Save As to reduce file size

[Doug_Katz@adobeforums.com]

I make an illustration and save it. The AICS file is now, let's say, 200KB.

I reopen, add a file-enlarging element (brush strokes, a gradient mesh, an effect, or
some such) and resave. The file understandably becomes 400KB, give or take.

I reopen again, delete the file-enlarging element and resave. The file remains at
400KB.

I reopen and Save As (with the same or a different name). The new (or overwritten)
file returns to its former svelte 200KB.

I remember this kind of phenomenon with PageMaker many years ago. And old
versions of FreeHand. What is happening with a save as that doesn't happen with
a simple save? It's obviously "purging" something... but didn't I purge that same
something by deleting the element that accounted for the bloat in the first place?

Thanks.

[Scott_Weichert@adobeforums.com]

It's because Illustrator does a kind of "fast save" when you save an already saved document. Changes get written to the end of the file rather than rewriting the entire file. Save As forces Illustrator to rewrite everything, which in turn will reduce the file's size. I always do a Save As when i'm finished with a file.

[Doug_Katz@adobeforums.com]

Hmm. So it does exactly the same thing, exactly the same way, and for
exactly the same reasons as the oldtime versions of PageMaker back in
the day. But Scott, Photoshop doesn't operate this way, does it? I seem
always to reduce file size with a normal save in PS when, for example, I
trash a layer, or apply the Blur filter, or convert to grayscale or some such.
And how 'bout InDesign (which I don't own)? Does that benefit from a
Save As at the end of the day?

[Scott_Weichert@adobeforums.com]

Photoshop doesn't. Indesign does benefit from save as.

[Wade_Zimmerman@adobeforums.com]

Different type of content no?

[Doug_Katz@adobeforums.com]

Got it.