One of the most frequently used and commonly misunderstood
terms in digital photography and professional printing is
"Resolution".
What is resolution?
A digital image is made up tiny dots called pixels. The
term "Resolution", when used to describe a digital
camera refers to the size of the digital image the camera
produces and is usually expressed in terms of "megapixels"
or how many million pixels it can record in a single image.
The number of pixels a camera captures is called the camera's
resolution.
A camera that captures 4,000 x 3,000 pixels produces an
image with a resolution of 12 million pixels and would be
referred to as a 12 megapixel camera. You get to 12 million
pixels by multiplying the horizontal (4,000) and vertical
(3,000) dimensions.
Why is it confusing?
In some contexts, resolution refers to the pixel count
of an image. An image with lots of pixels is often called
a "high resolution" image. But in other contexts,
resolution refers to the density of pixels in a given linear
area such as an inch. This "density" is expressed
as ppi (pixels per inch) or dpi (dots per inch) and this
density number is embedded invisibly in a digital image,
as an instruction to output devices (ex. printers). The
first type of resolution is considered "pixel count
resolution" and the second is referred to as "embedded
resolution".
What's the difference?
Embedded resolution tells your printer how far apart to
spread the pixels in a printed image. It is completely independent
of the pixel count of the image. A high-pixel-count image
can have a low embedded resolution or vice versa. Embedded
resolution is inversely proportional to the size of the
printed image. Given the same pixel count, a high embedded
resolution will result in a smaller printed image (the pixels
are packed together more tightly), and a low embedded resolution
will result in a larger image (the pixels are more spread
out).
Embedded resolution, however, does not affect the size
(in bytes) of your image or its appearance on a computer
screen. Those properties are are determined solely by the
pixel count. The byte-size of the image file is directly
proportional to the pixel count, as is its size on your
computer screen, which simply displays all the pixels in
the image in a fixed one-to-one grid.
What's the difference between ppi and dpi?
The term ppi (pixels per inch) originated in the world
of computers, and dpi (dots per inch) in the world or printing,
but today they are often used interchangeably.
Why does my image look different on my monitor
from when I print it?
One of the hardest things to understand about printing
is that the size of the image on your screen does not accurately
reflect the size of your image when you print it. An image
that fills your entire screen might only be a small thumbnail
when printed. When your image's embedded resolution is higher
than the monitor's display resolution, the image appears
larger on the screen than when printed.
Resolution Math
To understand digital image size you simply have to understand
that pixels are more tightly packed for printing than for
display on a computer screen.
Computer monitors display images at 72 ppi, meaning that
there are 72 pixels for every 1 inch of linear screen space
you see on your screen. If you have an image on the screen
that is 720 pixels wide, it will take up 10 inches of linear
screen space (72 dpi x 10 inches = 720 pixels). This may
look beautiful on the screen, but if you try to print this
image on a printer at 72 dpi the result will look extremely
choppy and jagged. To get a good looking print from your
printer you'll need to print at 300 dpi, which means that
the 10 inches across the screen will be reduced to only
2.4 inches on paper (720 / 300 = 2.4, or 24% of the original
10 inches). The result is a smaller, but much cleaner, image
on paper.
If you have any questions about resolution or want to find
out how you can get a free product shot
and a no obligation product photography quote, send us an
e-mail or call us Toll
Free at (866) 683-0306 today!
