Graphics Programs Reference
In-Depth Information
printer? You'll need to make lots of choices, but they should be
based on where the image needs to end up. Know the destination
of your image so you'll know which path to take.
The process of resampling allows you to change the pixel dimen-
sions of your image. This will affect the display and print size
of your image. This part of the resizing process is important for
several reasons:
•
Images will print faster when they are sized properly for your
output device.
•
Images will print clearer when you size them to a target size
and then run a sharpening filter to enhance the edge detail.
•
Images appear crisper when they are displayed at 100 percent
on a computer screen (such as for a PowerPoint presentation
or website).
Tip
Start Out Right:
Digital Cameras
If you're acquiring a digital image,
be sure to capture enough pixels.
If you want an 8 x 10 inch print
and need 300 dpi, do the math
before shooting. Multiply the inch
size by the print resolution. In this
example: 8 x 300 = 2400 and
10 x 300 = 3000—therefore,
2400 x 3000 = 7,200,000, which
is about 7.2 megapixels. To allow
for cropping, you'll want to shoot
at an even higher resolution.
The process of resampling is often identified based on whether
you are scaling the image smaller (downsampling) or larger
(upsampling):
•
Downsampling. If you decrease the number of pixels in an
image, you are downsampling the image, which permanently
discards data. You can specify an interpolation method (dis-
cussed in the next section) to determine how pixels are deleted.
•
Upsampling. When upsampling, you create new pixels to
expand the image. Again, you can specify an interpolation
method to determine how pixels are added. When upsampling,
you add information that did not previously exist, which gener-
ally just makes a larger image that may appear less sharp than
the original.
Choose an Interpolation Method
When you resample an image, Photoshop creates new pixels.
Those new pixels are created based on the neighboring pixels.
How those new pixels are formed is determined by the interpola-
tion method you specify. Photoshop offers up to six methods to
resample your image.
