graphics and images communicating information : documents and publications

Graphics and Images

Communicating Information : Documents and Publications

What image?

A graphic is an image … a picture.

to inform?to explain

to remind

to entertain

to shock

to instruct

to guideto simplify

to help

Why would you use a graphic or image?

to inform

to explain?

to remind

to entertain

to shock

to instruct

to guideto simplify

to help

Why would you use a graphic or image?

to inform

to explain

to remind

to entertain

to shock

to instruct?

to guideto simplify

to help

Why would you use a graphic or image?

to inform

to explain

to remind

to entertain?

to shock

to instruct

to guideto simplify

to help

Why would you use a graphic or image?

to inform

to explain

to remind

to entertain

to shock

to instruct

to guide?to simplify

to help

Why would you use a graphic or image?

to inform

to explain

to remind

to entertain

to shock

to instruct

to guideto simplify?

to help

Why would you use a graphic or image?

to inform

to explain

to remind

to entertain

to shock?

to instruct

to guideto simplify

to help

Why would you use a graphic or image?

How do you think images are captured on a computer?

You can capture images using certain devices connected to the computer.

You can also create images on the computer using different types of software or programs.

There are painting programs and drawing programs.

Can you remember any that you have used?

Dots, dots, dots

All captured images are called bitmap images.

If you take a close look you will see that an image is made up of dots. In fact they can be made up of thousands, hundreds of thousands or even millions of dots!

These dots are called pixels.

The higher the dpi, the better quality the image.

The dpi of the image is called the resolution.

An image with lots of dpi is a high resolution image.

An image with a small amount of dpi is a low resolution image.

Higher or lower

Bitmap images are measured in dots per inch, otherwise known as dpi.

Points, points, points

The other type of images are vector images. These images are created in special drawing programs.

Vector images are made up of lines and shapes. These can be grouped together to make up another shape.

When images are made bigger the quality remains the same.

Dots or points

Choosing a bitmap or vector image depends on why you are using the image.

description:

examples:

advantages:

disadvantages:

Bitmap

an image made up of tiny dots called pixels

photos captured using a scanner; an image created in a paint program

the colour of each individual dot can be changed

the quality suffers as the image is made bigger; nothing can be added behind or in front of the image; can take up a lot of computer memory.

description:

examples:

advantages:

Vector

an image made up of lines and shapes

plan of a room in a house;a company logo

does not take up much memory; lines and shapes can be grouped and placed in front or behind each other; the quality remains the same as image is made bigger.

only the colour of whole lines or shapes can be changed.

disadvantages:

Chopping and changing

An image can be manipulated (changed) in many ways.

Chopping and changing

I’m saved!

It is important to save images so they can be used at another time.

There are a number of formats that images can be saved as. On the following slides are the most widely used on PCs:

.tiff

.bmp

.gif

.jpeg

.png

At a loss?

File formats come in two types: lossy and lossless.

Lossy formats lose some of the image colours when the file is saved (those not usually seen by the naked eye!).While the quality of the image may not be the best possible, lossy formats are useful as they do not take up a lot of memory.

Lossless formats save the image as it is – this ensures that the quality remains the same. However, they take up more memory than a lossy format. 

File Quality Memory used

Benefits

.tiff lossless high Very good quality images.

Ideal for printing.

.bmp lossless high Very good quality images.

Ideal for printing.

.gif lossless low Used for images with less than 256 colours. Ideal for animations, text and line drawings, and web site animations.

Has transparency feature.

.jpeg lossy low Good images with up to 16 million colours. Not first choice for printing.

Very good for web site photographs.

.png lossless Very low Images of any quality, printed or not.

Very good for images on a web site.

Summary

There are two types of graphics, bitmap and vector.

Images can be captured or created.

The higher the resolution of an image, the better the quality.

There are many ways an image can be manipulated.

Images can be saved in many formats, including .bmp, .tiff, .png, .jpeg and .gif.

What can I remember?