Victor Engel's No Dither Netscape Colors

Example Images

This document will show example images that have been optimized using the 6x6x6 palette.

This is an image of the standard Windows colors. No special processing has been performed on this image.

This is the same image after applying the Netscape palette setting each color to the nearest color in the Netscape color cube.

If you have a good monitor, and your browser will display all the colors presented in this document, you may notice a slight color shift between this image and the previous one. However, the shift is slight. If you are using an 8 bit system running Netscape, you will notice that the dithers disappeared in the second image.

This is the same image after using Paint Shop Pro to apply the Netscape palette using error diffusion.

All the colors in this image are Netscape colors, but there is a dither still visible because the colors were dithered in the process of applying the palette. If you look very closely, you will see that the dither patterns are slightly different from the dither pattern created by your browser when displaying the first image (assuming you are viewing this page on an 8 bit system). This is because the dither pattern in the file is being used as saved. If you are clever, you can take advantage of this by placing individual pixels strategically. This would most likely be valuable when designing icons.

Now let's try the same techniques on a photographic image. This is a picture of me next to my car.

This is the raw picture saved in jpg format:

This is the same image after applying the Netscape palette using error diffusion.

All the colors in this image are Netscape colors, but there is a dither still visible because the colors were dithered in the process of applying the palette. If you are using a 256 color display, this image probably is very similar to the previous one because your browser has to dither the first image. If you have a true color display, the previous one looks much better than this one.

This is the same image after reducing the color depth to 256 colors using an adaptive (optimized) palette.

If Netscape's palette changed on the fly, this image would look the best on a 256 color display. With Netscape 2.0 or later, you can right click on the image and select View to view the image using its own palette. You may have to click Reload if the image is simply loaded from your cache. If you have a 256 color display, you will notice a marked improvement when viewing the image this way. This is not possible with the JPEG image, above.

This is the same image after applying the Netscape palette setting each color to the nearest color in the Netscape color cube.

Distracting banding occurs in the image.

In summary, using the 6x6x6 color palette to optimize images for display on the Web is useful for image containing a limited number of colors or images captured from Windows programs, for example. However, this technique does not benefit the display of photographic images. Photographic images should be presented as JPEG or GIF with an adaptive palette in most cases. I hope this page has been a help to you. If you find it helpful, please tell others about it. If you have any questions, comments, or suggestions, email the author, Victor Engel at victor@victorengel.com.

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http://www.onr.com/user/lights/netex.html