UNITS OF MEASUREMENT2.01 Understand Digital Raster Graphics

What Unit of Measurement to UseQuiz Question: List as many units of

measurement that you can think of as a class.

Did you have more than one from the list below?

We generally pick what we are comfortable with, but in Graphic Design it should be based on need.

Inches

The standard unit of measurement for the United States and U.S. standard sized papers.

What is 8.5” x 11” called? 11” x 14”? 11” x 17”? Letter, Legal, and Tabloid

Letter size is standard for most printers, resumes, and other common documents.

Works well when defining document sizes for print.

What most of us are comfortable with.

Pixels

The most common unit of measurement for computer screen display.

Generally represented by one dot that is illuminated on a computer screen. Many pixels make up an image or images.

A precise measurement system for web-design.

Lacks flexibility as screen sizes change.

Points

The standard unit of measurement for typefaces. 1 point represents 1/72 of an inch. Therefore text formatted with a font size of 72 pt

is about one inch. However, variations occur due to font designs.

Standard size for print paragraphs = 12 pt (Generally)

Picas Quiz time: What is 11 inches divided by 3? Quiz time, part two: What is 72 divided by 3?

One pica equals 1/6 of an inch. Six picas per inch. Often used in print design, since it is easily

divisible. Picas work well when applying the Rule of Thirds.

IMAGE RESOLUTIONAND COLOR MODE

Begin with the End

When talking about image resolution and color mode to choose when designing, you have to think about what the desired output will be.

Web? Or Print?

What is resolution? Resolution is a measure of the amount of

detail that is stored in a digital image.

Higher resolution means higher quality. But is high resolution always a good thing.

Lower resolution means lower quality. But is lower resolution always a bad thing.

Resolution is measured in PPI, or pixels per inch (the number of pixels contained in one inch). The higher the PPI, the better the

quality. The higher the PPI, the larger the file

size. Image editing software can be used

to change the resolution of an image.

Image Resolution

Images can be viewed in two ways On a screen or monitor or by printing it on paper

Monitors Monitors are low resolution devices, most display 72 ppi. Additional image resolution will increase file size, without

affecting display quality.

Printers The resolution at which printers can print is measured in

Dots Per Inch (DPI). Printers are high resolution devices and require high

resolution images in order to print images clearly without pixelation or blurriness.

Image Output Methods

Images that will be displayed on a monitor do not need a high resolution. Using a low resolution means smaller file sizes. Images with small file sizes load quicker.

Images that will be printed need a higher resolution. Images with 300 PPI are better for printing on more

sophisticated printers and will produce higher-quality photographs.

Match The Image Quality To The Delivery Method

Color Modes: a mathematical model that describes the way colors can be represented as numbers or percentages, typically with three or four values.

There are many types of color modes, but generally you will work with two when editing raster images.

RGB Color CMYK Color

What About Color Mode?

RGB: assigns an intensity value to each pixel ranging from 0 to 255 for each of the red, green, and blue components in an image.

If all RGB values are 0, you get black. If all RGB values are 255, you get white. On-screen display is represented by RGB,

therefore RGB color is best used for images that will be displayed on a monitor or webpage.

RGB Color

CMYK: assigns a percentage value for each of the process inks. Cyan, magenta, yellow, and black.

If all percentages are set to 0, the result is white. If all percentages are set to 100, the result is black.

An image should be converted to CMYK before exporting for images that will be sent to print.

CMYK Color

An image is being designed that will be display on the new company website. What color mode and what resolution should the image have?

RGB color and 72 ppi. A poster is being created that will have

500 copies printed to promote the upcoming concert. What color mode and resolution?

CMYK color and 300 ppi.

Quiz Time