Broken image? Need to understand..

I need to understand this with product images..

Lets say that i create a new product with NO image.
Upload image (002590.jpg) via FTP to "image/catalog/product" <- This is the right folder, right?

I update DB, oc_product > image > with the right img location like "catalog/product/002590.jpg" <- all my other image who is uploaded via admin have this location so i think this is right?

The result is a broken image?
I want to understand it this way because i am making my own img upload script.

Thanks / Ante

Add one via the admin to another project and then look and see how it's stored - that will show you the right way.

Hm, i dont get it..
So, the "system" creats 228x228 & 500x500 image and place them in the cache folder? Thats it?
The entries in the DB looks exactly the same as other products rocording to the "main" image to the product.

Is there more parameters that i am missing?...