[thelist] compression / uncompression

kasimir-k kasimir.k.lists at gmail.com
Fri Jan 18 14:55:39 CST 2008

Bob Meetin scribeva in 18/01/2008 15:19:
> He has said several times that 
> when you send pics through email, particularly ones that need to be 
> compressed to be attached, that there are bytes lost or that they lose 
> quality in the process.

My little inner semiotician picked something here :-) Assuming that he 
said exactly what you here said he said, then he is saying
a) emailing pics in general reduces their quality
b) some pics must be compressed, or they can't be attached
c) the effect a) is more pronounced in pics b)

The first one is not true: the bytes that are attached will be the bytes 
that are received (if they are not, then there is a problem :-)

So c) has more truth: if uncompressed pics do not lose quality (bytes), 
then compressed pics lose more (note though that there is also lossless 

But what about b? RFC2821 [0] specifies the SMTP, and in section 
says: "...message size restrictions should be avoided if at all 
possible." However, in practice most email services impose some limits, 
e.g. Gmail allows up to 20MB message size [1]. Here the semiotician 
steps in: your client says "to be attached" - so he is not referring to 
restrictions set by SMTP servers, but his email client. It could be also 
his OS: in Win XP, when I right click on an large image, select "send 
to..." -> "email recipient", then Windows offers me an option to reduce 
the size of the image - Windows seems not to be too good at this though, 
and the resulting quality of the size reduction tends to be sub optimal...

So I'd say it boils down to the size what he sends. If the pics you 
receive from him are say max 1MB, then you might recommend him an 
alternative way to send them (e.g. Gmail). You see, even though he is 
incredibly intelligent engineer, it could be that he is not a computer 
engineer, but an old school civil engineer who is fairly clueless with 
all this new things like email...


[0] http://www.ietf.org/rfc/rfc2821.txt
[1] http://mail.google.com/support/bin/answer.py?answer=8770

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