Resize A Batch Of Images
Here's a quick reminder of how to resize a batch of images and adjust the jpeg compression. It's especially useful when preparing images for the web. This method uses the mogrify command, which is part of the imagemagick suite. This is available for Windows and Linux and includes masses of powerful image manipulation stuff.
mogrify -format jpg -quality 70 -resize 620x349 *png
This will output 70% jpeg compression quality. If you specify the same output format as the input files, they will be overwritten.
You can also omit the height of the resized images and they will be scaled automatically, keeping the correct aspect ratio.
mogrify -format jpg -quality 70 -resize 1024 *jpg