Getting a good scan

[Cynthia Daniel]

Here's my forumla for a good scan for the web:

1. Scan an 8x10 photo at 300 dpi. Smaller photos at a higher dpi. You want your scanner software to show a file size of around 30mb, give or take a few mb. Adjust your dpi to achieve a file of about this size. Glossy photos render a slightly better scan than matte.

2. Resize (some programs call it resampling) to the final size you want. For a web page, I use 400 pixels high so the image fits vertically within the browser screen area without vertical scrolling being necessary. The exception to this is horizontal portraits where I usually use 320 pixels high. These are not hard and fast rules, but a good rule of thumb.

3. Run unsharp mask on the image (better than sharpen), but be sure to not do so much that the image starts to "break apart" (look pixelated). Usually an image with a small face can't take as much as one with a larger face in the image.

4. Save the file and while doing this, select the file type and level of compression for .jpg files. (You'll have to select the file type of .jpg first to get this option.) For .jpg files select high quality, which will be a larger image. This is where many people go wrong by selecting a .jpg level of compression that produces an unclear, wavy or pixelated image. More and more web viewers have higher speed connections, so this is not as much of a concern as in previous days.

If you're scanning for printing:

The above dpi or higher still applies, but save the file as a tif. If you get a professonal scan in a print shop, they will likely scan at least at 600dpi, but that's more than most home computers can handle.

Be aware that tif format does not throw out any pixels and therefore is a huge file. If you're cramped for hard drive space, you can always burn these off onto a CD for later use.

If there's ever any chance you would want to do print reproduction of a painting, you might save your file as a tif and keep that as a master and create any other files, such as jpg from that one.

For the web, a good quality .jpg is what you want though, both for size considerations, plus .tif files do not display in web pages, so that's not a choice.