Example: Using Thumbnail Images

Consider the following image, which is a 26k JPEG, 400x300 pixels:

Internet kiosk user in Kenya

If we wanted to produce a thumbnail image one third the size, i.e. 133x100 pixels, we could simply scale the image to this size:

Scaling the thumbnail makes the subject too small Internet kiosk user in Kenya (26k)

Unfortunately this makes the subject too small. We could also try cropping the image as follows:

Cropping the image loses the context Internet kiosk user in Kenya (26k)

But this loses the context of the original photo. The solution is first to extract the most important part of the original:

Important part of photo

and then to scale to the appropriate size:

Final thumbnail scaled and cropped Internet kiosk user in Kenya (26k)