Here are a few things to know about Anti-aliasing, Transparency, Halos, and Drop Shadows in graphic files. The information below will help you when it comes to placing a request for an animated signature, so please read the info before sending in your your requests.

•  About Pixels. •  About Transparency. •  About Anti-aliasing. •  About Halos. •  About Drop Shadows. •  Text Samples.

Pixel: Is a Picture Element - a single point or unit of programmable color in a graphic image or computer display. [ Back ]	1.
Transparency: A GIF file allows you to create an image with transparent area(s) by selecting only one color to be the designated transparent color. Every pixel (single point) in the image that has that color will be invisible. Image #2 above has not been saved with a transparent background, thus the blue background is visible. Image #3 above has been saved with a transparent background, blended with a black color, so the blue background is not visible, thus no "halos" appear. Image #4 has been saved with a transparent background, blended with a original blue background color that does not match this pages black background, so the blue background is not visible, but "halos" are visible. Partial transparency is not allowed in a GIF file - either a pixel is transparent, or it isn't. [ Back ]	2. 3. 4.
Anti-aliasing: This is the smoothing of the image by adjusting pixel positions or setting pixel intensities so that there is a gradual transition between the color of a line and the background color. (see Image #5.a). Since pixels are square points, an image that is not anti-alised will look like stair steps - the "jaggies".(see Image #5.b). Anti-aliasing is done, by blending the edges with pixels that gradually get lighter and lighter until the edge is transparent. (see Image #6). [ Back ]	5. 6.
Halo: Is the color that shows up in an image that they has not had its "anti-aliased" areas converted to blend with the background color. The "halo" is located directly in between the image's edge and the background color. As mentioned above, pixels in a Gif image are either transparent (0% opaque) or a solid color (100% opaque). When saving a Gif file, a lot of programs give the option of handling partial transparent pixels in the image by allowing to you select a single color that you want the partial transparent pixels to be converted to. In Image #6, the red button was blended with a white background. When the button is placed on a gray background (see Image #7.a.), you see what is called the "halo", effect. When the same graphic is placed on a white background (see Image #7.b.), you do not see the "halo", since the edges blended with the white background when converted. [ Back ]	7.
Drop Shadow: The same blending principle applies to images with drop shadows. The "halo" will depend on the size of the shadow and how well it was blended with a color matching the background. Again, Image #7 was blended with a white background. When placed on the gray background, the "halo" really looks bad. (see Image #7.a.). When placed on a white background, the "halo" is not visible. (see Image #7.b.). [ Back ]	8.
Text Samples: Image #9 shows text samples for your comparison. Image #9.a. shows a Gif image that has had the edges blended (converted) for placement on a white background. The the remaining areas outside of the blue text are transparent. You will notice that while it look good on the white background, the part over the gray background does show a "halo". Since the images partial transparent pixels were converted, the text retains its smooth edges because the "anti-aliasing" has been preserved. Image #9.b. shows the same Gif, but this time the edges have NOT been blended (converted). It can be placed on ANY color background, but please note how this image shows the "jaggies". The areas outside of the blue text are completely transparent. Since the images partial transparent pixels were NOT converted, the text loses its smooth edges because the "anti-aliasing" has NOT been preserved. Image #9.c. does NOT have any transparent areas. The text is on a completely white background. As a result, the white background in the text image is visible when placed on the gray background. [ Back ]	9.

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Page added on 06-15-2002