Don't be too quick to dump PNG. PNG is lossless compression. It is not
proprietary or copyrighted - the specs for creating and handling PNG are
freely available, anyone can implement it. Current web browsers support it
automatically, obviating the need to download and install a plugin.
MrSID uses the proprietary 'Discreet Wavelet Transform' for image
compression. Judging from Lizardtech's demo images
(http://www.lizardtech.com/products/mrsid/dwt.html), DWT is not lossless
compression. I would like to see a side-by-side comparison of SID & PNG.
This is not too say PNG is technically better or worse than SID - flatly, I
don't know. Rather, I have an instinctive distrust of any file or image
format which is "owned" by a single company.
cheers,
-matt
the Portable Network Graphic homepage: http://www.cdrom.com/pub/png/
For an overview and comparison of various types of image compression see:
http://www.lanl.gov/projects/ia/stds/ia680120.html
To see some side by side comparisons browse to: http://bi.org/~nas/pics/.
For other 'wavelet transforms'-based compression info see:
http://www.rma.ac.be/~jma/
>Leslie Last wrote:
>> We have a customer who wants to read thousands of 1:500 scale drawings
that
>> have been scanned from base maps with cables drawn onto them. The raster
>> format they use for storage is PNG, since it is so much more compressed
>> than LZW TIF or JPG.
>
>Hi All!
>
>This seems as an obvious case for MrSID.
>Never mind the PNG format and go for SID instead. Then it will be
>possible to scan at full resolution, and yet retain all info in the
>drawings to the smallest detail.
>I do not at this point know if the SID squisher cab handle PNG but the
>Lizard should know.
>The SID handler for MapInfo is due shortly (I hope).
>
>Find out all about MrSID at the Lizard's den
>http://www.lizardtech.com/
>(newly redecorated - sorry that they lost some of the better samples
>when moving)
>
>Regards, Mats.E
>--
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