cana file be JFIF and EXIF compliant at the same time

[rookie1010]

Hello,

can a file be JFIF and EXIF compliant at the same time. My understanding from wiki is the following

The JPEG File Interchange Format (JFIF) is an image file format standard. It is a minimal format for exchanging JPEG files, and uses JPEG Interchange Format compressed image representation. It solves some of JIF's limitations in regard to simple JPEG file interchange. JFIF images are compressed using the techniques in the JPEG standard, so JFIF is sometimes referred to as "JPEG/JFIF". The JFIF meta data resides in the JPEG Application Segment APP0, having the zero-terminated ASCII string "JFIF" as segment header.

Exchangeable image file format (Exif) is a specification for the image file format used by digital cameras. The specification uses the existing JPEG, TIFF Rev. 6.0, and RIFF WAV file formats, with the addition of specific metadata tags. It is not supported in JPEG 2000, PNG, or GIF.


if EXIF adds meta-data tags, then it is a superset of JFIF correct?

 

[QuixoticOne]

It is a superset or extension of JFIF in that a file is still primarily a 'JPEG' image which is viewable in any JPEG viewer I've come across, even ones lacking any EXIF support that I know about. EXIF aware applications will also be able to read and decode the metadata.

I don't know whether EXIF it is an extension to JFIF which is somehow technically incompatible with the JFIF format if you read the letter of the standard, or whether it is just encoded using record / attribute / metadata storage record techniques documented in the original JFIF as being compliant with its specification but whose exact use and interpretation are to be defined by other standards.

Since the result seems in practice to be highly compatible with JFIF viewers I suspect they just used JFIF standardized encoding options to create the storage space for the metadata and then made an EXIF standard to define the interpretation of the JFIF compliant metatdata.

 

[rookie1010]

thanks for the reply, are JFIF and EXIF stored as .jpg, because i am checking out pictures taken by my obile phone cameras and they have the extension .jpg

just checked out the wiki entry for JFIF, and it says

"Formally, the Exif and JFIF standards are incompatible. This is because both specify that their particular application segment (APP0 for JFIF, APP1 for Exif) must be the first in the image file."

however the wiki goes on to say

"In practice, many programs and digital cameras produce files with both application segments included."

i dont understand how both applicatio nsegments can be included since both application segments need to appear first