The Philadelphia Contributionship
The Philadelphia Contributionship Digital Archives

The Philadelphia
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Help: Viewing Images


Images in the Contributionship Digital Archives are stored in a highly compressed, high resolution format that facilitates quick delivery of quality images to your browser. Depending on your software, there are two different ways we provide access to the images. Please find the appropriate section below for some instructions on viewing the images in the archives.

In terms of technical details, the images are stored in ER Mapper's ECW (Enhanced Compression Wavelet) format, a standard very similar to JPEG 2000. High compression ratios permit a 40 MB original scan to be stored and delivered in just 2 MB.

Using the Image Viewer

Below is a description of the toolbar buttons provided and how to use them:

The hand tool allows you to pan or roam around the image. When this tool is selected, click and hold anywhere on the image and drag it around as desired.
The zoom tool allows you to click and drag on the image to zoom in and out. Click and drag down to zoom in. Click and drag up to zoom out.
The zoom box tool lets you draw a box on the image to zoom in.
Click the fit image width button to display the full width of the image in the viewer.
Click the full image button to display the entire image in the viewer.

ECW Viewer Plug-in

The best (and fastest) way to view images in Microsoft Internet Explorer or Mozilla Firefox (running on a Windows operating system, such as Windows XP) is to download the ECW viewer plug-in. This plug-in is freely available, and can be downloaded from our site.

On most recent browsers, you can also view the images without a plug-in using a JavaScript interface similar to Google or Yahoo! Maps. You get the same functionality, but images refresh more slowly than with the plug-in. To view images without a plug-in, you don't need to do anything -- it should just work. (If you're having trouble, please read the compatibility and troubleshooting information linked below.)

  • Download the ECW plug-in
  • View browser compatibility and troubleshooting information