Why photos taken on a modern device may appear rotated incorrectly:
Originally written as an explainiation for my Precalculus teacher as to why student's work render incorrectly in Google Classroom.
Image metadata (EXIF)
Exchangeable image file format (officially Exif, according to JEIDA/JEITA/CIPA specifications) is a standard which allows for metadata to be stored in an image or audio file.
This is important, as it can store information about the image besides the image itself. Common applications include things such as date taken, shutter speed, camera type, or location, however any aribtrary key and value may be stored.
A few keys are required, such as the use of the Discrete Cosine Transformation (DCT) on
image/jpeg files, various algorithms and codecs used for processing RIFF files such as
A photo taken on a modern device, such as an iPhone or similar, can contain dozens if not hundreds of these tags, however those found in most images are things such as bit depth, colour palette,