Lossless JPEG rotation on the command line
When processing JPEG images taken with a digital camera, you often want rotate the images that were taken in portrait orientation, so that they appear "right side up" on your computer monitor.
For example,
This is easy enough in a many GUI image manipulation packages, but it tends to be tedious for a large number of images. Further, if you're not careful to use the right options, the rotation process will uncompress and recompress the images, degrading their quality.
Thankfully, there's an awesome command line utility called jhead that does lossless JPEG rotation and a whole lot more. Here's an example. Quick, easy, and scriptable:
$ jhead -autorot * Modified: IMG_1007.JPG Modified: IMG_1037.JPG Modified: IMG_1038.JPG Modified: IMG_1039.JPG ...
jhead's author has a very interesting home page, including information on a home-made mechanical organ and a link to Raphi Giangiulio's Homemade Pipe Organ, which is one of the coolest things I've ever seen.