Does .zip archive re-compress JPEG?

This just crossed my mind, are you compresssing your jpeg files again, and thus adding more artifacts, by putting a folder of images into a .zip file?


experts? aye or nay.

No; zip compression does not alterr the image data.

Nor does zipping JPGs save any appreciable space as JPGs are already highly compressed. I receive batches of 10-20 zipped JPGs by email from my company's field photographers every day. It doesn't save space, but it does make attaching 20 photos to an email message much easier.

The new Winzip12 Pro claims to be able to compress jpg.

JPEG Compression
WinZip now compresses your JPEG files — digital photos or graphic images — by 20 to 25%, without any loss of photo quality or data integrity. Now you can send photos faster or fit more on your hard drive and removable media than ever before.

http://www.corel.com …Tabview=tab1&ta​bview=tab1

Car2n wrote in post #7681477
The new Winzip12 Pro claims to be able to compress jpg.

Yeah... I still don't find that significant. And it's a moot discussion for me as my output is TIFs! My office sends TIFs, Illustrator and Quark files to our printer via FTP... no concern about compression.

Ok, cool beans.