One aspect of digital images I haven't discussed is file size, which also includes stuff like compaction and resolution, when sending and displaying files on the internet. I haven't discussed it because the more I investigated the more complex it seemed to become. Curiouser & Curiouser to quote a certain Alice.
The basics are really simple, for the net keep it small. Hit the printer with everything you've got, Max res!
But how small is small?
Most computer monitors at the moment only display 800 by 600 pixels. Which is curious because most monitors sold have much higher resolution now. The possible explanation is that microsoft XP, and Windows 95 & 2000 all install with the 800 by 600 resolution as the default. So go check your control panel/display/settings and you may be able to slide the little screen resolution slide to the right and give yourself a screen upgrade for free. But back to the point, on the interent large photos take time to transfer. Both as an email attachment or as they are downloaded from a web page. If you are sending more than 800 by 600 the detail is probably going to waste and annoying the receiver because of the wait! If they are using a dial up connection the wait will be very painful.
What I've found is that 640 by 480 is fine for email attachments. At that size they are fast and still detailed enough. If you really must you can take them to 800 by 600, but check that the recipient has a broadband and wants to see the photos anyway.
Ok what about images on websites, web albums and photo sharing sites. Well the 800 by 600 limit is good also. But you might consider setting up some small thumbnails at say 240 by 320 (or smaller) and link the thumbnail to the larger and higher resolution version. That is how I do the images in this blog. It means the page will be delivered quicker but the user will have to click on the image they like, to then see the larger image. Hopefully they will be happy with the slight wait.