I'm attempting to re-size and crop submitted image while exhibiting as ad banners in wordpress. I attempted using theImage wordpress plugin and image-re-size plug ins. But they are not effective not surprisingly. If the image is 1024x800, I wish to fit it within 940x138 canvas. Image should re-size up to 940px and crop up and down from center. If the image is of 900x1200, then your image shouldn't have to re-size but crop up and down.

Try considering the media configurations page in your soul dashboard (yourdomain.com/wordpress-admin/options-media.php). You place the max width and height for every image size: thumbnail, medium, and enormous.