DHD Photo Gallery: How To Scan Prints for the Gallery

Usually, when scanning prints for the Gallery we produce JPEG images (file extension .jpg). JPEG is designed to efficiently store photographic images.

Sometimes we create GIF images (file extension .gif). GIF is designed to store computer-generated images, but it can be very effective for storing (for example) two-colour images such as text.

Very rarely other image formats will be used.

In all cases we try to get good scans by:

  1. Cleaning the scanner glass before starting, and keeping it clean between scans.
  2. Avoiding getting fingerprints on the scanner glass or the prints to be scanned.
  3. Making sure that prints are square on the glass so that when we crop edges we retain as many useful pixels as possible.
  4. Scanning at the optimal or natural resolution of the scanner (for example, 150dpi for the HP ScanJet 5100C).
  5. Scanning in mono if the image is mono.
  6. Cropping off artifacts and edges after scanning.

Procedure For Each Scan

A similar procedure should be followed for each scan, having entered whatever software it to be used to drive the scanning process (usually PaintShop Pro (PSP)):
  1. Inspect the scanner glass and the print for dust and dirt. Clean gently if necessary.
  2. Align the print square on the glass a little way from the edges so that all of the image can be captured (the scanners usually cannot scan right to the edge of the glass).
  3. Initiate a scan from the application:
  4. Back in the main application (eg PSP), trim off the edges of the image by cropping the image. (This may include removing scanning artifacts. For example, with the HP ScanJet the bottom line of returned pixels is almost always completely black and should be removed.)
  5. Save the image in a pre-selected directory in which you intend to deliver all the finished scans. Save in JPEG (.jpg) format with a compression of 10 (or an image quality of 75% if that is how you are offered image quality settings). Use a filename name that fits the Gallery's standard naming scheme. If the image is monochrome use the attribute word ``mono'' as the last attribute word.
  6. You might wish to try to make a tweaked version of the image (by adjusting contrast and sharpness) or a distorted version or a posterised version. You may want to airbrush out minor defects. Save these adjusted images, if possible, using the same name as the main image you just did except with extra attribute words. The aim is that the original image, unprocessed except for cropping, is available in the Gallery, along with any adjusted images you subjectively feel to be better. Note that what looks better on your screen to you might not look better to other users, so it is important to leave them the original image to work on.
  7. Occasionally load an image back in and make sure that it does not look horribly distorted or low quality, since this might indicate that you have save settings wrong.

Where possible, each folder of prints will be marked with the author's initials, which you will need for the image names. The folder may also be marked with the initial descriptive words to use for most of the images, and any other special instructions. Check to see if similar images are already present in the Gallery to keep names similar to, but not clashing with, images already present. The search tool in the Gallery may help locate such existing images.

You may like to read How many pixels are there in a frame of 35mm film? where Brad Templeton suggests that a good 35mm film frame holds the rough equivalent of 20 million pixels in a digitised image, eg from a digital camera or a scan of an analogue film image.

Damon


Site content copyright Damon Hart-Davis 1996-2007 unless otherwise stated.