This post is of special interest to the mapping community and may be too technical for some researchers.
We digitize all of our images—photographs, maps and text—as TIFF master files, which are processed through our digital preservation system and preserved in our secure digital storage. We have been making all our digitized images available to researchers in our online search in JPG format. It allows us to make high-resolution files available in a fairly small size so they can be opened and viewed quickly. The quality is good enough for most uses.
Clicking on this map image will bring up the high-resolution JPG version, which can then be downloaded. Note the usual descriptive metadata below the image.
The mapping community has told us that JPG files are not good enough for their use. TIF or PNG formats give the best results when manipulating files in mapping software. The original scanned files, without any compression artifacts, would be the most useful.
To support the use and re-use of these valuable resources by everyone, we’re making losslessly compressed versions of the original TIFFs of our scanned maps available for download. We’ve added a link to the TIFF of a map to our online search as part of the descriptive record for that map.
Scroll down the description to find the link to the TIFF on the City’s FTP site.
So that you can verify that the file downloaded correctly and completely, we’ve included the full file size and the MD5 checksum.
We’d like to thank City Information Technology, whose recent upgrade of the City’s FTP site made it possible for us to make the files available this way.
It was a day just like any other at the City Archives. Archivists and researchers spoke in whispers as they gently leafed through decades-old memoranda and Kodachrome photographs. Just then, at the front desk, a mysterious stranger appeared with a hard drive and a look that said she wanted to donate it. When she couldn’t answer how much data was on the drive or how it was formatted, it was clear that this day would not be normal after all and… it would not be easy.
Examples of digital storage media - Photo by Danny Nicholson, CC BY-ND 2.0 (http://www.flickr.com/photos/dannynic/6282154645/sizes/z/in/photostream/)
Archives Manager Heather Gordon likes to say that being an archivist is like “playing detective”. There has always been an aspect of detective work in what archivists do—from digging through boxes left abandoned in a garage searching for records to helping researchers find the documentation that helps them accomplish their work. In the age of digital acquisitions, her statement couldn’t be more true. Unlike their physical analogue counterparts, donations that come to us in folders on digital media can’t be easily leafed through and assessed at first glance. Those folders and their contents are made of bits that don’t have meaning without some kind of hardware and/or software intermediary. Continue reading