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Joodas
Registered: Oct 2011 Posts: 8 |
Joe's 136 colors technique
Hi all,
I am looking for information about Joe's 136 colors technique. Any links will be appreciated.
Thank you for help |
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Skate
Registered: Jul 2003 Posts: 491 |
it's just mixing colors like checkers
1: Color 1
2: Color 2
12121212
21212121
12121212
21212121
12121212
21212121
12121212
21212121
and you have a mixed color. 16x16 there are 256 color combinations. but!
S: Solid Color (Original C64 Color)
X: Mixed Color
M: Mirrored Color (same color with inverted checker pattern)
+ 0123456789ABCDEF
0 SMMMMMMMMMMMMMMM
1 XSMMMMMMMMMMMMMM
2 XXSMMMMMMMMMMMMM
3 XXXSMMMMMMMMMMMM
4 XXXXSMMMMMMMMMMM
5 XXXXXSMMMMMMMMMM
6 XXXXXXSMMMMMMMMM
7 XXXXXXXSMMMMMMMM
8 XXXXXXXXSMMMMMMM
9 XXXXXXXXXSMMMMMM
A XXXXXXXXXXSMMMMM
B XXXXXXXXXXXSMMMM
C XXXXXXXXXXXXSMMM
D XXXXXXXXXXXXXSMM
E XXXXXXXXXXXXXXSM
F XXXXXXXXXXXXXXXS
Number of Solid Colors = 16
Number of Mixed Colors = 120
Number of Mirrored Colors = 120
Since mirrored colors are duplicates, there are 120 + 16 = 136 colors. |
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Graham Account closed
Registered: Dec 2002 Posts: 990 |
There's also true color mixing when using different colors of with the same luminance:
AAAAAAAAAAAAAAAA
BBBBBBBBBBBBBBBB
AAAAAAAAAAAAAAAA
BBBBBBBBBBBBBBBB
AAAAAAAAAAAAAAAA
BBBBBBBBBBBBBBBB
AAAAAAAAAAAAAAAA
BBBBBBBBBBBBBBBB
which results in a slightly different color than:
BBBBBBBBBBBBBBBB
AAAAAAAAAAAAAAAA
BBBBBBBBBBBBBBBB
AAAAAAAAAAAAAAAA
BBBBBBBBBBBBBBBB
AAAAAAAAAAAAAAAA
BBBBBBBBBBBBBBBB
AAAAAAAAAAAAAAAA
Although using the same colors :)
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Skate
Registered: Jul 2003 Posts: 491 |
My favorite picture using this technique is Mermaid's Self Portrait with Unicorns .
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Graham Account closed
Registered: Dec 2002 Posts: 990 |
And Oh Noes, They Be Stealing My Bench |
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redcrab
Registered: Aug 2011 Posts: 33 |
The downside with crosshatching is that you tend to get big color-differences depending on where on the screen you have it, resulting in horizontal stripes, often in blue-ish and yellow (when watching on a tube television at least)
"Waiting for inspiration" by Carrion (very nice picture otherwise) looks like a zebra. -At least on my tv's.
Do anyone know WHY it is like that? |
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chatGPZ
Registered: Dec 2001 Posts: 11147 |
"The downside with crosshatching is that you tend to get big color-differences depending on where on the screen you have it, resulting in horizontal stripes, often in blue-ish and yellow"
its related to the effect graham mentioned - also in a checkerboard pattern PAL effects apply. |
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Perplex
Registered: Feb 2009 Posts: 254 |
Here's a photo of a TV with a C64 connected, demonstrating the difference between odd/even mixing:
Rows 1 and 4 contain the plain colours. Row 2 is mixed with colours from row 1 on even lines and colours from row 4 on odd lines. Row 3 is mixed with colours from row 1 on odd lines and colours from row 4 on even lines. |
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redcrab
Registered: Aug 2011 Posts: 33 |
But I'm still puzzled by that hires thing. Here is a photo of a TV showing checkerboard patterns with light gray and white. The upper one starts with a white pixel in the upper left corner, and the lower one is inverted. (gray in upper left)
As you can see it alternates between blue and yellow for every character row. It is in fact exact every char even though the camera seems to bleed a bit too. And the lower one does the same, but the opposite way. This is not logic to me.. But I might just be stupid :)
(this pattern may also be familiar to some from the sky in mr sids version of canabalt) |
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Graham Account closed
Registered: Dec 2002 Posts: 990 |
The vertical green/red bars effect only happens when using composite. If you use S-Video, that effect will not happen.
It's caused when the composite signal is seperated into a luma and a chroma signal again by using a low/high-pass filter with a cutoff frequency ~4 MHz. Since the filter doesn't work perfect, parts of the hires luma pixel pattern will still leak over to the chroma signal.
~8 MHz pixel clock with alternating pixels = ~4 MHz frequency. Remember: Chroma color carrier has 4.43 MHz.
The reason why the pattern is fixed to character sizes is simple. Both, pixel clock and color carrier clock derive from the same master clock: 17.734475 MHz. Divided by 4 it's exactly the PAL color carrier frequency of 4.43361875 MHz, divided by 18 it's the C64 system clock of 0.985 MHz. C64 system clock * 8 is the VIC2 pixel clock of 7.882 MHz. So there is an integer ratio between color carrier and pixel clock of 16/9. :) |
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Monte Carlos
Registered: Jun 2004 Posts: 351 |
I give it the name "Geos Pattern" |
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