User Guide

Academic Courseware: Chapter 1

Joyce Ryan

Create a grayscale gradient

In Corel Painter, open a new file, 640 x 100 pixels at a

resolution of 72 ppi. Fill it with a grayscale gradation from

white to black. How many shades of gray can you see? Zoom

in on the gradient and examine it closely.

The rule of sixteen

Let’s say you want to print out your storyboard for a big client

presentation. There will be several people in the room and you want it to

look good from a distance and also upon close examination. A high-

quality look is important to impress the client. You created the

storyboard at 72 ppi, and it looked fine on your monitor. When you

printed it out, it looked awful! What happened? There weren’t enough

pixels per printed dot to give you a good-looking print. You need higher

resolution for print than you do for video. How do you find out how

much higher?

You already know it is possible to display 256 levels of gray in RGB.

Now you need to know the highest screen frequency (LPI) you should be

working at, given the capabilities of your printer. To arrive at the LPI

value, divide your printer DPI by 16 and multiply by 2. Here is a simple

example. My ink-jet printer has a resolution of 1440 dpi. If I divide that

by 16, 1440 ÷ 16 = 90. The rule of thumb is that I need 2 pixels per

printed dot to get a nice-looking image from my printer. I multiply 90 x

2, and set my resolution at 180 ppi. This should give me a full range of

tones and a beautiful print on photo glossy paper from my ink-jet

printer.

There is no LPI to worry about in video. Video defaults to 72 pixels per

inch. The important thing to know is the spatial resolution—the size of

the image as measured by its width and height. The screen resolution is

going to default to 72 ppi for video and the Web, but you need to know

the spatial resolution of your final output, in order to create your

animation at the correct dimensions and aspect ratio (the ratio of width

to height).

If you have your own printer

(ink-jet, laser, etc.), you should know

the printer DPI. If you don’t, check

your printer documentation or the

printer properties, or check with the

manufacturer. If you are using a

service bureau, they should tell you

what LPI to work at—ask! If they

don’t know, use a different service

bureau!