Image
Format:
As you build your flyers, postcards, business
cards, etc. you'll almost always want to add photos or other images.
When creating artwork for printing, there are two formats of images
you'll work with--vector art and raster art. Each type of image has
distinct uses, advantages and limitations.
Vector Art
Vector art is a combination of various shapes such as squares, circles,
triangles, and asymmetric items that are defined by mathematical
formulas called vectors. These files have a large advantage because
their file size is small, they can be easily manipulated and may be
enlarged to any size without sacrificing quality. However, it is
extremely difficult to create photorealistic or life-like
representations in the vector format.
Vector images are usually built in programs like Adobe
Illustrator, CorelDraw and Macromedia Freehand. Additionally, most
clip-art you import into programs like Microsoft Publisher, Powerpoint
and Word are also in the vector format.
Raster Art
 Raster
images are made up of small squares or dots called pixels. Each pixel is
assigned a specific color, and the combination of these pixels creates
the illusion of a continuous image. Raster images are generally used for
photographs and other highly-realistic images, and are usually created
by scanning photos, printed images or actual items. Raster art is
usually edited in programs such as Adobe Photoshop, Corel PhotoPaint,
and Paint Shop Pro.
Raster images have the advantage of portraying
accurate characterizations of photo and life-like images. However, the
file size can be quite large, they are difficult to manipulate and you
can not enlarge them without losing image quality. |
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Image
Resolution:
Image resolution denotes the size and spacing
of pixels in a raster image. It is measured in dots per inch, or "dpi."
In other words, resolution represents the overall sharpness of your
image on the screen or paper. The higher the resolution, the more pixels
in the image and consequently the detail is sharper and you'll have
finer color transitions within an image.
The typical monitor resolution is 72 dpi. Monitor resolution
determines the display size of an image. It is important to realize that
a computer monitor is a different medium than a printed magazine or
newsletter.
All raster images and photos should be created at 300 dpi at 100%
size. If you wish, you can submit images at lower resolutions, but be
forewarned that your output may not be as sharp and crisp as you'd
like.
Remember, the file should be measured at 100% size. For example, if
you have a two inch by two inch photo, and you enlarge it to four by
four, your effective resolution will be cut in half, or 150dpi.
Conversely, you may have a 72 dpi file that is 5 by 7 and you only
require a 1 by 1.5 image in your document. In such a case, your photo
will be around 302 dpi and will print nicely. |
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300 dpi |
150 dpi |
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300 dpi |
72 dpi |
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Don't Make These Mistakes
With Raster Images:
A common mistake is to copy images directly
off a website and place them into your artwork. These images are created
at 72 dpi, and they tend to look blurry when printed. Images used for
the Internet are kept to a small file size for quicker downloading and
viewing. They are usually at a low resolution, 72 dpi since that is
typically the monitor resolution. Resolution matters. Images on the web
should not be saved to use for publishing any printed matter. They are
usually not the correct image size or resolution.
Another mistake is to take a low resolution image into a
photo-editing program and simply "res" it up. This means that you take a
photo that is 72 dpi and simply change the resolution to 300. This does
not work. Instead, you need to create, scan or take a digital photo in
the correct resolution.
Image Compression:
Affordable Image is able to accept your .jpg
(JPEG) files. JPEG is a file format in which images with continuously
varying tones benefit from compression, and is most commonly used in web
design. Since a .jpg file can have a significantly smaller file size
that .tif or .eps files, people are starting to use them in the print
industry.
The .jpg format allows you to choose your level of
compression. Some programs, like Photoshop, have an "image quality"
control when you are saving a .jpg file. Other programs give you a
compression percentage option.
When dealing with this format, the key is to balance
quality and size. Usually, your image will work fine when you set image
quality to 75% or greater (or compressed less than 12%.) Image quality
degrades significantly if you overcompress the file, especially around
sharp color transitions.
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No Compression |
Over Compressed |
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No Compression |
Over Compressed |
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The photo on the left is much clearer
than the one on the right. Notice the loss of quality around the arm. |
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Notice the distortion around the A. Loss of quality is especially
noticeable when you have color transitions. |
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| Remember that we will
accept low resolution and over compressed files. It's up to you. Just be
sure that you understand that your images may appear blurry or jagged.
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