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Hue/Saturation/Intensity Filter

If a 3D video contains certain colors (like bright red or blue, for example), they should be desaturated with this filter before converting the video to (or viewing as) a red-blue (or cyan) anaglyph.

A screenshot of the filter:

Important Fact: You can _stack_ filters in VirtualDub, and this includes two or more applications of the same filter. This would be needed with this filter, for example, if you wanted to desaturate red by 60%, but other colors by 40%! BTW, the filters are stacked "progressively", with the first filter's effects applied to the image(s) first, then the second filter, third filter, etc. Knowing this, you have to adjust the saturation level of a stereo pair first (for example), _then_ apply the Interlaced RGB filter that converts the pair to anaglyph!

I loaded a BMP of a color wheel into VirtualDub to see if I could come up with any basic conclusions about the saturation settings. Here's a comparison of the color wheel with no adjustments (top screenshot) to a 50% desaturation of all the colors in the filter (bottom screenshot). This simply demonstrates what the colors look like at 50% saturation... many, if not most, videos will only contain a color or two that needs adjustment, and in that case, I only desaturate the colors that obviously need it, otherwise you get sort of a washed-out video. But... if you ever made a video of a color wheel <grin>, you would have no choice but to desaturate all the colors! At 50% saturation, most of the colors cause little to no retinal rivalry (clashing of the colors when looking through the red lens and the blue or cyan lens), but in my opinion, there is still a small amount in the red, the blue and the blue-green colors... not coincidentally, as that's the color of the anaglyph glasses lenses! So... if I were to desaturate a video that contained lots of red, I would probably desaturate only the red, but _more_ than 50%. On the other hand, if a video contained many colors that need desaturation, I might desaturate all (or most of) the colors by only 30%, making a compromise between washing out the video too much and retaining a small degree of retinal rivalry. Remember, since you can add (stack) two or more applications of this filter, you can really get picky with the saturation... but I usually don't ! :-) Since these are simple graphics and not photos, I felt I could get the point across by showing these as GIF's. If you want to do this experiment, yourself, I suggest you load a BMP of a color wheel into the filter and make your own conclusions by looking at the uncompressed preview :-) BTW, I rarely use the other adjustments in this filter for this purpose (desaturation for anaglyphs). I haven't found them to be of any use for this... correct me if I'm wrong!

The color wheel BMP opened in VirtualDub with no filter applied: (The left and right images are identical in this top screenshot)

The Hue/Saturation/Intensity filter applied with settings at 50% saturation to all the colors in the filter: