1. Should I Buy a Scanner?

There are two types of scanners: home-use and professional-use. Home-use scanners are generally around $200 and are intended for low resolution, low quality scanning of images. Professional scanners can cost anywhere from $700-10,000+ and have the resolution, color recognition and features to produce digital images intended for professional reproduction.

Home-use scanners are good for creating digital images of pictures you wish to distribute to friends and relatives. Images created on a home-use scanner can also be used in web pages you are creating.

If you intend to scan images for printing, you will need to purchase a professional level scanner. If you do not wish to make the investment of time and money required to produce quality images, you can always rely on your print service provider. You might want to use a lower-end scanner to produce "for placement only" images in documents you create.

2. What Kind of Scanner do I Need?

If you wish to make images "for placement only," a low-end scanner will suffice. They are all similar, and have few advantages over one another. Today, a good quality scanner for printing purposes can be purchased for under $1000. For basic functionality, you need a scanner with a minimum resolution of 600x1200 dpi, 36-bit color, 3.4 density range, 8.5x11 and a transparency adapter.

Resolution: 600x1200 dpi is enough for all but the biggest enlargements. Just because you will output to a device that prints at 2400dpi doesn't mean you need a 2400 dpi image.

Bit depth: The amount of color the scanner can see, and 36 is the most common for general usage.

Density range: The ability of the scanner to see differences in light and dark areas, with the maximum light being 0.00 and maximum dark being 4.0.

Scan area: 8.5"x11" is enough for most applications.

Transparency adapter: Allows you to scan negative and positive film, including transparencies and slides.

3. What Resolution Should I Use?

The initial resolution of the scan is very important. You should always scan the image at the desired resolution, rather than using an interpolation (software) method to increase the resolution.

First, determine the desired resolution. If you are going to press, you should consider 2 x lpi (line screen), which is usually 150 for a resolution of 300dpi. If you are going to use the document in a CD ROM, Internet, email distribution or direct RIP, 100dpi should be sufficient.

Second, determine the scale factor, and use the following formula to determine the scan-in resolution.

Final Size (one side)

Current Size (same side) X Final desired resolution = Scan-in resolution

OR

Scale Factor X Final desired resolution = Scan-in resolution

The resolution matters! If the resolution is too low, your images will look bitmapped, like the image below. If the resolution is too high ,you have an unnecessarily large file, which will take up storage space, slow down your system and take a long time to output. An overly large file may even crash a printer while processing the file.

4. How do I Touch-Up the Image?

There are several things you need to do when you import images from scanners. Though there are several software packages that allow you to do image manipulation, Adobe Photoshop(r) is the industry standard, and will be discussed here. The other image adjustment software packages have similar capabilities.

Once you bring an image into Photoshop, adjust the levels. Move the outside triangles in towards the center until they touch the bulk of the data (represented by heavy lines). Then, you can do an Adjust Curves command, which allows you to change the color values of the image. With Adjust Curves, you can remove or add certain colors with the line graph, from the highlights to the shadows. Finally, if you need to sharpen the image, use the Unsharp Mask command. First, set the Radius by using the formula: (resolution in dpi /200 for regular printing; Viewing Distance (inches) x Resolution (dpi) x .0004 for posters) and the Threshold to 3. Then, move the sharpen cursor until you see the sharpness you want.

When adjusting images, you have to remember that what you see on your monitor isn't necessarily what will print out. The colors, hues and contrast can be completely different on your screen, as a monitor is an RGB device, compared to a color laser printer or printing press which are CMYK devices. Advanced Photoshop users can use the Info Palette function to look at the actual color percentages in parts of the image.

Photoshop and other image adjustment software can be complicated, but these few tips will get you going in the right direction.