The answer will vary depending upon what your needs are. I have spoken with many professional archivists who are scanning rare documents. Almost universally, the answer I have received is they scan documents in color at 400 dpi and save the images as .tiff. Based on their response, I have scanned about 90% of my images at 400 dpi and saved them (as they did) in .tiff format. The images are large (many exceeding 10 megabytes) and that’s ok. This is my family history; I am scanning not only for my personal interests but also for the generations that will follow. Now when I share the images, I may save duplicate images as .jpg (usually less than 1 meg in size), but the original .tiff is intact providing the key source of information. Continue reading