optimized "creates smaller but less compatible files"

What does this actually do?
It's a checkbox located in the Save for Web dialogue of ImageReady, Photoshop, Elements etc.

In article ,
wrote:

What does this actually do?
It's a checkbox located in the Save for Web dialogue of ImageReady, Photoshop, Elements etc.

It creates a JPEG file whose contents are designed for maximum compression. Specifically, it rearranges the quantization table for maximum compression.

The technical details of what this means are fairly complex, but in practice it means that it creates a smaller JPEG that certain very, very, very old programs can not read reliably. For example, I believe the first version of the NCSA Mosaic Web browser, written in 1992 and released in 1993, can't read an optimized JPEG. (Of course, it can't read tables, frames, background images, or forms, either.)

Any Web browser or other program released after late 1993, including all current major Web browsers without exception, have no difficulty with optimized JPEGs. You have to search pretty hard these days to find a program that can not read an optimized JPEG.

--
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com

ok, cool, thanks. i figure, then, it's just extra compression on top of the jpeg compression that's already there in the other settings - "quality" etc?

In article ,
wrote:

ok, cool, thanks. i figure, then, it's just extra compression on top of the jpeg compression that's already there in the other settings - "quality" etc?

That's one way to think of it, yes.

--
Art, photography, shareware, polyamory, literature, kink: all at http://www.xeromag.com/franklin.html
Nanohazard, Geek shirts, and more: http://www.villaintees.com

"tacit" wrote in message

In article ,
wrote:

ok, cool, thanks. i figure, then, it's just extra compression on top of the jpeg compression that's already there in the other settings - "quality" etc?

That's one way to think of it, yes.

If you use 2 up and look at both images you can compare the quality also is a little box in the bottom of that frame showing download time and or file size difference from the original.