What is Picasa’s “Unique Id,” and does it correspond to EXIF ImageUniqueID?
Asked 5/24/2013
4 views
2 answers
0
Picasa shows a property called “Unique Id” in its Properties list. EXIF also defines a tag named ImageUniqueID, but some metadata tools don’t display it in my files. Is Picasa’s value the EXIF ImageUniqueID tag, or is it something Picasa generates itself? If it is stored in metadata, what does that EXIF field represent?
Originally by Photography Stack Exchange contributor. Source · Licensed CC BY-SA 4.0
Photography Stack Exchange contributor
13y ago
2 Answers
2
It is in the exif specification:
http://www.exiv2.org/tags.html
0xa420 42016 Photo Exif.Photo.ImageUniqueID Ascii This tag indicates an identifier assigned uniquely to each image. It is recorded as an ASCII string equivalent to hexadecimal notation and 128-bit fixed length.
It is based on the timestamp and camera serial number, in an encryption manner.
Originally by user11455. Source · Licensed CC BY-SA 4.0
user11455
13y ago
0
Generated from our catalog & community — verify before relying on it.
Picasa’s “Unique Id” most likely refers to the EXIF tag ImageUniqueID. That tag is part of the EXIF specification and is defined as a 128-bit identifier stored as an ASCII hexadecimal string.
In EXIF references, it appears as tag 0xA420 (Exif.Photo.ImageUniqueID). The purpose of the field is to uniquely identify an image.
Based on the provided answer, this identifier is intended to be derived from information such as the timestamp and camera serial number, using an encoded/encrypted method.
If some tools do not show it, that usually means either:
- the file does not actually contain the tag, or
- the tool/library you tried is not exposing that particular EXIF field.
So the best-supported conclusion here is that Picasa is displaying the EXIF ImageUniqueID field when present, rather than inventing its own unrelated “Unique Id.”
Recommended products
UniqueBot
AI13y ago
Your Answer
Related Questions
Can Picasa automatically move photos into date-based folders without losing face tags?
What does the EXIF "Image Unique ID" field mean, and what is it used for?
What does the EXIF “Gain Control” tag mean?
Is a lens’s stated focal length a physical property, or a 35mm-equivalent value?
What does a fractional color bit depth like 23.5 bits mean on camera comparison sites?