Essential Skill 1

Image size and ResolutionOn the Printed image and

On the screen

The Printed ImageI want you to be able to state WHY one image will print better than another.

The more pixels per inch (DPI) an image has the better it will print.

64dpi, (actual pixels)

64 dpi, 8 inches x 8 inches

150 dpi, 8 inches x 8 inches

Here’s the Math

W   H   W   H  10 x 8 image with 1440 x 1120 Pixels

Divide the Pixels by the inches to get the  DPI of the Image   1440  / 10 140 DPI        

W   H          10 x 8 image @ 300 DPI  

Multiply the inches by the DPI to get the total pixels   10 x 300 3000px  8 x 300 2400px        

Which of these images will print at a higher resolution?

Here’s the MathYour turn:Which of these images will print at a higher resolution?

W   H   W   H  6 x 4 image with 900 x 600 Pixels

Divide the Pixels by the inches to get the  DPI of the Image   900  / 6       DPI      

W   H          7 x 5 image @ 200 DPI  

Multiply the inches by the DPI to get the total pixels   7 x 200              px  5 x 200              px        

Why? The more pixels per inch (DPI) creates a better image.

64 dpi, 8 inches x 8 inches

Let’s look at the differences:• the 64 dpi image has fewer pixels per inch• These pixels are larger, we can see them they are so large.• There are fewer colors• If the image were only an inch square, the pixels would not be big.

Why? The more pixels per inch (DPI) creates a better image.

Let’s look at the differences:• the 150 dpi image has more pixels per inch• These pixels are small, we cannot see them they are so small.• There are many more color options• If the image were twice as large, the pixels would be bigger and the DPI would be smaller.

150 dpi, 8 inches x 8 inches

On the ScreenActual Pixels at 64 DPI.

The image is tiny on the screen

On the Screen

Actual Pixels at 75 DPI. @ 600px

The image fits on the screen when the number of pixels are fewer than the screen maximum.

On the Screen

Actual Pixels at 75 DPI @ 1200px.

The image doesn’t fit on the screen when the number of pixels are greater than the screen maximum.

On the Screen

Actual Pixels at 150 DPI @ 1200px.

The image STILL doesn’t fit on the screen the number of pixels are the same as the 75dpi image.

How Does DPI affect the Screen?

When the number of pixels of the image exceeds the maximum number of pixels the screen can view the image will be too large to fit on the screen when viewed as actual pixels. Does the clarity of the image change?

NO, the clarity is exactly the same. Let’s look back.

Here’s the Math

W   H   W   H  10 x 8 image with 1440 x 1120 Pixels

Divide the Pixels by the inches to get the  DPI of the Image   1440  / 10 140 DPI        

W   H          10 x 8 image @ 300 DPI  

Multiply the inches by the DPI to get the total pixels   10 x 300 3000px  8 x 300 2400px        

\Which of these images will appear larger on the computer screen?

Here’s the MathYour turn:Which of these images will appear larger on the computer screen?

W   H   W   H  6 x 4 image with 900 x 600 Pixels

Divide the Pixels by the inches to get the  DPI of the Image   900  / 6       DPI      

W   H          7 x 5 image @ 200 DPI  

Multiply the inches by the DPI to get the total pixels   7 x 200              px  5 x 200              px