What's the best way to resize an image?

Well, looking at both sets I'm not sure what you mean. The (cough) sets you linked to don't look sharper than yours. They do, however, have a much shallower depth of field (area that is in focus) and so they have a certain "pop". Shallow DOF is difficult to achieve using a p&s digicam. So I don't think sharpness is the issue here.

I use the "bicubic sharper" method to downsize images in PS, and I'm happy with it. I've never had a problem with a 500 px image seeming soft; my problem is almost always the opposite (an image seeming sharp at 500 px, but not at full size). But sharpness is not a strictly quantitative thing, so I guess it could be subjective. I downsize 3000x2000 px images to 400x266 px images with, if any change at all in the sharpness, an apparent increase, using nothing other than Photoshop CS2's "bicubic sharper" option to change the image size.

I downsize 3000x2000 px images to 400x266 px images with, if any change at all in the sharpness, an apparent increase, using nothing other than Photoshop CS2's "bicubic sharper" option to change the image size. I'm stuck with v7 for now, which boasts no such feature, unfortunately. (And thanks for the tip, rafter, will definitely try that as well.)

By and large, your daylight samples look pretty sharp to me. The low-light shot (juniors.jpg) was probably a somewhat long exposure, or shot at a high ISO, which in turn triggered a too-aggressive noise removal algorithm (a common complaint with Canons). house.jpg looks like bad digital zoom (turn it off in settings and live with what the camera can do optically). In Photoshop Image >> Image Size..., make sure you're using the "bicubic" resample option. A more fiddly tip would be to resize only to power-of-two fractions (1/2, 1/4, 1/8, etc.) of the raw size. There might be marginally less rounding error/aliasing that way. Remember that the clarity and dot pitch of your monitor also influence apparent sharpness. And last, yes, a nice prime (non-zoom) lens on a 35mm camera is always going to look a little better than the fixed zoom on a consumer digicam.

Something I've found that helps when resizing large images is to do it in multiple resizes. Going from 3000px to 500px can cause some jagged edges, something I noticed in your arch photo. But resizing in stages (from 3000 to 2000, to 1000, to 500 for example) lessens that effect, after which you can sharpen.

When resizing an image in Photoshop I use Canvas Size to keep the pixel dimensions even on both sides. Adding or subtracting a pixel this way avoids the rounding error/aliasing problems eshepard mentioned.

I sharpen twice. Once before I resize, then again after the resizing is complete. So for a digital painting that's about 5000 pixels on one side, I'll unsharp mask at .6 to 1, resize to web size (800 or 900 pixels on its' longest side), then unsharp mask at .4 or so. Of course, most digi cams that I've used leave a huge amount of deeply ugly noise in the blue channel, which wreaks havoc with my digital painting sharpening method. So before I sharpen a digital photo, I switch to LAB mode and fix the noise issue there by blurring the A and B channels a bit.

What everyone said. Another thought: I think there's a human factors aspect to it, as well. How are you assesing sharpness? It's something we can all get over stressed about. I've found myself peering at pictures up close (too close) to the screen while fussing with USM controls, trying to squeeze that very last possible iota of sharpness from an image for web presentation. Then realizing that at such a close viewing distance from a CRT no photo is going to appear perfectly sharp. Leaning back in my chair to a sensible viewing distance... "Hey, actually, that doesn't look half bad!"

I've never noticed anything but an increase of sharpness when sizing down. Are the full size images sharp? That makes the biggest difference.