What benefit .png over .jpg?

[Joseph Sinclair]

TL;DR,
  If you just want to have an image you can view and you want a smaller file size, then use JPEG and don't edit it.
  If you want to edit the image or it's very small and speed of display is important, use PNG.

The two file formats are quite different:
PNG is *lossless* which means that you can edit, adjust, etc... the file without losing any image data.  It stores all of the data in compressed form, so it's larger, but everything from the original image is still present.
JPEG is *lossy* it actually discards around 90% of the image data, so you can't edit a JPEG without losing some of the image quality; by the third or fourth edit a JPEG gets pretty bad.  It also uses some fairly complex math to store and reconstruct the image, so it's much more computationally intensive to view a JPEG compared to a PNG.
The system (generally) uses PNG for thumbnails because (for small images) PNG is generally faster to create and faster to load due to less computation needed to compress/decompress data versus reconstructing an image from mathematical models.

Hopefully that helps clarify the differences.

On 10/04/2012 03:43 PM, joe at actionline.com wrote:
> What (if anything) is the benefit of .png image files over .jpg image files?
> 
> I can't see any difference in image quality and .png files are 10 times
> (or more) bigger than .jpg files.
> 
> Also, what is the reason or benefit of having hundreds of thumbnail .png
> images in the /home/username/.thumbnails directory?  Is there any reason
> not to delete all those?
> 
> 
> 
> ---------------------------------------------------
> PLUG-discuss mailing list - PLUG-discuss at lists.plug.phoenix.az.us
> To subscribe, unsubscribe, or to change your mail settings:
> http://lists.PLUG.phoenix.az.us/mailman/listinfo/plug-discuss
> 

-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 490 bytes
Desc: OpenPGP digital signature
URL: <http://lists.PLUG.phoenix.az.us/pipermail/plug-discuss/attachments/20121004/bdc7ebac/attachment.pgp>