At least I have now found a conversion method for tiff to jpeg on OSX that doesn't involve starting PhotoShop; it seems that the preview tool can save things in many formats. Saves me some time. I still wish that grab would generate jpegs by default. People have tried to convince me that this is possible on OSX, but I have had little success until today. It took me a while to decipher these threads in the mac osx hints forums:
The proposed method of setting the default screen capture appears to have no effect on the format of the images grabbed my grab on OSX 10.5.6:
However I think it may have affected the built in screen capture system which I previously been unaware of. Keyboard shortcuts ShiftCommand3 or ShiftCommand4, dumps the entire screen or selection, respectively, to a file on the desktop. Since setting the defaults these appear to be in jpeg by default. Now that's a huge step forward. Instead of starting grab, grabbing, saving as tiff, opening Photoshop, converting to jpeg, I can now just hit ShiftCommand4 - grab the area I need and then hit the image link button in blogger and upload the image. That is going to save me loads of time! Would be nice if I could rename the file in the file selection window that my browser pops up ...
samuel-josephs-computer-2:test samueljoseph$ defaults write com.apple.screencapture type jpeg
samuel-josephs-computer-2:test samueljoseph$ defaults read com.apple.screencapture
type = jpeg;