Chapter twenty. Generating Data-Driven Graphics

MANY PEOPLE USE PHOTOSHOP TO PROCESS one document at a time. When creating groups of files that share common elements, such as a stack of baseball cards, the usual approach is to design a document, make copies of it, and manually edit the text information and images for each player. With Photoshop CS2, there's a more automatic way to generate groups of documents that use the same layout but have different images and text. That way involves variables, placeholders in a file that maintain position but contain contents that can be swapped out automatically by Photoshop from a defined set of images or text. Think of it as similar to a mail merge between a mailing list and a word processor, but more visually interesting.

Data-driven graphics require a template, variables, and a data set. You design a template in Photoshop using layers as variables that can contain text or graphics and define the names of the variables. In an external file, you set up a data set of text and graphics that uses names that correspond to the variables. Photoshop takes the template document and makes copies of it, and in each copy Photoshop inserts a different instance of the data to replace each variable in the document. In the end, you get a complete set of documents filled in with unique combinations of text and graphic data.

Using variables doesn't save very much time on a short run of similar documents, such as a set of posters promoting the five plays in a theater company's season. However, in the previously mentioned example of baseball cards, variables can save great amounts of time and easily maintain consistency across documents, because hundreds of documents are involved. Using variables also saves time when the data is already available in a database or spreadsheet program, because Photoshop can import the commonly used tab-delimited or comma-delimited text files that you can export from a database or spreadsheet.

In some cases it may be better to generate data-driven layouts using a dedicated layout program such as Adobe InDesign. But if producing Photoshop files is a more direct route to a final image format such as JPEG for the Web, Photoshop may be a more straightforward alternative.