A Short Course Book
Sensors, Pixels and Image Sizes

Exploring Pixels On The Screen

 
 
Click to open an Excel worksheet and use Part 2. Displaying Images to follow the instructions in this section.
Part 2 on the Excel worksheet "Pixels & Images Calculator" calculates the size of an image displayed on the screen. The numbers in the descriptions that follow refer to row numbers on the worksheet.

1. Width of image (in pixels) is where you enter the image's width in pixels.

2. Height of image (in pixels) is where you enter the image's height in pixels.

3. Screen's horizontal width (inches) is where you enter your screen's width in inches (not its advertised diagonal measurement).

4. Screen's horizontal resolution (pixels) is where you enter your screen's horizontal resolution. For example, if resolution is set to 800 x 600, enter 800. If it's set to 1024 x 768, enter 1024.

6. Screen's PPI (pixels per inch) is calculated by dividing the screen's horizontal resolution in pixels (line 4) by its actual width in inches (line 3). In the illustration above it divides 1024 by 16 for a ppi of 64.

7. Width of image on screen (in inches) is calculated by dividing the width of the image in pixels (line 1) by the screen's ppi (line 5). In the illustration above it divides 3000 by 64 for an image width of 46.9 inches.

8. Height of the image on screen (in inches) is calculated by dividing the height of the image in pixels (line 2) by the screen's ppi (line 5).

9. Will image fit on screen? is calculated by comparing the width of the image in pixels (line 1), with the screen's horizontal resolution in pixels (line 4). If the image is equal to or smaller than the screen (in pixels), it will fit (YES), otherwise it won't (NO).

Exercises

Open the worksheet by clicking the Excel button in this section and enter numbers in the green cells to explore the questions that follow.

1. If your image is 1600 x 1200 pixels, how wide will it be when displayed on your screen? Will it fit?

2. If your image is 1200 x 800 pixels, how large will it be when displayed on your screen? Will it fit?



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