform) popularly known as the JPEG and MPEG standard and even wrote my own fixed length encoding program that always returned the same percentage of compression regardless of the content of the image and in addition was extremely efficient, being an almost zero loss compression program. Today most of these techniques are almost obsolete due to the enormous leaps made in hardware processing capabilities, although JPEG and MPEG have, rightly I think, been established as an industry standard. But I was just wondering has anything new come along? The coming thing at the time was fractal image processing which promised enormous things, take just two or bits of information from an image for example and reproduce faultlessly the whole image! Has anything come of it, anything new?
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About six or seven years ago someone told me about a technology which seemed to be much better than jpeg. He showed me how jpeg images were compromised because of their tendencies to cause squares and rectangles to appear in the image at higher compression. The technology he showed me not only achieved better compression than the compressed images were better quality, too.
I've just done a quick google - I think the technique was this one (http://www.freepatentsonline.com/6934420.html)
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sounds good! but a little outdated, I think, it's just like the IC piston engine and trnsportation, you have to look at something new, just mixing up known technolgy may not be the answer. Huffman has been around since 1970 and run length encoding for almost as long, so I don't think that this is anything revolutionary, also it probably won't do better than JPEG or MPEG. P>S. If you have a diagnoal line in a JPEG image you are ging to have problems!
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I remember seeing a TV program a few years back about a British company that was making a fortune using fractal techniques for transmitting video footage.
I know what fractals are, but how the hell it can be used for video streaming is beyond me. There was a slo-mo demo of the technique where the software took a portion of the image and checked the rest of the image for a match. I remember thinking at the time that doing that would surely take longer than just transmitting the video raw. How can they get it fast enough to work?
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As an interested observer, it seems that fractals never really made it to the big-time - I think the major issue was that compression is extremely computationally demanding.
JPEG2000 is a newer enhancement of the JPEG standard which promises to solve some of the JPEG problems (degrades more gracefully at higher compressions, without "blockiness" artifacts), but on the web at least, its benefits don't seem to outweigh the fact that JPEG2000 is a much less universal currency. I believe JPEG2000 is based on wavelet coding, and degrades to a more natural "blurriness" if over-compressed.
It's worth remembering that the JPEG standards specify exactly how a compressed image-file is to be reconstructed, but the psychovisual model used to decide what image-data to keep and what to discard during the compression process is open. In my experience, modern JPEG compression algorithms and visual models seem to a achieve "near-visually lossless" compression with about half the filesize of algorithms from 10-15 years ago. My gut feeling is that we've probably got as far as we can with DCT-based compression systems. JPEG is so universal and entrenched that some new standard would have to be markedly better to actually catch on in the mainstream.
I suspect most new research is on compression of video, where further advances in motion-analysis and compensation will gain much more compression-advantage than minor tweaks to static-image algorithms.
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One of the issues is to decide what it is that you are trying to compress. If you are trying to compress art graphics (i.e. things with sharp edges, such as text, or line drawings), then JPEG is far from ideal - JPEG was designed for photographic images with relatively smooth blends from one are to the next.
PNG (being the successor to GIF - with both advantages and disadvantages over GIF) is my preferred format for anything that is not photographic in nature.
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One of the issues is to decide what it is that you are trying to compress. If you are trying to compress art graphics (i.e. things with sharp edges, such as text, or line drawings), then JPEG is far from ideal - JPEG was designed for photographic images with relatively smooth blends from one are to the next.
PNG (being the successor to GIF - with both advantages and disadvantages over GIF) is my preferred format for anything that is not photographic in nature.
It's a pity Microsoft don't share your enthusiasm.
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http://cgi.ebay.co.uk/Microfleur-Microwave-flower-press_W0QQitemZ230177386873QQihZ013QQcategoryZ57200QQssPageNameZWDVWQQrdZ1QQcmdZViewItem
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One of the issues is to decide what it is that you are trying to compress. If you are trying to compress art graphics (i.e. things with sharp edges, such as text, or line drawings), then JPEG is far from ideal - JPEG was designed for photographic images with relatively smooth blends from one are to the next.
PNG (being the successor to GIF - with both advantages and disadvantages over GIF) is my preferred format for anything that is not photographic in nature.
It's a pity Microsoft don't share your enthusiasm.
I am not quite sure what you mean.
I realise that Microsoft were slow on the uptake (after all, the really do not like open standards), but IE7 certainly does support PNG - any other Microsoft product, I don't know, since I am probably not using it (even IE I only use in certain circumstances).
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i have implement jpeg2000 codec in fpga,if anyone feel interesting of it,you can contact me.