TECHNICAL DETAILS

PVPhotobase grew out of two of the original goals of the Pascack Valley History Project. The first was to begin making digital copies of all historically significant photos, documents, maps, artwork, and other 'flat' materials in the Pascack Valley. Paper is very fragile and subject to destruction by fire, water, mold, and simple aging. Having a digital copy of a historic photo lets us recreate it with reasonable accuracy if the original is lost or destroyed. The second goal was to make history more accessible to the members of the community. The vast majority of the historical photos and other material is locked up in local museums or in peoples attics or basements and is rarely seen by anyone. The idea of an online database that would make this material available 24x7 for anyone to view was attractive from the outset.

Some of the collections were were given were already scanned and we were provided discs with the JPG files. The resolution at which the scans were made varies and some are more viable as digital backups than others, although all are quite adequate for online viewing.. Wherever possible we try to get originals so that we can do the digitizing at higher resolutions.

DIGITIZING

We do not scan images in the traditional sense with a flatbed scanner. Given the number of images we are hoping to acquire this would be an impossibly time consuming task. Instead we use a high resolution digital camera on a copy stand to photograph the material. This allows us to capture many images in the time that a single scan might take.

Initially we used a Canon D30 camera with 3.1 megapixels. Two years ago we upgraded to an 8 megapixel Canon 20D, and recently we moved up to a Canon 40D with 10 megapixels. Bear in mind that these are high end digital SLR cameras with large imaging chips that are approximately the size of a 35 mm slide. The produce a much clearer image that the 1/4" chips in even the most recent 10 megapixel point and shoot cameras. The lenses are also far superior which adds to the quality.

We shoot primarily with two Canon 550EX strobes slaved together and illuminating the originals at a 45 degree angle. This eliminates reflections from any flat original. Old books that don't lie flat present a problem and we are working on a solution for that situation.

Cameras don't allow you to set a DPI in the way that scanners do. The image is a fixed number of pixels, in the case of the 10 megapixel camera approximatelt 3800 x 2600. What this means is that the effective DPI is a function of the size of the original. A 10 x 8 inch original will be digitized at roughly 380 DPI. 3800 pixels across 10 inches is 380 per inch. A 5 x 4 original will yield an image with 760 DPI. In effect we can get a 760 DPI scan in a fraction of a second using the camera as opposed to a minute or so on a scanner at that resolution. Where this becomes a problem is with very large originals. We have tried shooting broadsheet newspapers which are 30 inches long. The resulting image is only at 125 DPI which when converted to a PDF file is hard to read. We're working on it. But most of what we work on is small so we are in good shape.

Once the images are shot we bring them into Photoshop and crop any unused space around the image and convert black and white images to grayscale. Other than that we do nothing to the oiriginal camera shots. We copy the batch of hi-res files and then rename them with a coded file name that uniquely identifies the collection. We then copy set of files again to make a new set that we prepare for the online database by reducing the size to a maximum dimension of 1200 pixels. We also color and contrast balance and do a few other things to the low-res files to make the online image as viewable as possible.

We upload the files onto the web server and then import them into the photobase using the custom database software that the system is based on.

SOFTWARE

The PVPhotobase runs on a software package called Photos that was written by a Colorado based photographer and programmer named Alex King. Alex wrote it to handle his own photos and in its original form it has many features that don't apply in our application. We do not need to store detailed information about the camera, exposure, and so forth. We also cannot use the date functions because they require a full month-day-year format. With historical photos we are lucky if we can identify a decade when the photo was taken.

To make Photos usable in our environment we had to do a lot of 'hacking' to remove functionality we didn't need and to modify other functions to work the way we needed them. We also had to create a read-only non-destructive version for the public to use. All of this took many months of programming and testing and it was only in late 2007 that we finally had a software version that was appropriate for public release.

The program is written in PHP and HTML and uses a MySQL database to house the data and thumbnail versions of the photos. When it displays larger sizes of images it refers to the files that we have uploaded. Because the database is stored in an industry standard format we can access the data with a number of other utility programs that allow us to make large scale batch changes or move data between fields for large groups of images.

So that's how all of this works. We continue to work on the software adding features and improving functionality as we go. But with a smoothly functioning search interface, an industry standard database and 3000 images in the PVPhotobase it is becomming an impressive history tool for the Pascack Valley.

Technical questions or suggestions for improvements or additions? We'd love to hear them. Just email us at nbarber@pvhistory.org

NB