Webview or Originale image

I am adjusting the weight of the images and, checking via ftp, I saw that in each folder in wp-content / flagallery / there are 3 versions of the images.
One – I assume it is the original – in the main folder of the gallery. Then two folders “thumbs” (with obviously the thumbnails of the images at the chosen size) and “webview” which contains an exact copy of the original images.
I wanted confirmation of being able to delete and / or archive elsewhere, the original copy of the images leaving only the two folders “thumbs” and “webview”. I assume that those necessary for the operation of the gallery are those created by the plugin itself.
Can you confirm that for me.
Thank you