JPEG (old-style) and Flickr

I’m a data geek.

As such, I love digging into things like the EXIF data saved to my photos by my camera.

Flickr has quite a nice (though extraordinarily basic) interface for viewing metadata from uploaded photos.

I love it.

It works quite well.

Except for the way it handles one little tag.

Compression: JPEG (old-style)

I realize that I shouldn’t let this bother me at all, my photos still display properly after all. Unfortunately, I’m just not the type of person who can let this go, so I did a little digging to figure out what made my JPEGs inferior to the presumed “New-Style”.

Flickr is getting this compression information, not from some elaborate algorithm to figure out how the image was encoded, but from a simple flag set in the EXIF metadata.

Compression.

Now, according to the EXIF specification, there is one and only one proper value for this tag.

6

Yes, the number 6.

Oh, sure, there are times when you would want to set this to something else. Like, for instance, when you use some witchcraft to embed JPEG data inside a TIFF wrapper (instead of just embedding a regular JFIF-wrapped JPEG in a TIFF wrapper), you would set this value to 7.

This is the new style of embedding JPEG data in a TIFF.

Since this “New Style” has absolutely nothing to do with how the JPEG itself is encoded, and has no place in JFIF wrapped JPEGs, Flickr’s wording of “(old-style)” to refer to plain old JPEGs seems inappropriate. Simply “JPEG” would seem much more accurate.

 
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