Tutorials & Tips

Scanning Tips

Images intended to be viewed on the web should not exceed a resolution of 72dpi (dots per inch). The more dots per inch (or, the higher the resolution), the more information there is crammed into each square inch. A higher resolution image will result in a larger file size. Although it will provide a better image quality, the superior quality will not be visible on the web, so you will be wasting web space for no reason. so, it's better to stick to 72dpi in order to save space. This will also help deter others from stealing your images for print work, as the low resolution will not provide an acceptable print quality.

Your scanning software will probably allow you to set a default resolution. It's tempting to set it at 72dpi, so that you will not have the added step of lowering it, but I have found that the final image quality is much better if the original scan is at a higher resolution. I scan artwork at 100% size and 300dpi.

Most scanning software will allow you to crop, lighten, darken, adjust color, descreen, crop, and flip. I prefer to do most of those things in with my image editing software, with the exception of descreening. When scanning printed material, like magazine images or newspaper articles, it is important to descreen. Otherwise, the scanned image will have a moire pattern. If your scanning software does not have a descreening tool, try scanning the image at a really high resolution. It's not a perfect solution, but it should get rid of most of the moire patterning.

Depending on your set-up, your images may be scanned directly into your image editing software. If not, you will have to find the file your scanned images were saved to, then open the images manually.

After rotating and cropping the image, I adjust the resolution and size. I scanned the image at 300dpi, which is much larger than I need for display on the web. The original file size was over 20Mb, which is just enormous.

By lowering the resolution to 72dpi and the height to 900 pixels, and using Photoshop's "save for web" function, the image is still legible, but the final file size is a mere 76Kb.

The final image can be seen here.

Note: I use Photoshop to prepare images for the web, but there are many other image editing programs out there that will work perfectly well. If you don't have to do fancy image editing, there is no reason to buy an expensive program like Photoshop. Paint Shop Pro is quite good, and relatively inexpensive. Irfanview, which is free, is another favorite of mine. Either of them has the capability to resize and alter the resolution of image files.

E-mail: shelly@cat-sidh.net
Copyright 2007 Shelly Couvrette