Does Android keep deleted photos and images from the phone? I heard from a friend that android phones can trace deleted photos and images and videos back even after deleting.  Is that true?

If so, how can it keep things there unseen until a technician finds out in service centre?

Thanks in advance.
It is very basic when you try to understand the current digital storage techniques.

Deletion is not actually deletion on any OS, it would be far to demanding on the CPU if a full change from 1 to 0 was made on every single sector, therefore the computer just registers the area as reusable.. 

The next operation to copy onto that area will technically do the deletion ( sort of )  



Think in all 1's &amp; 0's with me for a second here >_&lt; 

Let's just say hypothetically your image looked like this in binary ( computer language )   

1001001001001001001001001


To erase the image, your CPU would need to write 0 over all the sectors ( Secure Delete )... Let's say that each change from either a 1 or a 0 to a 0 will take 1 second... that's 25 seconds to delete that image.. 

Now let's look at how a computer handles this consumption...

Instead of taking 25 seconds to write nothing over the sectors, it could just mark these sectors as writeable... 

Instead of 25 seconds to wite nothing + 25 seconds to wite a new same size file to the same area... It could just skip the first write ( 25 seconds ) and half the time by just overwriting instead of rewriting...

A full ( Double Cycle ) rewrite would consume twice the CPU for every single delete and write... 

Therefore, computers do not "DELETE" so-to-speak.

The idea is all based on older Computers, The founding machines if you want .. 

The founding machines are alot slower than modern computers and maybe some time soon this will be addressed...

To, Un Delete is not to UnDelete, As Delete is not to Delete... 

Un Deleting is marking that area on the storage as Used again.. Meaning the computer knows the file exisrs their and it is not replaceable. 

...

Dispite all of this, Android ( since 5.0+ ) now actually keeps your picture's in a hidden folder after deleting, you don't need to do a Sector Scan to find the files marked for replacement... Instead you can see the deleted image's very easily... 

This is partly in my opinion due to Law Enforcement Agencies wanting easier access to deleted photos for the obvious reasons...

Ok so want to test what is findable on your phone ? 

Run this program called Disk Digger from Google Play...
Disk Digger - Photo Edition Non Root (folder scan) - FREE

Disk Digger - Root ( full sector scan ) - PAID