Hi

I was wondering what is best, using jpg or png images when constructing a website for faster site download times for the end user?

It depends the usage of the pictures.
JPG images are smaller, because compressed with a destructive algorithm (the smaller they are, the more flacky they look).
PNG images are bigger, but can contain an alpha layer (with x% transparency) and use an non destructive algorithm.

I tend to use PNG for pictos or icons and technical diagrams, as I tend to want a clean, sharp image in those cases.
But I stay on JPG for the rest.

Thanks for your reply tripy sounds logical to me.

ps. But what difference will a alpha layer make?

IE 6 and below is incapable of displaying alpha transparency on PNGs.

Originally Posted by LadynRed

IE 6 and below is incapable of displaying alpha transparency on PNGs.

Yes (with a reserve, but you know what I'm thinking about), and I have as a rule of thumbs that I develop programs for actual technologies.
If peoples insist by using outdated products, then they can support minor visual glitches.

At the same time, I work for myself, and I'm not bound to any customer wanting to see a site in his browser like he see it in photoshop.
And when I receive complaints, I sent them to the firefox download page.

After that, if they don't want to upgrade, it's not my problem anymore. Period.

Originally Posted by alert2media.com

But what difference will a alpha layer make?

An alpha layer allows you to specify how much translucent you want your image to be. GIF don't allow that, you have 256 colors, and 1 is 100% translucent.
PNG allows you to specify with more granularity the translucency, and it support 32bits colors format, where gif are limited to 8bits

I'd say neither. A GIF is better for most web graphics when compared to a JPG especially for filesizes (aka fast downloading). Like stated above a PNG is good for stuff stated.

Good luck !

Hello -

I have taught Photoshop for a number of years, at local colleges, and I have to say that you should weigh the features and benefits of each format before you make a final decision.

It is NOT TRUE that JPEGS are always smaller than PNGs (there are varying degrees of compression which may be set). But it is true that JPEGS have more colors available in them than either GIFs (maximum 256) or 8 bit PNG's. You can check that out in the "Save for Web" dialog box in Photoshop. See the article: Gif, JPEG, or PNG?

Best -
Scott