border added to my image

When I upload images to my app there appears to be a white left and top border around the image.
When I upload small images there is no border and the image looks fine.
But when i try to upload large images  say anything in excess of 400 kb or so there is a white left and top border appearing.
I am not able to find out why. Below is the css applied to the div that surrounds the image:
Image

<div class="image">
<img src="image path" alt="image alt"  />
</div>
CSS

.image {padding:4px;text-align:center;}


When I view the image it looks like as  below.
http://img269.imageshack.us/img269/8744/imagesrr.png


Any suggestions to solve this.Thanks

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