by MIA JOHNSON

Websites have become increasingly important for artists. This column provides basic information to help artists and galleries prepare for online exhibition.

Galleries and artists use digital pictures of artwork for many different reasons, including printed invitations, advertisements, website thumbnails or larger web images. A much higher resolution image is needed for printing than for web images. Artwork should be photographed as high-resolution images so smaller versions can be made later. On the web, for example, images are displayed at 72 pixels per inch, which is less than a quarter of the resolution required for printing (300 pixels per inch).

Here's a guide of recommended values for digital cameras.

To get an idea how large an image will look on a website, right-click with the mouse on any website image, open "Properties", view the dimensions, and compare them to this chart.

Scanners take pictures of photographs using the exact dimensions of the original. If slides are being scanned, the scanner takes a picture of each slide at real size (1 x 1.5 inches). The only way to get a larger image is to scan using as high a resolution as the scanner allows. For photos, the scanner resolution should be at least 300 pixels per inch. Slides require a scanner resolution of at least 1200 and preferably 2400 or 4800.

Once the image is in Photoshop, check the Image/Mode to be sure the colour is set to RGB, which is computer colour. Alternatively, images should be saved in CMYK if they are going to a printer. Files sent to clients or web designers must be less than 1 MB for simple email transfer, or transferred using CDROMs.

Under copyright law, copyright is automatically assigned to any file as soon as it is first created on a computer. For more information about authorship, file information about the author and source can be added to images in Photoshop using File/File info. For those concerned about protecting their work, consider using an object identification system such as one found at http://www.doi.org. This system adds invisible data to files that allows them to be tracked anywhere on the Internet.

A final important factor to consider is the storage size of each image. Files on websites should be less than 50kb each; in fact, an entire page of images should add up to 50kb. This means that each thumbnail file should be 10kb or less. Image sizes can be reduced in Photoshop using File/Save for Web. Set the view to "2-up" to preview the results of the compression. Move the Quality slider down until the second image is just above the threshold of fuzziness. Note the file storage sizes displayed along the bottom. If the thumbnails will be linked to larger images, a second file will need to be made for each thumbnail. Larger images that open in a separate window can be up to 50kb each.

Mia Johnson has reviewed art exhibits for Preview since 1989 and is the owner of www.black-box-media.com, a web design company in Vancouver, BC. She teaches Multimedia and Human Factors at Kwantlen University College.