A bitmapped graphic is a photo-realistic picture made up of a grid of dots called pixels. At the lowest level, within the computer, a pixel can be stored in 1 bit of the computer’s memory. A black pixel is stored as a 1 and a white pixel as a 0.

Resolution

The resolution refers to the spacing of pixels in a picture and is measured in dots per inch (dpi). If an image has a resolution of 72 dpi, this means that it contains 5184 pixels in a square inch. (72 pixels wide x 72 pixels high = 5184).

The table below shows the difference in memory used for a black and white A4 page at different resolutions.

The diagram below shows a picture at two different resolutions. Notice the difference in picture clarity.

Increasing the resolution will give a clearer picture, but increases the memory needed to map the graphic.

Answer the following questions in your jotter.

1. Below is given a list of still graphic images that have to be created. Write down whether you would use a bitmapped or vector drawn package to create each.

a) A builder’s plan for a new house that is to be built.

b) A picture of a bunch of flowers.

c) A picture of your pet dog.

d) A chessboard.

2. How much memory is required to store the following images?

a) A black and white, 200 x 200 pixel image

b) A 2 inch by 3 inch, black and white, 300 dpi image