Pre-sized Images
When you have an image that should not expand when clicked in the html article (e.g., a head shot), you must adjust the pixel size. Generally, this only applies to news articles and editorials. For online display, it's the pixel size that counts. So a headshot that is 12 x 12 picas and 1,100 pixels looks good in the PDF but is huge online.
Resample headshots to downsize the pixels but maintain the proper size for PDFs.
120 pixels is a good size for headshots that must be placed within a text box.
220 pixels is a good size for other headshots.
First, size the image for print.
Once that has been established, you will most likely have to resample the image. Aim for 200 dpi or higher, but do not go lower than 150 dpi!
Keep in mind the orientation of the image:
if it is wider than tall, then it can be up to 520 pixels wide and look ok online. (if its a single headshot and a tight crop on the face, then keep it closer to 220 pixels).
if its taller than wide, then keep the height 425 pixels or less, preferably lower than 400.
On the first try, adjust the resolution and have the Resample set to Automatic. This will usually by fine:
If the image looks a little too blurry or off, then Undo Image Size (Ctrl-Z) and try again, but this time change the option after Resample to "Bicubic Sharper (reduction)". ( Sometimes this will make a difference, sometime it won't)
To get a good idea of how large the image will appear online, when you are in PhotoShop, view it at 100%. (Alternately, if its saved as a jpeg you can drop it on a browser window and it will show you how large it will be).