Preventing main product image enlargement from smaller source image

Hello,

Using nop1.5 we are moving an old site to nop which already has all images from the previous cart. When we use the largest product images we have and the image is smaller than the main image size of 300pix then nop makes the image larger from a smaller source image of let's say 200 pix high.  This makes the main image fuzzy. Is there a way to prevent image enlargement when the source image is smaller than the main image?

Thanks,
Jorg

you can set the image size in admin  - > configuration --> global settings   under the 'media' tab

Thanks for the reply. What what I am trying to set up is that when a source image is smaller than the large size image, that the source image doesn't get enlarged but stays its original size avoiding a fuzzy large image. Some of the source images are only 200pix high and then get enlarged to 300pix high (which is the desired image size). So if there is a setting that would state some thing like 'do not enlarge images' then my 200pix source image would be still 200pix high in the main 300pix image area, but it would stay sharp.

Thanks,
Jorg