In the ancient times before jpeg every image was uncompressed and huge. In these ancient times hard discs had been much smaller and storage was expensive, so a bunch of smart people sat together and invented a storage format for images to get them a lot smaller without loosing too much image details -> jpeg
For more information I'd suggest a look at theyr homepage http://www.jpeg.org/jpeg/index.html
Sam
----- Original Message ----- From: "Jens Bladt" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Saturday, November 13, 2004 12:52 PM
Subject: RE: Reducing File Size with Photoshop
Noooo... It's 6 040 064 pixel * 24 (colour depth - in bits per pixel) = 144 961 536 bits = 144 961 536/8 = 18 120 192 bytes = 18.12 MB.
I you meant 24 bits/8bits pr byte = 3 (explaining the "3" in your math) - it's fine.
I guess I don't understand what a jpeg compression really does! But you are right - I saved a jpeg file as a tif and then it kept the 18MB size, showing this in the Path Finder. Jens Bladt
mailto:[EMAIL PROTECTED] http://hjem.get2net.dk/bladt
-----Oprindelig meddelelse----- Fra: Sam Jost [mailto:[EMAIL PROTECTED] Sendt: 13. november 2004 12:10 Til: [EMAIL PROTECTED] Emne: Re: Reducing File Size with Photoshop
Can anyone explain: Why is the file size of an *ist D image say 3.936 MB in the Path Finder, and 17,3 MB when opened in PS?
I'd guess 3.936MB is the file size, probably jpeg (compressed) And 17.3 MB is the uncompressed image data for the image (3008x2008x3)
Sam
