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Posted By

MMS
on 2017-01-08
02:06:33
 Re: VDC Challenge!

Thank you :-)

Only very few SW tools used, so it was a kind of "spartan approach." happy
Below I give some details, not only for the experts happy

-I used just Irfanview and MS Paint as PC tools. And certainly Istvan's converter.
-With Irfanview I scaled down the pictures to 640x400 or 960x600 and used the slower Lanczos filter to get a better result. Nemo picture was so good, it required no modifications at all.
-If the original JPG picture was too noisy, I reduced the variations in the picture it with the median filter with lowest setting. It generates more "planes" with the same color. But it greatly reduces over-dithered +4 pictures, as the small whitish dots force the converter to generate noise and strange colored pixels.
The effect of median filter is most visible on the Tuhankhamon picture.
-Last step: usually I reduced color depth,hoping that it will be close to the Plus/4 palette. I usually step down to 256, but if possible, try 64 colors only.

Then I checked it with the converter, if I could prevent the dithered background. T

Usually this was enough to have a good base for converter.

Then only the Dithering method, their parameters, and usually the saturation had to be finetuned.
For me Jarvis and Stucki provides the best results, I hate Bayer and disilike FloydSteinberg.

If I found bad pixels at really bad place, I stepped back to MS Paint, and made small correction with brush and rubber.
-In one case I made full background recolor (Parrot), because background was completely dithered and looked crap. So I removed with hand (on the edges of parrot pixel by pixel) the background in MS Paint, and recolored the whole background to a color seemed close to a Plus/4 color.
he third green (turquize?) was the right one. BTW I had a other very nice parrot with purple background, but two parrots would be just too much of them in one slideshow happy (I really like these cute little dinosaurs happy )
-The Girl eyes need to be corrected in the same way, as there was a big chaos inside happy (as in the real life, eheheh). The hair was also finetuned a little, and eliminated the bad pixels of the backgroundpixels by hand.
-Strange enough, but one of the most complex one was the Astronaut, although it is almost black and white. A lot of small colored dots appeared on the Moon. But the suit had red buttons and an americal flag I wanted to keep in color, and if I reduced saturation, they turned grey. So I made the picture outside of the astronaut real greyscale in Irfanview, and reduced the saturation only to that level the US flag still recognizable.

Pictures saved with the highest 9 compression leved, with M2 setting. This is well supported by the player module wrote by Istvan.
M2 is lossless compression and greatly reduces the size of saved pictures, and on 1551 they load really fast
(remark: at the time of my Conan Comic slideshow I did not use compression extensively (afraid that it will result quality loss, like JPG), that's why only very few pictures fit to the disk. With my current knowledge the Conan release would be with much better quality and much more pictures)



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