So you've bought that great scanner and high-end digital camera and are ready to create a terrific presentation with your very own images. But even though pushing the scan button is simple, scanning smartly takes a bit more planning. Knowing the basics about color depth, dots per inch (dpi) and scaling can all make your next scanning experience simpler and can result in a more efficient file size. Before starting any scan, it's critical to know how it will be used in your presentation. When previewing your scan in your scanning software, take the time to set up the following attributes correctly:
DPI/Resolution: The amount of detail/resolution you want in your scan is controlled by the DPI (Dots Per Inch) Setting. By not telling your scanning application the specifics of the image you're scanning, you could wind up with an unwieldy 10Mb image instead of a more manageable 100K file. If your presentation is being projected with 35mm slides (which have 4,000 lines of resolution), scan at 200 dpi (dots per inch). For computer-based (screen or LCD projected) presentation, scan at a resolution of 72 dpi.
Size/Physical Dimensions: Similar to DPI/Resolution, setting the physical size of your scanned image in the scan preview mode (before proceeding to final scan), will ensure your image isn't too small or too large. If you're working with a presentation for on-screen use, use "pixels" for units of measurement. If you're projecting at 1024x768, your scan size need not be any larger than the projected size. If your presentation is going to be printed, set the dimensions for a resolution of 300 DPI and the physical units of measurements in inches or centimeters.
Color Depth: The numbers of colors in your scan will also affect file size. If you're scanning a photograph, scan at 24-bit or 32-bit (millions of colors) resolution. If it's a logo or illustration with just a few colors, try an 8-bit scan.
File Type/Save Options: JPG are one of the most common format for images. If scanning a logo or image with just a few colors, the GIF format is often preferred, as it can produce smaller file sizes and doesn't "compress" the image like JPGs. Also,rather than using the clipboard to cut and paste into PowerPoint, it's smarter to use the Insert Picture command, resulting in much smaller file sizes.
Most scanning preview software will show the estimated file size of the final scan. Use this as a guide to produce the smallest sized file, so that your file import into PowerPoint at 100% of the desired size and that no resizing within PowerPoint is necessary. One good technique for scanning is to scan at a high resolution and use a photo editing tool (Photoshop) to re-size the image down to the desired resolution and dimensions. This way, you're sure to get the perfect sized image imported into your presentation!