I think I know what your talking about.
When I have nice big clear pics of my car (on my computer) and then I post them here, they get a little fuzzy.
When you use the "attach files" function here to load your pics, they will get resized and then you loose some of the definition.
I used to get around this by hosting my pics on photobucket and then using a direct link to my pics there.
But now I think photobucket has started "resizing" photos that you store there too, cause when I look at them there, or after linking to them here, they look a little fuzzy.
I need to find a new photo hosting website that doesn't automatically resize your photos.