I have just changed the theme on my blog, and because of a small page width, it breaks the layout. Most of my earlier images (attached in posts) are around 600px in width, and now I need to resize all of them them proportionately to 450px. How do I resize them all at one shot? Is there a plugin for this?
P.S.: Writing a CSS rule is a good option, and I’ve already done that. But I figure resizing the images would also knock off the download overhead for each page!
I asked a similar but broader question, and I still need to research and write a complete answer. In the meantime here are some pointers that might help you:
I wrote a set of plugins that resizes all images to the size used in the editor. It works by converting <img src="https://wordpress.stackexchange.com/questions/4984/image.jpg" width="200" height="400"/> to <img src="https://wordpress.stackexchange.com/questions/4984/image-200x400.jpg" width="200" height="400"/> (Resize img tags) and catching and generating those missing intermediate sizes on request (On-Demand Resizer). You should be able to do the first part in bulk, and then let the second plugin handle the new images. It also works with partial information: image-200x.jpg will return a proportionally-resized image 200 pixels wide.
Regenerate Thumbnails indeed re-creates images at different sizes, but I don’t think it also updates your post content to refer to these images? Even worse, if it deletes the old intermediate sizes, your post will still reference the now non-existing image-600x400.jpg instead of image-450x300.jpg.
