Camera RAW - open and save multiple JPEGs, with kb limit, raises the kb size of files below limit

[mojo-risin]

Hi all. Just encountered this issue. I use Bridge and "open in Camera RAW" feature to save multiple JPEGs, with kb limit (100kb). Some of the JPEGs are way below limit and some above, (before the action). So I guessed this feature would only touch the files above specified limit and make them just below limit. But it intereferes with smaller (say 40kb) files also making them 80-90kbs. Is that a bug, or am I missing sth? 

I know I could not select the files below the limit for this action. But for convenience it's easier to select all when You do this a lot. 

[TheDigitalDog]

I suspect this has more to do with the JPEG compression based on the image than anything else. 

For example, save a JPEG at a specific quality setting that's filled with a gray alone. 

Save a complex image, the same pixel dimension. The two will not match anywhere close to each other. 

An image with very high frequency and color detail will not compress the same as one with smooth, fewer colors.