SCANNING IMAGES FOR YOUR WEBSITE

Evocity Internet Engineering provides document and image scanning service for website customers. If you would like to perform this task yourself, here are some guidelines:

The way you scan an image depends very much on what you plan to do with it. One of the first things you need to decide is whether the image is bound for print or the Web. Since the image pixels on a computer screen are bigger than the image pixels on a printer, take this into consideration when scanning. That is, digital images that look good on a screen may look fuzzy or "pixelated" when printed.

If you are planning to scan a picture from a magazine and post it to the Web, or send via e-mail, you can get away with a simple 72 DPI scan. Should you want to scan that same image and print it out on a color printer, then it's worth scanning at a higher resolution, anywhere from 200 to 600 dpi. The tradeoff, of course, is file size. A 72 DPI scan might be only 100 KB, whereas a 6-inch by 4-inch photo scanned at 300 DPI can produce a 15 to 20 MB image. If your scanner handles slides or negatives and you want to zoom in on a specific portion of an image, you may want to go as high as 2400 DPI! Then you're talking about Godzilla-sized files, which are measured in GZbytes.

When you first scan an image, your best bet is to start with a low resolution setting and work your way up. The default resolution might be 150 DPI - that's not a bad place to start. To use your scans for both printing and the Web, you will want to scan them at two different resolutions, at least. For computers, images scanned at 72 to 100 DPI will look fine. For printing on a color inkjet or laser, start at 200 DPI and work your way up. Your scanning software should provide options where specific DPI settings are available.

The next important setting you will make is the "output type," which describes what type of image you're scanning. These settings are pretty intuitive, and you will find that "black and white photograph" and "best color photograph" will be the best choice for most of your prints.

Now pick the output type. (Here's a closer look.)

Once you've lined up all the pictures you want to scan, and decided what resolution to use, it's a good idea to close out of other applications on your computer. The more RAM the computer can use, the faster the scans. Likewise, you should make sure there is enough room on your hard drive to store the scanned images; you'll be surprised at how fast these files fill up your drive. It's also smart to get in the habit of trashing scans that you don't plan to save.

Another way to save space and time is to crop pictures before you scan them. Most any scanning software will give you a tool to select a specific area to scan, usually by dragging your mouse around the portion of the picture you want.

After setting your resolution and output type, make sure that your print is lined up correctly on the scanner bed. A preview screen in the scanner application will show you how the image looks. Once the image is situated correctly, simply press the scan button and wait for the sensors to do their work. Depending on the resolution setting, a scan will usually take anywhere from 10 to 30 seconds.

Most scanner software will let you adjust the color, contrast, and other aspects of your image while scanning. If you have a copy of Photoshop, or another good image editing program, don't bother adjusting these elements with the scanner software. Graphics editing tools give you more control over the process and generally produce better, clearer results. If you really want to streamline your scanning, you can configure Photoshop to act as your scanning software.

After you scan an image, you need to decide how to save it. When you pull up the save menu, you'll see a choice of about ten file formats, everything from BMP to JPEG to TIFF. These formats break down into two basic groups: compressed and uncompressed ("lossless" in graphics jargon).

When you save a file in a uncompressed format — TIFF, BMP, PCX — it won't discard any of the data during the encoding. The advantage here is that you retain as much information as possible about the scanned image, and can compress it later, after you've adjusted its contrast, brightness, etc. The disadvantage of these formats is that they create very large files.

For the web, JPEG and GIF are the two most widely used formats. The upside is that JPEG and GIF create very small files. If an image is 4 MB to begin with, JPEG will compress it to around 50 KB with only minimal loss in quality. JPEG should be used for photographs, save GIF for crisp color art.

Images bound for a website should be kept under 40 KB. Web pages that have images larger than this take a long time to load. If you're going to send a JPEG over email, something on the order of 60 to 100 KB will work.

If you compress a file with JPEG or GIF and find that it's still too big, go back to the original file, reduce its size (dimensions), and then resave it. If you do this a few times, you'll begin to see the relationship between image size and file size. Photoshop also features a "Save for Web" feature, which let you preview your image under a variety of compressions.

For images that you want to print out, you should save them as TIFF uncompressed or BMP and use a high DPI setting (300 and up) when scanning them.

Contact Evocity™ Internet Engineering for assistance.