Image Cropping

I am looking for an tool that allow user crop the upload image in a given frame size.

I saw this somewhere, but just don't remember any more. It works like this: user upload an image, then on the second page, there is a frame mask (div) cover up that image, the image is fade out, but the frame part is clear. Then, user can move the mask any where above the image, once user select the prefer area, he can crop the image off, the final cropped image is size of that frame.

Does any know this image cropping application?

Thanks

Tony