What is a THUMBNAILS File Type?
You can navigate to the THUMBNAILS folder on an Android device using a file manager. You must, however, make sure that your system displays the system and the files hidden in the settings.
The larger the file THUMBDATA3-1967290299 and THUMBDATA3-1763508120, the more you have pictures in the application Gallery. It can become several hundreds of Mo or, in some cases, several GB if you have a large number of miniature images in your Galerie application. Each time a new image is added, and even when an image is deleted, the indexed properties of the image remain.
To reduce the size of THUMBDATA3-1967290299 and THUMBDATA3-1763508120 you must delete the images of l' application Gallery then delete THUMBDATA3-1967290299 and THUMBDATA3-1763508120. The files will be regenerated by the Gallery application but only for images currently stored in the application.