If there is an image named the same and in the location that the scraper wants to place an image it won’t overwrite it. It will just add the file name to the XML file.
The default location is
./images/<rom name>-image.jpg and ./images/<rom name>-thumb.jpg
(Although -thumb isn’t used by ES so probably should disable it.)
There are several flags to adjust where and how images are handled that you can see with scraper -h
but these 3 are relevant:
-image_suffix, -img_format, -no_thumb
-image_suffix controls the text appended to the end of the rom name and defaults to -image like ES was doing.
-img_format controls the file type to save images as and defaults to .jpg so if you have png you can switch it
-no_thumb tells the scraper to not bother with the thumbnail image since it isn’t used and you don’t want the scraper to download a thumbnail from the external source.