Every year
digital cameras are becoming better and better at
producing higher quality photographs. This is evident by
the fact that just recently, Nikon announced it will be
phasing out film cameras from it's product line. With the
ever increasing digital resolution of today's digital
cameras, true film quality photo prints are a reality.
Whether you are printing smaller size digital photo
prints, or want to produce the largest photo enlargement
possible from your digital camera, the digital resolution
in pixels, or the camera's megapixel rating is the main
element relative to printing quality.
Digital cameras usually have the feature of setting lower
pixel resolution captures to save space on the camera's
storage card. If you ever think you will print the photos
you are taking, you should always take your digital
photographs on the camera's highest quality setting. This
setting will provide the largest amount of image data in
the photo. The photo's color, contrast and image dynamics
will always be much higher in quality, even when printed
at smaller sizes.
If you think there is the possibility of photo enlargement
of your pictures, it is highly recommended you always have
your camera set on the highest quality possible. Photo
enlargement options for digital photographs are directly
related to the density of image pixels. The higher the
original image pixel density, the larger the image can be
printed and still maintain original image quality.
Original image quality means the actual photo pixels have
not been altered in visual appearance at all.
The physical print size of any digital photo is determined
by the resolution DPI (dots per inch) assigned to the
photo file relative to the original files pixel
dimensions. With pre-print image files, the resolution is
actually stated in PPI, or pixels per inch. The higher PPI
you assign to an image file, the smaller the print size
will be.
An example of setting PPI for a digital photos:
The example is a Canon 6.3mp digital photo/highest
resolution setting.
Image dimension settings performed in Adobe Photoshop CS:
image > image size - with resample box unchecked.
Resampling the image (resample box checked) will alter
original image quality.
Original pixel dimensions: 2048x3072
Assigned PPI of 72 - image
print size = 28.444 x 42.667
Assigned PPI of 90 - image
print size = 22.756 x 34.133
Assigned PPI of 120 - image print
size = 17.067 x 25.600
Assigned PPI of 150 - image print
size = 13.653 x 20.48
Assigned PPI of 200 - image print
size = 10.24 x 15.36
Assigned PPI of 300 - image print
size = 6.827 x 10.24
As you can see by the example above, photo enlargement of
any digital photo can be accomplished simply by reducing
the assigned PPI of the image. This will work only to a
certain extent for most printing applications. As the
image input resolution (PPI) decreases, the image will
become decompressed when printed. The result will be very
low quality prints that are pixelated or very grainy or
blurred.
A general rule of thumb for image input PPI is 300 for
quality photo prints. This would apply to most standard
print systems that do not employ advanced raster image
processing software. Using the bicubic resampling feature
in Photoshop can create an image input file of about any
size you want, but resampling the original file will
always degrade image quality. The greater the degree of
resampling, the greater the degree of image degradation.
Degraded digital photos will appear pixelated, or have a
very sharp and edgy appearance.
Advanced photo enlargement techniques for digital photos
are much more complicated. These techniques utilize proper
PPI settings, advanced fractal technology software and
sophisticated raster image processing software. Proper
file management and the use of these highly advanced
software packages, can create image input files with no
adverse resampling effects. Photo enlargements with
absolute original image quality are possible. |
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