Thumbnail Cache
Definition
A store of small preview images generated by the OS or applications when media is first viewed. On Android the primary cache is stored in a .thumbnails directory or a MediaStore database; on iOS thumbnails are managed by the Photos framework in DCIM and PhotoData directories. Caches are evicted on their own schedule, independent of source file deletion.
- Android store
- .thumbnails directory or the MediaStore database
- iOS store
- Photos framework, DCIM and PhotoData directories
- Eviction
- Independent schedule, not tied to source file deletion
- Domain
- Mobile device forensic recovery
Common questions
Why does a thumbnail cache matter after the original photo is deleted?+
Because the cache is evicted on its own schedule, a thumbnail can survive well after the source image file and its MediaStore or Photos database entry are gone, giving an examiner low-resolution proof that an image once existed on the device.
Can a surviving thumbnail alone prove when a photo was taken?+
Not reliably. The thumbnail's own timestamp usually reflects when it was generated or last accessed, not the original capture time, so it needs corroboration from other artefacts such as EXIF data or database records before a capture date is claimed.
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