scan photo prints to iPhoto

My first question is, which 'Resolution' setting should I choose ?

Depends entirely what you're going to be doing with the Photos. Jpeg is a lossy format, so as you edit each time you save some data is lost. If they require intensive editing, then the more data the better. Are you going to print them? Depending on your devices and the quality you hope to achieve, then perhaps the old 300 dpi for printing is a reasonable rule-of-thumb. If you're uploading them to the internet, say flickr or whatever, then 100 is fine. So, it depends on your proposed usage.

The scanned size at 200 ppi for one print is 2.74MB. When sent to iPhoto its size is reduced to 1MB

iPhoto doesn't reduce the size of anything on import. Where are you seeing these sizes mentioned?

Another apparent anomaly is that although the prints are all 6 inches x 4 inches, their 'info' in iPhoto can vary from anything between 1184 x 791 to 2292 x 1498, and in size from 322 KB to 985 KB.

No anomaly here. Your computer has no "inches" everything is measured in pixels. So the fact that an image is 6x4 in the real world is of no relevance. What matters is the pixel dimensions you choose to digitise (or scan) it. You can create a scan of you 6 x 4 that will be 600 x 400 pixels. (@100dpi) Or you can as easily create one the will be 14,400 x 9,600 (@2,400 dpi)... In other words, don't expect a direct correlation between what you hold in your hand and what you make on the screen. They're different worlds...

But again, iPhoto doesn't change anything on import, so I'd be looking at the scanner for explanations of these variations.

As to the file size, remember not all pixels are the same. An image that is pure white or pure black will have a smaller file size than one of a richly coloured sunset, and will also depend onn the resolution you scan at - so again, no direct correlation, it's a complex equation.

One more thing to consider is the quality of the prints you want to scan. What is the resolution of the prints? If they are old prints and grainy, there will not be much sense in scanning them with many pixels per inch. Make a few test scans with different settings and zoom in on the scanned photos. Do higher ppi settings reveal more detail in the photos, or are you just enlarging the grain or noise?

300dpi seems a reasonaable compromise between file size and your uses.

Yes, negatives can be scanned, but you'll need to read the manual of your scanner for more on that.

With regards to the size of the print scanned, initially it appears in the HP Scan window where the 'Info' button reveals the following : 'Estimated File Size (uncompressed) 2.74MB'.

In iPhoto the 'Info' button reveals the same print as 1.0MB. Is it being compressed ?

This is a mite complex. Jpeg is a compression format, not a photo format. In other words, what happens with an image is that it's wrapped in a jpeg to save disk space. (Think of it like a zip format designed specifically for photos).

So, when you view a Jpeg it's decompressed - that's what the HP Scan winodw is telling you - the size of the image in the decompressed state.

iPhoto is telling you the size of the same file in the compressed state.

The file sizes on those images will vary depending on the data within the photos - as I said above, not all pixels are equal...

Sorry I didn't respond sooner : just realised I overlooked your response, but hopefully better late than never.

You're welcome! 🙂 I'm glad you could solve the issue and I hope your scans turned out great!