How To Scan
The do’s and don’ts of basic scanning for design. I think you could easily divide scanning duties into two basic types. Type one would be a low resolution for placement only or digitizing hand work like thumbnails and roughs for class or group presentations using a computer for presentation. The second type would be high-resolution for final offset printing. Rarely do we as students at UCO need to scan for high-resolution output like offset printing. The resolution necessary for our printers in the print center is much lower than high-resolution image or plate-setters used in commercial offset printing. The industry standard for high-resolution offset printing is two times the halftone dot size used to print. About 10 years ago when most of these formulas were being set, the standard screen range for color offset printing was 150 LPI, so, 2×150=300. That’s where the magic number 300 PPI came from. As a senior in our program, you will learn more about this in Pre-press class. As I mentioned the printers we use in our print center are lower resolution printers. You could probably get by with a pixel per inch ratio of 100 but to be on the safe side I usually tell students to scan at 150. If your end result will never be printed and will only be seen on the computer you could get by with only 72 PPI because that is all the computer monitor can see.
I am going to walk you through using the Epson scanner in the Computer Lab. If you have a personal scanner at home or you use another scanner on campus or use a Windows PC the method or terminology might vary from scanner to scanner.
Step one, open the software Image Capture from the Applications folder. Click on Go in the menu bar and select the Applications folder. In the Applications folder scroll down to Image Capture and double-click to launch the software.
You have several selections to make in this dialog box. First set the Kind. For most black and white images like pencil thumbnails, roughs and B/W photos, select Black & White. This is a basic greyscale selection. If your image is pure black and white and has no gray values choose Type. This is a bitmap selection. If your image is color choose the Color selection. Next select the resolution, I recommend 150 dpi. Check the Use Custom Size box. Set Auto Selection to Detect Enclosing Box. Set the Scan To: Desktop. Name: re-name with description or your name. Format: JPEG. Image Correction: none. Unsharp Mask: Low or Medium. Descreening: Descreening is another misunderstood term. When a printed photograph (halftone) is scanned Photoshop applies another halftone dot on top of the existing dot pattern creating a pattern called a moire´. This moire´ pattern usually creates an undesirable texture. The Descreening feature allows you to scan and smooth out this texture. You do not ever need to use it on non-halftone images, so set it to none. Backlight Correction and Dust Removal are for photographs so set them to none. Click the overview button for a preview image. Adjust the selection box to fit tightly around the image and then click the Scan button. Your image will be scanned and saved to the Desktop.
Open your scanned image in Photoshop.
If your scan is a greyscale black & white image click the Auto button to automatically adjust the levels giving you a better balance in contrast and density. If your image is color select Options and click on the Find Dark & Light Colors button and check the Snap Neutral Midtones box then click OK.
That’s the basics for low resolution scanning for almost all your design needs. GOOD LUCK and HAPPY SCANNING!