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Karoshier
Account closed
Registered: May 2010
Posts: 15 |
Which koalas would you use to test a palette?
I'm coding a PC tool specific for C64 graphics editing, with an option to generate the global palette according to pepto findings and TV adjustments in the YUV domain.
I would like to use some pure koala images against which to test the outcome of this generator. Since I'm no graphician at all, I'm asking you guys which images do you think are best for this purpose according to your experience.
A warm thank to anybody providing pointers, ideas or suggestions. |
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chatGPZ
Registered: Dec 2001
Posts: 11108 |
i used the following for crosschecking my pal stuff:
Play With Colors 1
Play With Colors 2
Weeee!
emusuxX0r
(and my lousy http://hitmen.c02.at/temp/paltest.prg)
these are especially useful to check wether odd/even lines chroma mixing works correctly. |
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Karoshier
Account closed
Registered: May 2010
Posts: 15 |
Thanks Groepaz! Your pointers are indeed very interesting.
As far as I understand, speaking of graphics editors, the line intermixing effects of the colors on a standard CRT are only emulated in Timanthes.
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Mr. SID
Registered: Jan 2003
Posts: 421 |
PAL line blending is not a CRT artifact, it also happens on LCD PAL TVs and monitors. |
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andym00
Registered: Jun 2009
Posts: 44 |
I've been meaning to ask about this, but on Groepaz's page about (maybe it was somewhere else[1]), he mentioned that the reason for the differing colours depending upon the order of the colours was because VIC doesn't generate full 180 degree phase shifted versions of the colours ? Hence why the same colours but ordered differently generate two different blended colours..
Is there anywhere I can find the (incorrectly) phase shifted colours that are outputted ?
[1] Ah.. It was on the 'Joes 120 colours' thread.. |
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chatGPZ
Registered: Dec 2001
Posts: 11108 |
the amount of phase shift directly relates to a pot in the modulator inside the c64, so its different for every c64 :) |
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Karoshier
Account closed
Registered: May 2010
Posts: 15 |
So, if I understand correctly from video-color.c and associated files, the phase of the chroma signal on odd lines is altered by a variable amount which ranges from -45 to +45 degrees depending on how the trimmer near the VIC-II is set.
This means basically that the hue is different on odd lines, is it?
But, if this reasoning is correct, a solid color should appear striped horizontally and that is not the case.
I guess I'm missing something or I'm completely off-track. :P |
