If you photograph in a few different formats, choosing a width & height for web resizing can be pretty arbitrary. For whileseated.org, I settled awhile ago on a width/height of 750/500 pixels for 35mm. Yeah, it’s bigger than it needs to be, but detail’s fun, too.
So what does one do about squares or 6x7s? After mucking around, I realized I wanted each format to have the exact same “square footage” rather than bias a particular format. I don’t know what the formula is, but here are the results for achieving an image (in three formats) that’s 375,000 sq. pixels.
Update #1: Andrew Moller writes-in from the UK with the formula!
Excellent! Thanks, Andrew! Click it for full-size.
Update #2: Chap Lovejoy sent in a resizing script (bicubic) for Photoshop based on the above formula which works great. It’s preset for an area of 375,000 pixels, but it’s editable, if you want to open it in a text editor and change it. To install, drop the script into C:\Program Files\Adobe\Photoshop (CS or CS2)\Presets\Scripts\ on a PC, or Applications> Photoshop (CS or CS2)> Presets> Scripts, on a Mac. Thanks, Chad!
Way to go, Interweb!