No that won't work. Here what's should/typically happens.
1. You add a product/category photo.
2. If you have checked auto-generate thumbnail in the cat/prod folder when adding the photo, it will generate a thumb based on the size params in your config... such as 150x150. So the system adds two images.
a. The full image in /products/xxxx.jpg
b. The auto-gen thumb image in /products/xxxx_150x150.jpg
3. Then if you turn on the GD system, it should rebuild again the thumbnails, from the product_thumb_image, into a folder called /products/resized/xxxx_150x150.jpg
So why rebuild the thumbnails (not rezised, but actual thumbnail product_thumb_image) using "update jos_vm_product set product_thumb_image = product_full_image"?
Typically you would do this to have your GD library rebuild the RESIZED folder images. You would most likely chose to do this if your product thumb image is 150x150 but you have decided to change the size of your thumbnails to say 250x250.
Since the GD library is using the product_thumb_image to generate new 250x250 images, the images come out bad. Why? Becuase when you first added photos you had it set to 150x150, so the GD library is using a smaller image and trying to BLOW IT UP LARGER.
So what we did was set the product_thumb_images EQUAL to the product_full_image so when the GD library made new 250x250 images in the resized folder, it use the full_image, which is now also the thumb image in the database.
I hope this provides a better understanding of Product_full, Product_thumb, and RESIZED. The problem is that the code for some reason is not pulling form your resized folder, or your gd library is not working to create your resized images, which you can check in your resized folder.
About the only way to revert back to what you had is to
1. Know what your previous resize setting was. (you can check by looking in your product folder! The images are still there)
2. If it was 150 x 150 then you could do something in php to execute a command that replaces xxxx.jpg with xxxx_150x150.jpg for all product thumb images in your database table column product_thumb_image.
I would not do this first. I would
1. Back up my resized folder, then delete it!
2. Browse my website so it forces the GD library to rebuild the thumbs on the fly according to my GD settings... say 250x250.
3. Check my new resized folder to see if the GD library is working and creating 250x250 images for each product.
4. Clear my cache.
5. Revisit my site and see if the code is now pulling from my resized folder.
/product/resized/xxxx_250x250.jpg
Good luck! I will say I have not encountered problems with this until 1.1.4.. something is not kosher.
