Ok, I'm not sure this change happened in High Sierra or possibly a previous version. I just upgraded from Yosemite to HS and just noticed a change in the Grab App that I was very happy to see! Before I upgraded, when I would do a screen capture with Grab APP, the files would always be captured at a .TIFF file! This is something I've seen many people complain about over the years.
Well, I just did a screen capture with Grab and when I went to save the file, I noticed it was already a .Jpeg! Woo hoo!
Well, I just did a screen capture with Grab and when I went to save the file, I noticed it was already a .Jpeg! Woo hoo!