Computer Graphics 101
Most computer graphics fall into one of two distinct categories: "vector"
or "bitmapped". Both of these formats excel in certain areas. Understanding
their basic differences will help you know what you can do with each of them and
is important for anyone interested in computer scrapbooking!
Bit mapped graphics are also called: "pixel based"," raster",
or "paint" graphics. The software programs used to create and edit bitmapped
graphics are generally referred to as "image editing", "photo",
or "paint" programs. Some of the more common varieties of bitmapped
images are: JPG, GIF, TIF, BMP, PCX, and PICT.
Vector graphics are sometimes referred to as "draw" graphics. The programs
used to create vector graphics are often referred to as "draw" or "illustration"
programs. There are fewer generic formats for vector graphics. The most common
ones are WMF, EPS, and PICT.
A bitmapped graphic is a pattern of tiny square dots called "pixels".
Each pixel has a color and the pattern of all of the colored pixels creates the
image we see. Bit mapped images are always a rectangular or square shape and every
pixel within graphic must have a color assigned to it. White is a color too and
if no other color is given to a pixel, it is assigned the color white. Because
of this, bitmapped images do not have transparent backgrounds. Digital photographs
are good examples of bitmapped images.
The internal structure of vector based graphics is totally different than bitmapped
graphics. Where bitmapped graphics use colored pixels to create an image, vector
based graphics are made up of a series of mathematical instructions that tell
a software program how to "draw" the image.
An example of a vector based graphic would be an instruction, in the graphic file,
that tells the computer to: "Draw a red circle that is 1 unit wide by 1 unit
tall." Vector graphics can be very complex, but this simple example illustrates
the way they are constructed. Vector graphics are also generally much more complicated
to create. Because of this, they're primarily found in commercial clip art products
or professional illustrations.
Now that we've gone over the basic structure of these two formats, lets look at
their strengths as well as why and where you should use both for scrapbooking.
Digital photographs are always bitmapped graphics. In fact, a traditional photograph
is very similar to a bitmapped graphic. If you enlarge a regular photograph up
big enough, you can see the little colored dots that create the picture, the same
as in a bitmapped computer graphic.
Other than digital photos, the best format choice for the other graphics you use
for scrapbooking will generally be vector based graphics.
Vector graphics can, and generally do, have transparent backgrounds. This is a
wonderful feature of this format and gives you the flexibility to layer graphics
on top of backgrounds, photos, other graphics, and text too. You can't do this
with bitmapped graphics because they are always a rectangle or square shape of
pixels with every pixel having a color assigned to it.
A great feature of vector based graphics is their ability to be resized as large
or small as you like. Vector images don't rely on a set number of pixels, like
in bitmapped graphics, to draw the image. Instead, they uses instructions that
tell the software program how to draw the image, and, how big to make it. So,
regardless of size, vector images always print as sharp, high resolution images.
This gives you unlimited flexibility when creating scrapbook pages because you
don't have to worry about the image becoming blurry or rough. You have complete
freedom to use the graphic at whatever size you like.
This isn't the case with bitmapped graphics. When you enlarge the size of a bitmapped
image, the pixels that make up the image get bigger too. With minor enlargements
this may not be a problem. But, if you want to take a small graphic and make it
big, the pixels will become visible, the image fuzzy, and the graphic may start
to look like it has a jagged edge. This same thing happens when you enlarge a
regular photograph too, but the problem is more evident with a computer bitmapped
image because pixels are square instead of round.
Another important difference in the way bitmapped versus vector images work has
to do with the ability to rotate images. Vector graphics are easily rotated at
any angle because there are no pixels in the image to deal with. With most layout
programs, you can rotate a vector graphic any amount you like and the image still
retains it's high resolution sharpness.
Because of the square pixels that make up a bitmapped image they are not nearly
as easy to rotate without in some way hurting the quality of the image. Rotating
an image in exact 90 degree increments is not a problem, but at any other angles,
the pixels do not align exactly the same and the image quality deteriorates.
A final difference has to do with the "resolution" of the images. Resolution
has to do with how sharp images appear and is related to the density of the pixels
in an image. Again, because vector graphics are not constructed of pixels, it's
not something you have to be concerned about. Regardless of how big, small, or
the angle you make a vector graphic, it will always print at the highest resolution
of your printer.
Bit mapped graphics are more complicated to work with because their resolution
can vary from image to image. The resolution of bitmapped graphics is something
you need to be aware of and use properly so that your scrapbook pages will look
their best. Typically you want your photographs to have a resolution of at least
200 dots per inch for printing.
A discussion about image resolution, dpi, and all the other terminology and considerations
is a whole topic by itself, and, one we won't cover here. The important point
is that this is something you need to be aware of and need to manage properly
when you are using bitmapped images.
Computer graphics and their formats is probably the most complicated aspect of
computer scrapbooking. Hopefully this overview of the two has helped give you
a better understanding of the them and their differences. Both formats have a
place on our scrapbook pages.
Digital photographs are bitmapped graphics regardless of if they come from a scanner,
photo lab, or a digital camera. Scanners only create bitmapped images, so any
scanned memorabilia you add to your pages will be in this format too. Keep this
in mind when planning your pages and you'll experiences less unpleasant surprises
or frustrations while getting your pages completed.
Other than photographs and scanned memorabilia, vector graphics are generally
much easier to use and should be your first choice whenever possible. They offer
more flexibility for sizing, layering, and rotating than bitmapped images do,
plus, they will always print as high quality images. This isn't meant to suggest
that you should never use bitmapped graphics, just that you should be selective
in the ones you do use, and, that you do need to remember their limitations.
Finally, always remember that anything you add to your scrapbook pages should
be there as an enhancement to them. Selecting the right images can add lots of
entertaining value to your designs, and, understanding how to select and best
use those graphics can make a world of difference!