By Chris Dillon. Version 5, 7 September, 2009. Latest version at: www.quickanddirty.org.uk

1.    Why do we need to edit images?

• The file size of the image may be too large to go in PowerPoint or on the Web.*
• The image may be too large (i.e. too many pixels across).*
• It may be in an awkward format (i.e. not in JPEG or GIF format).
• You may only want to display part of (i.e. crop) the image.

*This is often the case if you have scanned the image or acquired it from a digital camera.

2.    Resizing an image

Open IrfanView (Start | Programs | Software E-L | IrfanView | IrfanView on WTS).

Go to File | Open and navigate to where your image is saved.

Go to Image | Resize/Resample (or press Ctrl-R) and type the desired new width or height in the Width or Height box. You should type one or the other, but not both, to avoid distortion. If the new size is larger than the original, the quality of the image may be affected. Always use pixels as the unit. To give you an idea of what 1024 x 768 pixels looks like, that is the common screen resolution these days, and so is equivalent to the size of a typical screen.

Go to File | Save as and save the image with a different name. (Always keep a copy of the original!) If the image is to go on the Internet, give it an intuitive name using only lowercase letters, numbers and hyphen. You may like to indicated its size e.g. image200w.jpg.

3.    Making the file size smaller

Resizing the image downwards (see last section) also makes the file size smaller.

This is probably not worth doing with most JPEGs, unless they are thousands of pixels across.

Open an image.

Go to File | Save as and select JPG (unless it’s an animation or the image has a transparent background, in which case select GIF). Save quality should be 100%.

4.    Cropping an image

Open the image.

Click and drag a box around the area of the image you wish to keep. If you get the box wrong, you can adjust its sides by dragging them. Go to Edit | Crop selection (or press Ctrl-Y).

5.    Converting an image to another format (e.g. .bmp to .jpg)

Go to File | Save As | Save as type and select the format and folder where you want to save the file. Click Save.

6.    Adding a border

Borders make images stand out and look professional.

Open the image.

Go to Image | Canvas size.

This allows you to add a border e.g. 2px wide to any (or probably all) of the four sides of your image and to select a colour for the border.

7.    Adding a label / Making a banner

It’s useful to be able to label an image.

You can use Image | Canvas size, if necessary, to create an area at the side(s) of your image for labels or banners (in the latter case it needs to be several hundred pixels across).

Click and drag to create a box. Go to Edit | Insert text into selection (or press Ctrl-T).

Here you can input the text. Click Choose Font to select the font, font size and colour.

8.    Rotating an image

Use Image | Rotate Left (or Right) to rotate an image 90^o. (You would need to do this if, for example, you had put your digital camera on one side to take a shot.)

You can also use Image | Custom/Fine Rotation to adjust  images that are not quite straight. 1^o one way or the other may make a big difference.

9.    Bringing pictures into Word, PowerPoint, Dreamweaver etc.

In Word and PowerPoint, use Insert | Picture | From File. The picture is then copied into your Word or PowerPoint file and becomes part of it.

In Dreamweaver, copy the image to one of the folders of your local site. You could have a dedicated folder for images, or copy the image into the folder where the page that will have your image is stored. N.B. There should be no spaces in the files names of images (or HTML pages) on the Internet.

Use Insert | Image. You can use a table to position your image on the page, if necessary.

Unlike with Word and PowerPoint, the image is NOT included in the file. You will need to upload the HTML page and the image.

10. Adjusting brightness, contrast and colours

All of this is done from Images | Enhance colors.

N.B. It may not be clear if you need to adjust the brightness or the contrast — try both.

Adjust the R (red), G (green) and B (blue) values if there is too much of one of these colours in your picture.

11. Removing red eye

Select the eye/pupil affected by clicking and dragging over it. Go to Images | Red eye reduction.

12. Taking a picture of your PC’s screen

To take a snapshot of your computer’s screen, press c, select Whole screen or a window under Capture area and then press F11 to take the picture.

Oops

As with many other programs, but esp. useful when editing images, press Ctrl-Z if something goes wrong and you want to undo your last action.

13. Getting hold of IrfanView

• IrfanView is available on Staff WTS at Start | Programs | Graphics Packages | IrfanView | IrfanView.
• If you have a stand-alone PC you can download it free from: ww.irfanview.de
• Unfortunately, there is no Apple Mac version.