Resample reduction & sharpening tips?

[InSite Data]

I have a digital camera that takes 3000x2000 images. It's great for prints but can be challenging to get a sharp web image after reducing multiple times. I’ve been mostly pleased with the reduced images but I don’t know if I’m using the best approach. Can anyone point me recommendations or tips on the best way to resample / sharpen down to a web images such as 576 x 384 from 3000 x 2000? I’ve seen recommendations to limit the downsizing to a third at a time. Others said 10% at a time. I want to set up an action so I can automate this. Does it work better to resample down in one shot and then sharpen? Does it work better to resample multiple times, sharpening slightly each time? I’ve been reducing 10 – 20% at a time and sharpening slightly every few times until I get to the final size. Then I sharpen as needed. What do people do most of the time?

Thanks,

Dave

[Jake Hannam]

In Site Data,

Most likely, your camera produces JPG images (which compresses files). Before you do anything, save it using a different file format such as TIF or PSD.
These are 'lossless' file formats so you won't lose anything each time you save as you do if you are using JPG. Then, do your sharpening and resampling as suggested by Tony and Mac above.

I recommend that you do all your editing, sharpening, flattening, etc. at full resolution and then resample and save for web. At this point (save for web), you will have a JPG or GIF or PNG file suitable for use on a web page. Keep the high resolution TIF file on your system or CD for future use (don't save it with the resampling or flattening because you can always go back and do that again).

[Colin Walls]

If I understand the process correctly, downsampling in stages would degrade the image, unless it were done in careful percentages, in which case it would be harmless but pointless.

Now upsampling is another matter ...

I would also say that sharpening should, if it's really necessary, be done at the end. But bear in mind that this will increase the JPEG file size.