ACTIVITY: web colours

For this activity you will need image editing software, such as Photoshop (for more information, see Image editing programs).
If you are not sure how to download images from the web, go to Downloading images.

• Download Image 1 to disk. It is currently saved as a high-quality JPEG.

• Open the image in Photoshop, go to 'File>Save for web' and select GIF format in the settings panel at right.

• Try the different palette options (in the drop-down menu beneath the GIF setting) and see how the image and data size change. Try varying the colour bit-depth (menu to right of palette settings) and dither settings (below palette setting).

• Download Image 2 to disk. It is currently saved as a 256 colour GIF.

• Repeat steps 2-3 above. See how using a lower bit-depth for graphics can reduce data size without compromising image quality.