Go to Google.com and select "images"

Type in the description of the image you want to find.

Click on the "search tools" button then "size" then "Larger than"

Select size "2MP or larger"

Click on an image you like, then select "view original image"

If you can't find an image you like in that size, you can go down to "1024 x 768" under the "image size" drop down menu.