When you upload image, WordPress will scale crop it to many different sizes.
If you're not happy with the auto-crops, use this plugin to upload alternative image..
If you have images showing up in your theme already, there's nothing you need to do after activating this plugin.
This plugin will add metabox to every post type and allow you to modify every image size.
No support will be provided by the developer..
Down below, in Image Override metabox, upload image for one of the sizes, and save the post...
Any function you're currently using to display the image ) will now display the image if the override is applied to that size...
The following people have contributed to this plugin..
Browse the code, check out SVN repository, or subscribe to the development log by RSS...
Fixed issue if you use array for the image size.
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