Monthly Archives: July 2013

TIFF/EP vs. Exif

I just discovered today that there are two different TIFF tags called “FocalPlaneResolutionUnit.” Tag 41488 goes by this name and is part of the Exif tag set. Accepted values for it are:

  • 1 = No absolute unit of measurement
  • 2 = Inch
  • 3 = Centimeter

Tag 37392 is a TIFF/EP (Electronic Photography) tag (working draft, final version not available online), also used in other raw formats, including DNG. Its accepted values are:

  • 1 = Inch
  • 2 = Metre
  • 3 = Centimetre
  • 4 = Millimetre
  • 5 = Micrometre

Recently I was sent a TIFF file, as a JHOVE issue, that had a tag 41488 with a value of 4. JHOVE correctly, but perhaps confusingly, reported that the fFocalPlaneResolutionUnit tag had an invalid value.

There are other tags in TIFF/EP that are equivalent, or nearly, to Exif tags. In some cases their values are identically specified, sometimes not. The Exif SubjectLocation tag is numbered 41492 and always has two shorts for its value, giving an X and Y value. The TIFF/EP counterpart is tag 37396, which can also have three shorts (specifying a circle) or four (specifying a rectangle).

I don’t know how this came about, but it’s something to watch out for in software that deals with both Exif and TIFF/EP tags. Some software may accept the EP extensions for Exif tags, but there’s no guarantee this will work.

When the Internet Archive gets a National Security Letter

This post is off topic for this blog, so ignore it if you like. A number of people connected with archives and preservation activities read this, though, and I think it’s important for people to know that the Internet Archive was subjected to a National Security Letter and successfully fought it, thus becoming one of the very few recipients of these Orwellian orders to be allowed to talk about it. Please read the article.

The FBI has issued tens of thousands of National Security Letters. If you’re the target of one, you can’t tell anyone, not even your own family. The Patriot Act originally prohibited people from even talking to a lawyer about them, but that ban was struck down. I have never been issued a National Security Letter, so I can tell you I haven’t. If I had been, I couldn’t say anything, and if you asked me, I’d have to say, “I can’t answer that.”

Google Reader is gone (yawn)

feedAs of today, Google Reader is gone. (Correction: It goes away at the end of today. You still have time to export your feed list.) When its termination was announced, some writers declared it meant the end of RSS feeds. From what I’m seeing today, the attempts at panic have died away, replaced by a realization that RSS and Atom are well-understood feed formats and that lots of alternatives exist. Tristan Louis writes for Forbes:

While the death of the most popular RSS reader on the internet could have been seen as something that would represent a grave danger for RSS as a standard, for openness as a concept, and for heavy news consumption, the inverse has been true, as it only solidified RSS’ position in the world as the format for news delivery. Reader was a good product but one can hardly call it a great product and its demise will help rectify some imbalances it created in the market.

Hopefully dedicated users backed up their feed collections as an OPML file. If not, all they have to do is start collecting feed URLs again.

There’s no need to use a website at all to manage your feeds. On my iPod, I use Free RSS Reader, a simple, straightforward reader, though unfortunately it’s no longer being updated. On my main computer I use Sage, a Firefox extension.

A few columnists got a temporary boost in readership and a long-term loss in credibility by proclaiming the demise of RSS. The rest of us are still fine.