I’ve been using Tableau for a couple of quality improvement projects in hand hygiene monitoring and telemedicine, and I recently presented some preliminary data at a recent intramural research conference. One of the challenges I had when using Tableau was to export the charts at a resolution suited for high-quality printing (a pixelated chart in a poster is like a car crash…can’t stop looking at it!). If you use Scribus, or another professional desktop publishing application to create your poster, it will tell you when your graphic assets have a low resolution for printing.
So far, Tableau does not have the chance to export a sheet or dashboard in a high-quality format (EPS or TIFF). What is the most popular hack? You export it as a PDF file, then you open it with your favorite PDF reader, and then you take a screenshot (which is usually saved in a PNG format). You try zooming in the PDF as much as you can before the screenshot. Have you noticed that the resolution is maintained when zooming in? The reason for this is that the graph is stored as a scalable chart (like SVG), not as a bitmap. Unfortunately, the resolution from the screenshot is not that great if you are planning to print a 72×48′ poster.
Here’s a solution: Open the PDF file with GIMP. You import the file as “image” and you enter the desired resolution (300ppi or more), and the canvas of a predetermined size based on the desired resolution is created. If you want to use just a part of the imported image, you can select it with the rectangular selection tool, then right click and open Image>Crop to selection. The canvas is reduced in size to the selected area. After uploading an exported chart from Tableau in PDF format in GIMP, the canvas is cropped to the selected area. After this, you export the graph in the desired format. This method takes more steps, but you will be rewarded with a high-quality image for your poster.
Tableau should add the option to export sheets and dashboards to high-resolution image files. It will help increase its appeal as a tool in academic medicine. For a more extensive discussion, this blog entry from The Political Methodologist about making high-resolution graphics for academic publishing is a great start.