I am writing a jpeg decoder based on standard itu-t81. I can find links to itu-t81.pdf everywhere, but now I would also like to obtain the part 2 mentioned in this one, so I can test my decoder for compliance. I have googled around but can't find it.
> I am writing a jpeg decoder based on standard itu-t81. I can find links > to itu-t81.pdf everywhere, but now I would also like to obtain the part > 2 mentioned in this one, so I can test my decoder for compliance. I > have googled around but can't find it.
> Does anybody know where to find it?
Sure. It's an ITU and ISO standard, so you can buy them from the ITU or the ISO. URLs for the ITU and the ISO are obvious. (-: "Free copies" you find in the net are likely illegal, or cover only the FDIS state of the standard, i.e. may contain errors that have been addressed in later corrigenda.
Furthermore, I would also suggest to check the following book:
William B. Pennebaker, Joan L. Mitchell: JPEG Still Image Data Compression Standard Van Nostrand Reinhold, New York, ISBN 0-442-01272-1
> Sure. It's an ITU and ISO standard, so you can buy them from the ITU or > the ISO. URLs for the ITU and the ISO are obvious. (-: "Free copies" you > find in the net are likely illegal, or cover only the FDIS state of the > standard, i.e. may contain errors that have been addressed in later > corrigenda.
Well I obtained part 1 from the W3C organisation website, so unlikely to be illegal :)
Thanks for the info. I guess I'll have to buy the part 2 then.
> Furthermore, I would also suggest to check the following book:
> William B. Pennebaker, Joan L. Mitchell: > JPEG Still Image Data Compression Standard > Van Nostrand Reinhold, New York, ISBN 0-442-01272-1
> Aka, "The Pink Book". (Yes, it's really pink.)
Thanks for the tip, but I already know a lot about the compression principles used in Jpeg, and it's a bit pricy at US$155. Btw I'm not very interested in the arithmetic coding and hierarchical compression parts of Jpeg, I just want a decompressor that handles about 99% of all jpegs available (huffmann sequential and progressive, IDCT). I guess things like using MMX and SSE2 for the IDCT stage are not in the book anyway :)
> Nils wrote: >> Does anybody know where to find [T.81 part 2]?
> Sure. It's an ITU and ISO standard, so you can buy them from the ITU or > the ISO. URLs for the ITU and the ISO are obvious. (-: "Free copies" you > find in the net are likely illegal, or cover only the FDIS state of the > standard, i.e. may contain errors that have been addressed in later > corrigenda.
I think you're looking for ITU T.83, a.k.a. ISO10918-2.
You used to be able to sign up with ITU once a year to download up to three standards a year for free. I don't know if that still works.
Pete Fraser wrote: >>>Does anybody know where to find [T.81 part 2]?
>>Sure. It's an ITU and ISO standard, so you can buy them from the ITU or >>the ISO. URLs for the ITU and the ISO are obvious. (-: "Free copies" you >>find in the net are likely illegal, or cover only the FDIS state of the >>standard, i.e. may contain errors that have been addressed in later >>corrigenda.
> I think you're looking for ITU T.83, a.k.a. ISO10918-2.
> You used to be able to sign up with ITU once a year to download up to three > standards a year for free. I don't know if that still works.
The second alternative is to become a member of a standardization group. If you're working for a university, the membership is, at least for Germany and the DIN, for free.
> Thanks for the tip, but I already know a lot about the compression > principles used in Jpeg, and it's a bit pricy at US$155. Btw I'm not > very interested in the arithmetic coding and hierarchical compression > parts of Jpeg, I just want a decompressor that handles about 99% of all > jpegs available (huffmann sequential and progressive, IDCT). I guess > things like using MMX and SSE2 for the IDCT stage are not in the book > anyway :)
I suggest you take a visit to your nearest University library. They will generally have some ISO and ITU documents on hand, and probably have a subscription that will allow them to access to the online archives. A reference librarian can probably hook you up with the appropriate file in minutes. (Different libraries will have different methods for protecting the copyrighted content - you may be restricited to viewing the document on a locked-down PC.)
It is a shame that the standards bodies charge so much for these documents, as it locks out ordinary citizens from a lot of access. But until you come up with an alternative method of funding their activies, I'm afraid we are stuck with the status quo.
> Well I obtained part 1 from the W3C organisation website, so unlikely > to be illegal :)
The JPEG standard text (10918-1/T.81) is really in the public domain now, it is available from various places for free.
> Thanks for the info. I guess I'll have to buy the part 2 then.
This part 2 ("compliance testing") is not really necessary. You are probably wasting your time to dig this thing up.
Anyway, there is an opportunity on the ITU site to sign up a registration for downloading up to three documents per year for free. It is a bit difficult to find, but then I did this and it worked.
> > Furthermore, I would also suggest to check the following book:
> > William B. Pennebaker, Joan L. Mitchell: > > JPEG Still Image Data Compression Standard > > Van Nostrand Reinhold, New York, ISBN 0-442-01272-1
> > Aka, "The Pink Book". (Yes, it's really pink.)
> Thanks for the tip, but I already know a lot about the compression > principles used in Jpeg, and it's a bit pricy at US$155.
This book is still the best reference for JPEG in existence today (well, until I write my own book...:) and highly recommended for anyone doing serious JPEG work.
> Btw I'm not very interested in the arithmetic coding and hierarchical > compression parts of Jpeg, I just want a decompressor that handles > about 99% of all jpegs available (huffmann sequential and progressive, > IDCT). I guess things like using MMX and SSE2 for the IDCT stage are > not in the book anyway :)
The DCT/IDCT part is in fact the weakest point in this book, unfortunately. There are no useful algorithms given for practical implementation, and it lacks explanation of the fundamental DCT property for image representation. That is the reason that all subsequent image coding research went wrong. And that is the reason that I have to write my own book. Joan Mitchell has already declared to be editor of my book (and contributing some content...:). By the way, the "Pink Book" is no longer available in the "Van Nostrand Reinhold" edition - it is now available in a "Springer Publishing" edition, as Joan Mitchell told me at the Geneva meeting this year (the new book will also be published there).
Regards Guido Vollbeding Organizer Independent JPEG Group
Nils wrote: >>Furthermore, I would also suggest to check the following book:
>>William B. Pennebaker, Joan L. Mitchell: >>JPEG Still Image Data Compression Standard >>Van Nostrand Reinhold, New York, ISBN 0-442-01272-1
>>Aka, "The Pink Book". (Yes, it's really pink.)
> Thanks for the tip, but I already know a lot about the compression > principles used in Jpeg, and it's a bit pricy at US$155.
Who said about buying? (-: The nearest university to your place will likely have it. Check in the computer science, electrical engineering or communications engineering department.
> Btw I'm not > very interested in the arithmetic coding and hierarchical compression > parts of Jpeg, I just want a decompressor that handles about 99% of all > jpegs available (huffmann sequential and progressive, IDCT). I guess > things like using MMX and SSE2 for the IDCT stage are not in the book > anyway :)
Part-2 might be very handy, but in reality you'll find a couple of JPEGs around that do not really follow the standard anyhow, so that part might be not as useful as you might think immediately. First of all, 99% of the JPEGs out there only use a small percentage of the features, but it's not too unlikely that you'll find some that do not follow the standard but you would like to get decoded. For that, collect experience by experimenting, or (probably a faster approach) get in touch with people that do have this experience.
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