P4C: Resizing Photos for Upload

Just as we used to select different print sizes from the photo lab, we need to produce image files of different sizes for different uses in the digital age. Prints require higher resolution than displaying on screen. For example, a normal quality 4" x 6" print is 300ppi (pixels per inch), or 1,200px x 1,800px (px=pixels). That same image for use on a local screen would typically be about 682px x 1,024px, just a little smaller. On the web however, we're generally looking at images smaller than 533px x 800px. Sending that print file would typically work, but generally wastes resources and can create a poor quality image when rendered as it is resized by that website or browser. In the case of images sent to Groundspeak's servers (including Geocaching.com), the images should be no more than 600 pixels on either side. So a standard photo would be either 400px x 600px (traditional 3:2 still images) or 450px x 600px (for 4:3 video images) to upload. This will keep their servers from messing with the pixels and gives you the same image quality as you sent to them. For most other websites I stick with the 800 pixel longest edge limit as it give a good quality image without providing enough detail to be good for print (should someone steal an image without permission). For all sites you'll want to use the JPEG (.jpg) file format with higher quality, lower compression. Once you have that 600px JPEG you're ready to upload, and we'll go into that next week.

Text and images in this post are copyright 2010 by Darryl Wattenberg, all rights reserved.