IMAGE SIZING: Determine the smallest display sizes (the size people see them on the monitor screen) you need for your images and scan them at no more than 72 ppi (pixels per inch).

Creating images for your homepage is not just a matter of getting a photograph scanned into digital form. There's a tremendous difference between the typical dpi resolution that photo labs and service bureaus normally provide their clients and what is useful for displaying on the Internet. Unless you inform the photo lab what the ppi and size requirement is for your scans, they will produce 150 or 300 dpi images at 100 percent size for you. These images will work, but the resulting large files will take much longer to download over the narrow bandwidth of the Internet. For example, a standard 3.5-inch by 5-inch snapshot scanned at 150 dpi would generate a file that is 1.15mb in size. Saved in the GIF file format, it would be approximatelt 240mb in size. Saved in the compressed JPEG file format (medium compression), it would be approximately 35kb in size. Even working with a the latest modems, a viewer will have to wait four to six seconds for the JPEG image to finsh downloading and rebuild itself on the screen. That is acceptable if your homepage has one or two images, but it is a tedious wait if the viewer has a slow modem or if there are many images on your page.

The ideal ppi for your images is 72 ppi. This is because of computer monitors' display resolution. The standard VGA monitor displays only at 72 ppi or less, regardless of any display setting. It doesn't matter if the viewer sets his display for Standard VGA (640x480), Super VGA (800x600), or higher. Your images will only display at that 72ppi (they'll just look smaller at, say, SVGA). There is a general misconception that a higher image ppi will increase image resolution, sharpness and clarity. This is true only for electronic printing. For display purposes only on the Internet, any additional pixel information in your homepage images above 72ppi is not used. There are other means the homepage author can employ to achieve the look of sharper details (see using sharpening filters below).

CROPPING IMAGES: Crop your portrait images to remove unimportant background information and to create smaller file sizes.

Unless you intend to show your Internet guests what the interior decor of your house looks like or what's behind you in the park, crop out the miscellaneous information. The two benefits that occur by doing that, is 1) you make your image file size smaller and quicker to load, and 2) by tightening into the portrait, you convey the impression that you're closer to the viewer. This little deceit creates the feeling in the viewer's mind that the image is sharper in detail, when really it isn't.

USE SHARPENING FILTERS: Employ sharpening filters only once; use it only when done with all other editing.

Sharpening filters will benefit most images by making them "appear" sharper by strengthening the contrast between distinct areas of colors. Even the best scans could use the application of these filters. But use them lightly and only once after all other editing functions have been performed, or once after resampling an image to make it smaller. The reason why is that these filters physically and permanently alter the pixels surrounding those distinct areas of color. Each application of the filters create a build-up of the sharpening effect. Extreme use (or an extreme setting) of the filters will produce artifical dark or light colored borders around those areas of colors. Used frequently or carelessly, the sharpening filters will detract from the natural look of a photograph and actually begin hiding image details.

GRAYSCALE MODE: Use Grayscale mode instead of RGB color if your original images are B&W or poor in color contrast.

If you have a black & white digital image, you can save the file as a grayscale image in the JPEG format. Because only one channel of color information (black) is required for a grayscale image (instead of the three channels required for RGB color), the file will be one-third the size of a color image. This naturally produces an even smaller JPEG file. Changing a color image deliberately to grayscale is also a good souluion for scanned images that are flat in contrast or inherently lacking in color depth; any color really doesn't show so you might as well change it to grayscale. Note: The GIF file format does not support grayscale mode.

CREATE THUMBNAILS FOR LINKS: Make thumbnail images to link to larger image files

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USING JPEG FORMAT: Use JPEG file format whenever possible.

JPEG (Joint Photographers Expert Group) was originally a compression scheme to produce compact files for storage. With the introduction of plug-ins and filters into programs to recognize them, the format has become a file format standard, especially on the Internet which benefits from it's quicker download time. The viewer's computer actually does the uncompression and rebuilding of a JPEG image onto the screen. Browsers like Navigator and Explorer only have to contend with moving the file from one server to another. Another advanatge is that JPEGs are 24-bit color capable, which means that an image can retain 16.7 million colors in them and accurate rendition of details. Although most workstations aren't set to display more than 256 colors, the additional color-bit information will provide photographic quality images for those computer owners who have the right hardware to view them. Compression can range from slight to very heavy with incremental decrease in image quality. Usually a "medium" or "good" setting for compression is adequate for Internet use.


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