Sometimes you may find that there is a picture you would like to include on your web page that is simply too big to fit. Photographs from your camera or mobile phone are usually large images that will take up a lot of space on the page.

There are many ways to approach this – here is one way, using a free tool called the GNU Image Manipulation Program, or GIMP for short. GIMP is a powerful and complex image editing program. It can be quite daunting to use, but we will just look at two simple functions for now: resizing pictures and cropping pictures.

Once you have installed GIMP (you can find a link on the Downloads page), open your image file either by right-clicking the file and selecting “Open in GIMP,” or using GIMP's File menu.

The window that shows your image will have the resolution in the title bar. This shows how many pixels tall and how many pixels wide your image is.

Let's say you want to make the image half as big. (Always scale images down, not up: if you blow an image up the quality will get worse and worse.)

Click “Image” in the menu bar, and select “Scale Image…” A dialogue box will pop up. It will show, among other things, the image’s width and height in pixels. (You can use the dropdown menu on the left to show the size in inches, if you prefer.)

First, click the chain icon to the right-hand side of the measurement boxes. Make sure the chain icon does not look “broken.” This setting means that if you reduce the width of the image, the height changes so that the “aspect ratio” of the image stays the same. In other words, the image will not look stretched out of shape, just smaller.

Simply change the height or width of the image to the desired value and click the “Scale” button.

Now let's say you only want part of the image – you would like to “crop” the rest of it away. Here's a simple way:

First, look for GIMP's toolbox. It looks like the image below. If you can't see it, click “Windows” in the menu bar and select “Tools” to show it.

Click the rectangular selection tool in the toolbox. It looks like this:

Click and drag a box around the part of the image you would like to keep, then click “Image” in the menu bar and select “Crop to selection.”