In this article on Photo Shop Tips, you'll learn about the differences between resolution and measurement. Entering into the field of computer graphics is a wondrous experience, as the field is filled with endless opportunities for image creation and photo manipulation. But in the early stages, understanding the different terms can be confusing. This Photo Shop tips article will give you insight into the basics of computer graphics with a variety of tips and fundamental instructions. Learning what to do before you get started can save you many hours of frustration later on.
The Differences between Bitmapped and Vector Graphics
One of the first things you will encounter in the world of graphics are the differences between bitmaps and vector graphics. Bitmaps (also known as raster images) are defined as pixels in a grid. Each pixel contains tiny dots of color which, when combined, make up the pictures you see on-screen. Vector graphics are composed of numerous scalable objects, such as lines and curves. These are defined mathematically, so no matter how much they are scaled, a high-quality result is assured.The Relationship between Resolution and Measurements
In this section of Photo Shop Tips , we look at bitmaps. In many image manipulation programs (such as Photo Shop), you will only work with bitmaps. One issue for many new users is the relationship between resolution and the measured size of the image. One other wrinkle are the terms dots per inch (dpi) and pixels per inch (ppi). If you think of those two terms as meaning the same thing, that will reduce the confusion.
As an example, this screen shot in photo shop displays two images, a 3.75
x 5 inch photo of balloons, and a 10 x 10 inch photo of a sand dune. Yet,
balloons photo is nearly 4 times larger than the sand dune image. Why? Because
of the image resolution. The image of balloons has a resolution of 300 ppi
(pixels per inch), while the sand dune photo has a resolution of 75 ppi.
To elaborate, if you convert the image measurements to pixels only, and multiply the resolution by the dimensions, you will soon realize that the balloons photo is actually 1200 x 1500 pixels in size. In contrast, the sand dune image is 600 x 750 pixels in size.
If you were to take the 8 x 10 photo and place it within the 4 x 5
image, this is what how it would appear.
When you begin to work with images in Photo Shop, they will most likely come from a variety of sources and measurements such as inches, picas, dots, millimeters, etc. However, they all have one thing in common. They are made up of pixels. If you use image manipulation software (such as Photo Shop or Paint Shop Pro) and converting all measurements to pixels, you create a common denominator and the actual sizes of images will become apparent as you use them in your compositions.
Resolution Requirements for Different Media
Before beginning a graphics project in Photo Shop, it's important to know which resolutions are necessary. As a quick reference, Web images use a resolution of 72dpi. Newspapers use resolutions from 125dpi to 170dpi. High-quality brochures and magazines use resolutions from 200dpi to 400dpi. And for books, the range is generally from 175dpi to 350dpi.Scanning Secrets
Once you have determined the resolution(s) that you need for your graphics, the next step involves transferring the images to Photo Shop. With the exception of clip art or images on CDs, it will be necessary to either create artwork, use photographic or video capture software, or scan images into Photo Shop.Define the Purpose of the Scan
Determine the final result before you scan to make sure your images will be of the correct quality for output, whether for presentations, print, or the Web.
Start With a High-Quality Original
Before working with Photo Shop, before you begin the scanning process, it's important to make sure that the original print, negative, or transparency (slide) is of good quality. While image manipulation programs (like Photo Shop) can correct for flaws in the original (for example, its tone, brightness, etc.), you cannot bring out elements that don't exist in the original image. Also, a high-quality original means less work for you later.
Cropping During the Scan
Many scanner programs (which function in Photo Shop) allow you to crop the image during the scan. This lets you eliminate portions of the image that you don't want, and it will save you scanning time and hard drive space. Then, if additional cropping is needed, you can accomplish that with a photo editing program such as Photo Shop or page layout programs, such as such as QuarkXPress, Adobe InDesign and Pagemaker.
Scan at the Right Size
Scan the image
at the right size for your application. While you can scale images up or
down, it is important not to exceed 20% in either direction, or quality
may suffer.
More Photoshop: 
