PMBC IFF High-color Image Format

Reserved for Black Belt Systems 91.12.01

TITLE: PMBC - It's Coming... thoughts?
We have created an entirely new way to store high-color
images, specifically 24 bit accurate images. The storage
format includes the ability to save 8 bit alpha information
(or just a simple 1 bit mask, as appropriate) with
the image.

This method is called PMBC.

PMBC provides compression that ranges from a possible
maximum of thirty to forty times that of IFF 24, including
the alpha channel when the IFF24 does not, to an average
gain of about 16% over IFF24.

PMBC is totally lossless; in that way, it is similar
to IFF24 - that is why I compare it to IFF24, rather
than JPEG, for instance. JPEG provides a much larger
compression, but at the cost of accuracy which is totally
unacceptable in scientific and medical work. As you
may know, one of the board members of Black Belt is
a Neuro-Radiologist... and he doesn't want to hear
about "lossy" compression. :^)

PMBC is available now, commercially, as a Public Interface
load/save module for our Imagemaster and Image Professional
products. We've gotten a fair bit of feedback on this
initial release of it, and it's generally been positive.
Only one user has managed to "break" the compressor
in the sense that the PMBC file is larger than the
equivalent IFF 24 file. We've not yet seen this mythical
file, but we're REAL interested. :^)

Another benefit of PMBC is that the compressed files
are highly ordered when you are talking about the PMBC
file that is created... as a result, when you LHARC
a PMBC file, you get another significant gain. In almost
all cases, a PMBC file is smaller than the same image
file in IFF24 _after_ it's been compressed with LHARC.
Then you can LHARC the PMBC file and pick up even more.
This makes it very attractive for lots of uses.

PMBC is "aware" of various colorspaces; C, M, Y, K
results, greyscale results, and R, G and B results
all compress exceedingly well, eliminating the need
for a separate (like the 8 bit IFF) format for files
in these limited spaces. In fact, in a PMBC file, if
you have a _region_ that is inone of these spaces,
that region will achieve significant;y higher compression
than the rest of the image, resulting in an overall
very high gain in, er, shrunkenness. :^)

All of this is transparent to the user, all they see
is save and load.

The compressor itself is currently written in C, and
isn't by any means optomized for speed; yet it appraches
the speed of a similarly coded IFF24 compressor. We
have high hopes for excellent compression speeds.

Now, here is where we are at. Currently, there is no
decent way to losslessly compress an image other than
IFF24. PMBC can save the user in the region of 16megs
per 100mb partition, which isn't an unreasonable amount
of images for many users - and 16 megs is a lot to
get back "for free" (no loss of data). We're interested
to hear what developers in general think of the compression
and the features I've described here. Those who wish
to experiment with it can do so now, within Imagemaster
or Image Professional.

This is not _currently_ in an IFF wrapper, and PMBC
itself is subject to improvement by us w/o notice until
we are at the point where we are ready to "w5rap it
up", he said punningly.

Until then, the technology will remain proprietary.

Thanks for your time.

Ben Williams