Subject:
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Re: Parts Cataloging Program
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Newsgroups:
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lugnet.cad.dev
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Date:
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Tue, 28 Mar 2000 16:16:09 GMT
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Viewed:
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1770 times
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In lugnet.cad.dev, Rui Martins wrote:
> > What are the preferred file formats for these pics? Right now I have
> > ldglite dumping png files since they're true color, fairly well compressed,
> > and not lossy like jpg. I could make bmp an option since I had that
> > working before I switched to png. I could add others if people really
> > want them.
>
> JPG is NOT lossy, i.e. it's NOT required to be lossy, it can be defined
> to be 100% accurate !
Is there some other way to compress JPG files, besides lowering the
quality? Whenever I save a JPG file with 100% accuracy, the saved file
is huge (ie, about the same size as a similar BMP file).
> > In lugnet.cad.dev, Don Heyse wrote:
> >
> > Png is a good format, but still not very widespread. LDAO reads bmp 10x
> > faster than anything else, and doesn't recognize png.
> >
> > I usually do gif for web stuff, and bmp-rle for local stuff.
> >
> > Steve
>
> Actually I think that the best format is the GIF format, due to the type
> of compressing it uses and our specific renderer used for the cataloging
> task.
>
> - BMP in it's pure form, it's just like a memory dump, but with RLE
> compression could be good, but I don't actually know how the compression
> algo to provide an opinion. Also I think that BMP-RLE PROGRAMS have to PAY
> ROYALTIES or a LICENCE to be able to be distributed, but I' NOT sure
I've never heard of any kind of restriction on distribution of RLE
files. I've gotten my BMP/RLE information from Microsoft docs. Since
they wrote the BMP format, they'd hold any copyrights or patents.
RLE compression is not as good as GIF's LZW compression. What RLE does
is to replace single-color pixel sequences with a simple color/count
code. It can only compress within a single row of pixels, and can't
compress vertically. RLE is limited to 16 or 256 colors.
> - GIF is good for draw type images, lots of equal pixels, with pixel
> sequences also compressed. This format could also have to have a LICENCE,
> since it's registered by someone (don't remember who), but due to the
> internet, everybody uses it, and no one is beeing persued ! ;)
UniSys is the company which holds a patent on the LZW compression
algorithm employed in the GIF format. Any software which codes or
decodes GIF-format files needs to obtain a license from UniSys. It
seems reasonable that a program which processes GIF files, but does not
touch the LZW-encoded data blocks[1] would not need a license. Using
GIF files, or using a software package which manipulates GIF files, does
not require a license.
But, as Rui noted, UniSys is not going after everyone for violating the
patent.
Steve
1) LDAO does this -- the HTML Generator uses ImageMagick to convert BMP
to GIF, and then LDAO tweaks the palette entries in the GIF files,
without touching the data blocks.
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Message has 1 Reply:
 | | Re: Parts Cataloging Program
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| (...) This problem is why I chose PNG. It compresses flat shaded images quite well and still retains the true color pixels. My comprehensive testing of one sample image (the one on the LdGLite web page) put the PNG file at about half the size of the (...) (24 years ago, 28-Mar-00, to lugnet.cad.dev)
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Message is in Reply To:
| | Re: Parts Cataloging Program
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| (...) JPG is NOT lossy, i.e. it's NOT required to be lossy, it can be defined to be 100% accurate ! (...) Actually I think that the best format is the GIF format, due to the type of compressing it uses and our specific renderer used for the (...) (24 years ago, 27-Mar-00, to lugnet.cad.dev)
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