PNG graphics format?

[Mark Adler]

>> If we could offer a "1" that used JPEG-ish
>> compression, I'd be perfectly willing to switch everything over to PNG

In the PNG group we decided that a) we wanted png to be associated  
exclusively with lossless, so that if you were using png, you knew you were  
using lossless.  b) the existing format for jpeg (jfif) was not "broken" in  
any sense.  (If it ain't broke, don't fix it.)  It works fine, is portable,  
understood by lots of software.  In constrast to gif, which was broken even  
before the lzw wake-up call.

There is one area though where jpeg/jfif is lacking, and that's the lack of  
a transparency/alpha channel for use on, for example, web pages.  A solution  
suggested was to have for a jpeg file an associated png file with just a  
transparency or alpha channel when you want that function.  This also extends  
to other image types (if any).

>> Check out the PNG and JPEG versions of the PNG logo at

Yep, you should use jpeg when it makes sense and use png when it makes  
sense.  They are complimentary.  jpeg works fine as is, and so does not need  
to be incorporated in png.  The compression type byte in png is for future,  
more effective *lossless* non-patented compression methods.  For example I'd  
like to see the next method be something more effective for bilevel images  
(but it can't be jbig).

mark