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It depends <g>. If your audience consists of sophisticated users in big companies that regularly update desktop machines and software, I say go for it. The progressive format paints the jpeg progressively, as the name implies, starting with big fuzzy blobs of color and then coming back and improving the resolution in stages (the number you specify when you save the file). This really only matters for larger images, IMHO, but tastes vary.
If you are creating a site for the great world public, I would stay with baseline, though. Older browsers really do have problems with some JPEGS--older AOL browsers in particular. I'd also try to restrict the number and size of JPEGs in this situation, and keep the quality setting fairly low to accommodate slow modems.
In between those two extremes, use your best judgment. Once you have the site up, you can use WebTrends to find out exactly what browser/platform combinations are visiting your site and in what numbers. If you are willing to ignore the outliers with old browsers (once you have the numbers in front of you), you can always go back and upgrade the images.
---------- Original Message ----------------------------------
From: John Cornellier <cornelli -at- clamart -dot- srpc -dot- slb -dot- com>
>Aside from specifying image compression, Photoshop has 3 JPG file format
* Baseline ("Standard")
* Baseline Optimized
The help says:
What are the pros & cons of each? Surely all browsers in use today support
all formats? Any IE vs. NN issues?