Memory Consumed by Gallery is more that the data :
A user might now be aware about the new feature "Trash" in Gallery. This lets you recover the accidently deleted images & videos.
In models like G6 & Q6, TRASH option in provided in the Gallery which will retain all your images & videos after being deleted
from the Gallery. The retained images will remain in TRASH for 7 days & till then can moved back to Gallery.
TRASH will however use the same internal memory of the phone & may fill the space of the phone.
To free the memory you can empty the trash.