Un-embiggening Photoshop JPEGs?

[scott]

I've been scanning some old trip pictures. When I open the 4Mb or so files and tweak them in Photoshop (crop, check levels, a little unsharp mask), the files end up being 3.5 to 4.5 times larger than when I started. Why are the files so big, and how can I get them back to a reasonable size?

[Fat Al]

Did you reconvert them back to JPEG's? Or are they still in PSD format after all the work you done?

[scott]

They're JPEGs.

[Fat Al]

It's hard to say. The other thing I would check is if you've saved them as best quality JPEG's after you finished working with them. But it shouldn't make that much of a difference. Unless if you resized the photos...

[Guest ___]

What about the metadata. When you scanned the images in there was no attached metadata from the scanner, but Photoshop will save metadata to all formats minus "save for web" variant of JPG. Also it depends if you had scanned them in to PS at 8bit, and saved them as 16 or 32 bit, you're going to get a bigger file.

 

Don could give you better tech details as to what PS is actually doing behind the scenes. Also note if you save as a PDF, TIFF, any losless format, or DNG, you'll get larger files as well.

[scott]

I do tend to save them at high quality levels, but I'm not sure how far I can back off on that, especially if that's going to degrade the image without getting rid of whatever's taking up the extra space.

 

I'll check that make sure they aren't saving as 16-bit jpegs. How would I find and/or delete any metadata that the program is adding?

[Guest ___]

you can delete metadata by saving the file "save for web" which strips away all metadata.

[scott]

Oh, OK. I thought maybe there was a program that would remove it.

 

I tried saving the tweaked 4M scans as "save for web" on the high-quality jpeg setting, and they came out about the same as the original size, and without any visible degradation in side-by-side comparisons. So I guess I'll do that from now on.

 

Thanks for the help, guys--this makes a huge difference.