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:
- Cleaning the scanner glass before starting,
and keeping it clean between scans.
- Avoiding getting fingerprints on the scanner glass or the prints to
be scanned.
- Making sure that prints are square on the glass so that
when we crop edges we retain as many useful pixels as possible.
- Scanning at the optimal or natural resolution of the scanner
(for example, 150dpi for the HP ScanJet 5100C).
- Scanning in mono if the image is mono.
- 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)):
- Inspect the scanner glass and the print for dust and dirt. Clean
gently if necessary.
- 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).
- Initiate a scan from the application:
- On NT4, with PSP5 and the HP ScanJet 5100C: in PSP
enter the hot-key-sequence Alt-FITQ, and when the scanner
dialogue box pops up select scan-in-colour or not as
appropriate to the image, and click the Scan button.
(All fancy features should be turned off and the scan should
be at 150dpi.) When the scan completes, View the Entire Scanner Bed
and select the image area for the print, leaving a little space
round all the edges. Then click the Accept button to return
to PSP. All of these steps take a while (as much as two or three
minutes), and you may get a dialogue box complaining that something
timed out or was busy, in which case you should click the Retry
button.
- 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.)
- 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.
- 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.
- 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.