Irlam Picture

This picture was scanned by Irlam Instruments' 24-bit hand scanner reviewed in this issue. It is saved as a JPEG (Joint Photographic Experts' Group) file in order to minimise the amount of disc space used, yet preserve all of the image information in 24-bit colour. JPEG is a lossy compression technique, which means that when compressing a picture using the JPEG method you can specify an image quality level that determines the amount of detail that is retained. It is intelligent in that the detail it removes is that least likely to be noticed by the human eye, so minimising the negative impact on the appearance of the image. There is a trade-off between image quality and appearance, although even at 100% image quality, the compression achieved is still impressive.

The image here is stored using 100% image quality, it is therefore exactly the same as the original scanned image. To view it, you will need a recent version of ChangeFSI. The RISC OS 3 Support Disc contains a suitable version. If you have no hard disc, or you have less than 800K free on your hard disc, you will need to copy the !Scrap directory from this disc onto a blank 800K or 1600K floppy and then run it. Run ChangeFSI and set the following options in the dialogue boxes that are accessed from ChangeFSI's icon bar menu:

Scaling: All of the option buttons should be off except +90 and Scale 1:1 1:1.

Processing: All of the options should be off.

Output: Select Use current mode and, if it is present, Colour.

Now select a 256-colour or higher mode. You can then double-click on the !IrlamPic icon and drag the Mountain file to the ChangeFSI icon. The hourglass will appear and after a delay, which could be a few minutes on an ARM 2 machine with no hard disc, the picture will be displayed in a window. You will then be able save and zoom the sprite and read information on the source file.