Compressing a bunch of images in one go

(I may have asked about this before, I can't recall)

I have A LOT of image files on my computer that are oversized .bmp files created by the method of take a screen shot (print screen), create a bmp file, paste, save. By doing this you end up with 6.7 MB image files, which, if you had saved them as jpg files would be much smaller.

Like a schmuck, I hadn't realized this and I've accumulated a very large number of these oversized files that are now needlessly occupying more space than they ought to.

What I'm wondering is whether there's some image compression software I could use in which you can add a very large number of files into and it compresses them all at once (going down the queue, I mean).

It would also be great if it could replace the uncompressed file with the compressed one, but that's not necessary.

You can try this utility and chose conversion to JPG. http://www.imagebatch.org/

If you want to store all the files into one archive I highly recommended 7-Zip or 7Z for short. Once installed, highlight or press and hold the CTL key and select each file and right click, use the context menu where 7Z is at and chose an archive type. http://www.7-zip.org/7z.html

I gave it a shot, but the thing won't run. Says "side-by-side" configuration is incorrect. (I'm running win 10)

IrfanView also has the batch-convert functionality: http://www.irfanview.com/