Over the years
I've had numerous customers send digital image files from
film photos they have scanned and request photo
enlargement and prints. In almost every circumstance, the
files received were scanned at too low a resolution to
produce photo enlargement without resampling the original
digital file to produce the requested print size. Every
time you resample a digital file, the original image
quality will degrade, producing a lower visual quality
photo enlargement.
There is a simple technique we use when scanning film
photos for photo enlargement that will produce the exact
print resolution required for your particular digital
photo printing system. All you need is a good quality
scanner that can scan with an optical scanning resolution
of 2400 dpi or more, and has a scanning setup mode that
allows you to enter specific sizes and resolutions, with
an image output scale or percentage listed. You must also
be able to "select" the original photo with a
marquee selection tool, or a similar manner to select and
scan only the area of the photo.
When I say "Optical" scanning resolution I mean
strictly optical. All scanners will have listed scan
resolution available that are extremely high. These are
usually interpolated or digitally resampled resolutions.
You may have to check the scanners specifications to find
out what it's actual optical scanning limit is. Any
resolution used that is higher than the listed optical
resolution, will resample the digital image.
The scanning setup window or mode must allow you to enter
specific parameter sizes for the output image, and allow
you to enter specific scan resolutions or dpi. Most better
quality scanners will have a "professional" type
mode you can access to set up your scan. You will not be
able to use this photo enlargement technique with the
"quick scan" or "auto scan" type of
application.
To fine tune the output image, or to crop to an exact
print size, you should also have installed an image
editing software such as Photoshop. The scanned image will
not usually come out as an exact print size.
This photo enlargement technique will work equally well
with any type of original film photograph. If your scanner
can accept negatives or transparencies, the same process
can be used to format photo enlargements from these types
of original film photographs.
To illustrate this photo enlargement technique, we will be
scanning from Photoshop CS using an original 4x6 photo
print. To set up the scan, you need to know just two
specific items. One, the size of the photo enlargement or
output print size. Two, the resolution or dpi required for
printing the photo enlargement. We will produce a photo
enlargement of 11x14 at a printing resolution of 300 dpi.
Step One:
Place the photo on the scan bed and open the scanner setup
window. Preview the photo and select the entire photo with
the selection marquee. We will say the photo is a portrait
orientation photo, with the photo height as the long side
and vertical.
Step Two:
Enter 11 inches in the width field of the scan setup
window destination or target section. You will see a
corresponding height of 16.38 inches. If you were to enter
14 inches in the height field, the image width would only
be about 9 inches, not large enough for your target photo
enlargement. Here you may need to enter your target
dimensions in either the width or height to determine
which you need to enter to produce a large enough photo
enlargement size. You can crop the photo enlargement to
the exact print size later in Photoshop.
Step Three:
Check the scale or percentage field of the scan setup and
you will see the dimensions you entered in the target size
fields produce a 273% photo enlargement. This actually
relates to a photo enlargement of 2.73 times the original
photo size. Since you know you want to print the photo at
a resolution of 300 dpi, you need to scan the original
photo at a resolution of 300 x 2.73, or 819 dpi. Enter 819
dpi in the destination or output section resolution of the
scanner setup window.
Step Four:
Since the actual photo enlargement will be produced
through the digital image resolution, you then set the
scale or percentage back to 100% and enter the original
sizes or 4 inches width and 6 inches height back into the
destination or output sizes in the scan setup.
Step Five:
So you should have your scanner setup with the original
photo sizes of 4x6, at a scale of 100%, and a scanning
resolution of 819 dpi. Go ahead and scan the image into
Photoshop. Check your final image size in Photoshop by
Image > Image size. We ended up with an image 4.029 x
6.0 at 819 dpi. To create the photo enlargement, simply
uncheck resample in the image size window, and enter 300
in the resolution field. This will create an image
11x16.38 at 300 dpi.
Step Six:
To crop the photo enlargement to an exact 11x14, just
select the crop tool, enter in the crop parameters width
11 inches, height 14 inches, and resolution 300. Drag the
crop box over the entire image and position as you like.
Click the crop check mark in the upper right of the screen
and you have a perfectly sized 11x14 image at 300 dpi
resolution ready for printing with no image digital
resampling or re-sizing.
The whole point with this photo enlargement technique is
to first, use the scanner settings to determine the
scanning resolution dpi needed to produce the target photo
enlargement size, then scan the original photo at the
original size and 100% scale. When you scan a photo at
it's original size with the "scale" at anything
but 100%, the scanner software resamples or interpolates
the digital file. This will produce a lower visual quality
image.
More information on photo
enlargement of film photos can be found on our
Website, or if you have any questions concerning this
photo enlargement scanning technique, feel free to contact
me. |
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