[thelist] compression / uncompression

Jason Handby jason.handby at corestar.co.uk
Fri Jan 18 09:30:56 CST 2008

> I have a client who is an engineer, incredibly intelligent.  
> I have had 
> to send large documents, videos, digital images, back/forth.  
> Frequently 
> the pics he sends me are poor quality.  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.
> Rather than argue (he is an engineer...) I just say that if 
> it happens 
> it's negligible.  So be it...  So the question is, Is there 
> any validity 
> to what he says?  Honestly I have not heard of this being a problem.

Image file formats like JPEG use "lossy" compression; if you "compress"
an image by saving it out as a JPEG then yes, data is lost in the

In programs like Photoshop you can choose the quality setting when you
save an image as a JPEG, and this determines how much data gets thrown
away and how big the resulting JPEG file is.

Your client might mean that he's had to save the images as quite small
JPEG files (hence with some noticeable loss of quality) in order to
successfully email them to you, because of a limitation somewhere on
email attachment size...?

If this is a problem for you, maybe you and your client need to think of
a better way to exchange files. Batching them up and sending a CD or DVD
through the post would be one way. Or use an FTP server?


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