When it comes to scanning, many people today have multi-function printers that will also scan photographs. When you scan in an image from a print your scanning software does it all for you, you just hit a button and the job is done.
Before you send a photograph scan for repair, you need to look at the settings in the software to see how it is going to save your image. Does it give you any options to alter the way the file is saved or scanned? Most scanning software will give you a choice between a TIFF file or a JPG file. Look at the software that came with your scanner and check if you have the option to change the way it saves your images. Phrases to look for in the manual or software settings are best setting or the lowest compression, lossless format or large file size. Look for the top setting.
A TIFF file, although larger, will give the best results. A JPEG file is a format that discards data to save space when saving. The higher the compression the more data is discarded and the less detail there will be in your image. Try to scan you image so the longest side of the photo ends up at around 3000 pixels long, just crop to scan the photo not the whole scanner bed. To do this measure your photo in inches and set the scanning DPI (dots per inch) as near as possible to these suggested settings: