Breakthrough In JPEG Compression

Kris_J writes "The makers of the (classic) compression package Stuffit have written a program that can compress JPGs by roughly 30%. This isn't the raw image to JPG compression, this is lossless compression applied to the JPG file. Typical compression rates for JPGs are 2% to -1%. If you read the whitepaper (PDF), they are even proposing a new image format; StuffIt Image Format (SIF). Now I just need someone to write a SIF compressor for my old Kodak DC260."

Comments

Fractal image format

[nmg196]

I would have thought that rather than 'zipping' an existing image format to create a new one just to save 30%, they'd be better off improving the original image compression algorithm or coming up with a new one.

Quite a while ago (years!) I had a program which could compress images into a fractal image format. It was amazing - the files were much smaller than JPEGs but looked a lot better. The only drawback was that it took ages to compress the images. But with the extra CPU horsepower we have today I'm surprised fractal image compression hasn't become more prevailant. It would still probably be useless for digital cameras though as it would probably be impossible to implement the compression in hardware/firmware such that it could compress a 6+ megapixel image within the requisit 1-2 seconds.

Does anyone know what happened to fractal image format files (.fif) and why they never took off?

Re:Fractal image format

[imsabbel]

Believe him, i used the same programm. It was from iterated systems (they are long gone).
Its not on their homepage anymore. I dont know if they really used IFS or they just did some wavelets and faked it, but the compression was honestly much better than jpeg. (but of course slower, too. IIRC, compressing a 1024x786 picture took about 40-50 seconds on my pentium.
What was unique was the viewer. it was "resolutionless", so you could zoom in farther than the original without pixelation. Shapes started to look painterly then, as if traced by outlines, which would actually be in favour of it really being a fractal compressor.
No idea why it was canned.

Re:Fractal image format

[Anonymous Coward]

Does anyone know what happened to fractal image format files (.fif) and why they never took off?

Hard to implement. Patent mess. CPU requirements. No better fidelity [they have just as many artifacts as JPEG, but the artifacts are 'nicer looking']. Massive increases in available bandwidth. Fractal wierdness with editing, you always have to convert back to raster anyway.

The tech has found niche applications though, such as image scaling : Lizardtech's Genuine Fractals is pitched as an image rescaling tool, but it's basically the same tech as you're talking about. In this case, it's just a save/load plugin for photoshop. You save any file as a fractal and then when you reopen it it asks you how big you want it. 200%? 500%? Whatever, it scales it up and looks much the same, but with a strange kind of fractal painting-like effect.

The strange thing is that if you zoom in on one of these scaled images you start to see shapes that weren't in the original -- that weren't in the original scene, though at normal zoom the image might look perfectly normal. It's kind of creepy.

Re:Fractal image format

[Corpus_Callosum]

I concluded that it isnt practical for general use, it took too much time to compress an image (alright it was five years ago and so today it probably wouldnt matter), but most importantly there is no easy general compression solution for all images (for instance one that compresses tree pics well wont do faces well and vice versa).

I did some basic expirementation with Genetic Algorithms and fractal compression and I can tell you, GA does solve the problem. Not only solve it, but obliterates it. With GA, fractal compression can achieve compression ratios and quality that are unheard of with other techniques.

Of course, this is to be expected, after all - it is what nature does with us. Our genecode is the compressed image, our bodies are the uncompressed results.

Interesting thought food, huh...

What's the point?

[CliffSpradlin]

The linked page shows average decompression times of 6-8 seconds for 600-800 KB files, rising with the size of the file. Who would benefit from this? It's obviously too slow to speed up web pages, and would be far too CPU intensive for consumer cameras. Professional photographers would have no use for this since they would use RAW images.

I mean, it's cool and all to be able to compress JPGs by that much more, but the size gains are negated by the time it takes to decompress them. This seems just like those super high compression algorithms that have rather amazing compression rates, but take -forever- to compress or decompress, making them unusable. The difference is those are obviously and labeled as simply for scientific research into compression, but Aladdin seems to be trying to market this product for public consumption. The listed uses ( http://www.stuffit.com/imagecompression/ ) seem trivial at best.

Who's gonna be buying this?

-Cliff Spradlin

Questions

[RAMMS EIN]

The linked page did not answer some of my questions:

1. Does this only work for JPEG, or also for other (compressed or plain) files?

2a. If it only works for JPEG, why?

2b. If it works for others, how well?

Anybody who can answer these?

Re:Questions

[ottffssent]

The whitepaper suggests they're tearing out the run-length encoding that's the final step in jpeg and replacing it with something more space-efficient.

In a nutshell, JPEG works like:

Original image data -> frequency domain -> high frequencies truncated (via division matrix) -> RLE

RLE is fast, but not terribly compact. Replacing it with something better improves compression. However, RLE generates not-very-compressable output, which is why traditional compression software does poorly. I imagine if you took a jpeg, undid the RLE, and zip compressed the result, you'd get something close to what the stuffit folk are claiming. If someone wants to try that, I'd be interested in the results.

Wow, that IS a breakthrough!

[wcitechnologies]

I have a friend who's father is a professional photographer. He has gigabytes and gigabytes of images stored for his customers, should they want to order re-prints. They're thinking about setting up raid terabyte file server. I can certainyl say that this is good news for them!

Re:Only lossyless

[lougarou]

JPEG is (roughly) a discrete cosine transform, followed by a filter on high frequencies, followed by Huffmann encoding (which is lossless). This is probably the Huffmann encoding that they did remove and replace with one of the more efficient compression algorithms, and something that could indeed be much more efficient than simple huffmann encoding. So they still take advantage of all the strengths of JPEG related to the human perception model, but they still gain in compression. Huffmann is great to compress oft-appearing sequences, and is a great general-purpose lossless encoding, but there are other that do a better job of it.

In other words, you did not understand what they did.

Possibly just a rehuff?

[tangent3]

The quantised DCT coefficients of a JPEG image are compressed using a JPEG standard huffman table. From what I've seen, this table is far from optimized even for "the average of the majority" of images out there.

Ogg Vorbis stores its own huffman table in its own stream. The default encoder uses a table optimized for the general audio you can find out there. There is a utility called "rehuff" (goggle it yourself please) that will calculate and build a huffman table optimized for a particular stream and it seems that on average it reduces an Ogg Vorbis filesize by about 5-10%.

Building an optimized huffman table for individual JPEGs will probably yield such improved compression rates too. If the original JPEG tables are less optimized than the Ogg Vorbis ones, the reduction will be even higher. But 30% seems a little... optimistic.

Patents.

[xtal]

I worked in this field for awhile, and the liscencing and other issues sent the company I was with running in the other direction. JPEG was good enough, everyone was using it, so JPEG it was.

Fractal compression is cool.. but encumbered by IP issues. Too bad.