Quote:
Originally Posted by DaleDe
In my experience you don't want to dither too early if a all. Dithering fills the image with little white or black dots to try and achieve additional gray levels. Once done it is not reversible. Usually I try to avoid dithering but if I need it I reduce the colors to 256 and then grayscale prior to attempting any dithering. I will also try and balance the image so that everything is not at one end of the darkness spectrum. It is a bit of art but the resutls can be pretty good. I usually don't drop below 16 levels and let the device itself do the final reduction if needed. After all you might buy a better device in the future.
Dale
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I too first place the image in grayscale. It's a very (very) bad idea to try to reduce colors on a color image ... unless you are trying to posterize and you don't mind getting some really funky results.
I never dither until I am absolutely satisfied with the contrast in the image. In addition, I always work on a copy of my original image. I never do anything to an image that cannot be undone.
However, dithering can be undone by any graphics program with an undo feature. In addition, most will allow you to preview the dither before you do it.
Since I will not be putting thousands and thousands of pictures on my e-book, I don't much worry about taking the images all the way down to 4 levels. If I want to take the same images and make them 16 levels some day because I've gotten a different reader ... I'll do it then. It takes less than 30 seconds for me to reduce an image. Further, it can be done in certain programs as a batch process (both PSP and PS allow for this).
Having the e-book determine how it is going to display the additional levels of gray that are beyond its capacity may work for you. I prefer the control that comes with knowing exactly what will be displayed, but then graphics are my passion.
In fact, I noticed when I downloaded the Beatrix Potter books from PG, that the images display very badly on the Kindle. I doubt they are much better on a 16 level display. That is why I am now preparing my own editions of these books, with illustrations that are (I hope) optimized for the Kindle.
Hey .... you know, some people are anal about justification, others about the color of their e-book. I am anal about graphics.