[Coco] CoCo3 Video Player Version 2 Demo

[John W. Linville]

Right, the grid-like dots are an artifact of the "ordered dithering"
process used to approximate the original colors using 16 Coco3 colors.
A different dithering algorithm might produce a different pattern
(or no pattern, but a constant "glitter" or "firefly" effect).

You can use a "best match" algorithm for the colors and avoid the
dithering, but that tends to produce a strange, cartoon-ish effect
(similar to those E*Trade commercials or an Obama campaign poster).
Also, this can produce a loss of detail in an area with a number of
similar colors in the source image.  The dithering can cause loss of
detail too, but on balance the effectively larger range of perceived
colors seems to make dithering the better choice in most cases -- YMMV.

Obviously, if you were to produce cutom video for a project (especially
an animation) then you could more precisely match the source palette
to the available CoCo3 colors.  Or in some cases you might alter the
CoCo3 palette in use to better match a particular video.  In my case,
I have a variety of videos mostly from YouTube and DVDs.  They take
a long time to process and I don't have a good algorithm for picking
a "best" palette for tens or hundreds of thousands of frames from
a video.  So, I have a palette that I picked for good coverage and
that seems to give acceptable results across a large range of videos.

John

On Fri, Apr 15, 2011 at 01:33:52PM -0700, Steve Bjork wrote:
> In the video source that this demo was transcoded from has red
> drapes as the background on the title screens .
> 
> The red lines are where the red drapes were a bit brighter.
> 
> Remember, he has only 16 colors to work from.
> 
> Steve
> 
> On 4/15/2011 1:15 PM, Arthur Flexser wrote:
> >I wonder what the cause is of all the vertically-aligned dots that mar the
> >appearance of the picture, and if any algorithm could be developed to reduce
> >their presence during the preprocessing of the individual frames?
> >
> >Art
> 
> 
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-- 
John W. Linville		Someday the world will need a hero, and you
linville at tuxdriver.com			might be all we have.  Be ready.