Re: gEDA-user: Titleblocks: unlocking and filling in.

[Bert Douglas <bertd@xxxxxxxxxxxxx>]

Charles Lepple wrote:
> On Sat, 18 Dec 2004 07:26:59 -0700, Kim Lux <lux@xxxxxxxxxxxxxxxxxxx> wrote:
>
> > I guess it depends on your usage.  We send CAD files created by qcad as
> > jpegs all the time and I've yet to have anyone complain.

JPEG is intended for use on "continuous tone" images.  That is -- 
photographs.  The heart of jpeg is the DCT (discrete cosine transform). 
 There is an assumption of smoothness over an 8x8 DCT cell.  Computer 
generated line drawings violate the basic assumption of smoothness.  And 
computer drawings tend to use just a few discrete colors, rather than 
continuous tones, as in a photograph.

Remember that JPEG stands for "joint photographic expert group", whereas 
PNG stands for "portable network graphics".

Computer generated images generally compress better with LZW techniques, 
as used in PNG.

JPEG is lossy and produces an approximation of the original photograph.
PNG is lossless and preserves all details of the original graphic.