PAL chroma merging?

A place for your artistic side. Discuss techniques and tools for pixel art on the NES, GBC, or similar platforms.

Moderator: Moderators

User avatar
HardWareMan
Posts: 209
Joined: Mon Jan 01, 2007 11:12 am

Re: PAL chroma merging?

Post by HardWareMan »

Any *.NES file?
User avatar
thefox
Posts: 3134
Joined: Mon Jan 03, 2005 10:36 am
Location: 🇫🇮
Contact:

Re: PAL chroma merging?

Post by thefox »

Looks like you forgot to include the binary, tepples, so here it is.
Attachments
palphase.nes
(24.02 KiB) Downloaded 377 times
Download STREEMERZ for NES from fauxgame.com! — Some other stuff I've done: fo.aspekt.fi
User avatar
HardWareMan
Posts: 209
Joined: Mon Jan 01, 2007 11:12 am

Re: PAL chroma merging?

Post by HardWareMan »

[MOD edit: fixed broken links]
Attachments
5769224.png
5782536.png
User avatar
thefox
Posts: 3134
Joined: Mon Jan 03, 2005 10:36 am
Location: 🇫🇮
Contact:

Re: PAL chroma merging?

Post by thefox »

Here's a really crappy photo of my CRT TV (2C07 PPU). From what I can tell, it looks like colors match up so that evenHue = oddHue+2 (with wrap around, of course). E.g. the even scanline of $15 is the same hue as odd scanline of $13. (Looking at the TV the colors match up better than in the photo.)

Which is funny, because in HardWareMan's cap it's quite clearly evenHue = oddHue+1.
Attachments
pal-phase-test.png
Download STREEMERZ for NES from fauxgame.com! — Some other stuff I've done: fo.aspekt.fi
User avatar
Eugene.S
Posts: 317
Joined: Sat Apr 18, 2009 4:36 am
Location: UTC+3
Contact:

Re: PAL chroma merging?

Post by Eugene.S »

It's my Dendy on PAL CRT (UA6538 PPU)
Attachments
palphase_CRT.jpg
tepples
Posts: 22705
Joined: Sun Sep 19, 2004 11:12 pm
Location: NE Indiana, USA (NTSC)
Contact:

Re: PAL chroma merging?

Post by tepples »

thefox wrote:Looks like you forgot to include the binary
Oops, my bad. There are two places I need to change the binary's filename when I import the project template: makefile and zip.in. I forgot the latter.

So it looks like Dendy does this aspect right and PAL NES does it half-@$$, just as with the CPU clock divider. Anything I need to add in a second version of this test?
lidnariq
Posts: 11430
Joined: Sun Apr 13, 2008 11:12 am

Re: PAL chroma merging?

Post by lidnariq »

Ok, so:
A PAL scanline is "supposed" to be exactly 1702.5 master clock cycles, or 283.75 chroma cycles.
The 2C07 (and it looks like UA6538 also, given HardWareMan's pictures) scanlines are 1705 master clock cycles long, or 284 1/6 chroma cycles.
We see the expected repetition of phase every 6 scanlines.

What's weird is, as far as I can tell, adjacent scanlines of all hues really shouldn't be ≈the same phase, and yet they seem to be.

Maybe a useful test would be to exchange the solid grey scanlines in tepples's test with some fixed color? That way we should be able to say that hue phase X on even/odd scanlines is the same as hue phase Y/Z on odd/even scanlines? Obviously will only be visible on the luma-only signal.
tepples
Posts: 22705
Joined: Sun Sep 19, 2004 11:12 pm
Location: NE Indiana, USA (NTSC)
Contact:

Re: PAL chroma merging?

Post by tepples »

I'll take this as a feature request to let the user change the background palette between $00 and any color $11-$1C. Is that what you want?
lidnariq
Posts: 11430
Joined: Sun Apr 13, 2008 11:12 am

Re: PAL chroma merging?

Post by lidnariq »

Sure?
I guess that's not all that different from the original test I made, although it lets you compare more colors simultaneously.
tepples
Posts: 22705
Joined: Sun Sep 19, 2004 11:12 pm
Location: NE Indiana, USA (NTSC)
Contact:

Re: PAL chroma merging?

Post by tepples »

Exchange this.
Attachments
palphase-0.02.zip
Fixed missing binary; added left and right to change background color; boxes are not as tall
(19.01 KiB) Downloaded 378 times
User avatar
HardWareMan
Posts: 209
Joined: Mon Jan 01, 2007 11:12 am

Re: PAL chroma merging?

Post by HardWareMan »

Here we go.
[moderator: recovered images from web.archive.org]
Attachments
5823521.png
5820449.png
5821473.png
5810209.png
5811233.png
5814305.png
5815329.png
5812257.png
5807137.png
5805089.png
5794849.png
5791777.png
5798945.png
Sik
Posts: 1589
Joined: Thu Aug 12, 2010 3:43 am

Re: PAL chroma merging?

Post by Sik »

thefox wrote:Here's a really crappy photo of my CRT TV (2C07 PPU).
What did you use to take the photo? In my experience phone cameras tend to be good at taking photos of CRTs (apparently you need a crappy camera to take a good pic of a CRT, who would have thought)
User avatar
thefox
Posts: 3134
Joined: Mon Jan 03, 2005 10:36 am
Location: 🇫🇮
Contact:

Re: PAL chroma merging?

Post by thefox »

Sik wrote:
thefox wrote:Here's a really crappy photo of my CRT TV (2C07 PPU).
What did you use to take the photo? In my experience phone cameras tend to be good at taking photos of CRTs (apparently you need a crappy camera to take a good pic of a CRT, who would have thought)
iPhone 4
Download STREEMERZ for NES from fauxgame.com! — Some other stuff I've done: fo.aspekt.fi
User avatar
Eugene.S
Posts: 317
Joined: Sat Apr 18, 2009 4:36 am
Location: UTC+3
Contact:

Re: PAL chroma merging?

Post by Eugene.S »

I will upload new test pictures at evening today
User avatar
HardWareMan
Posts: 209
Joined: Mon Jan 01, 2007 11:12 am

Re: PAL chroma merging?

Post by HardWareMan »

Well, I took out my old monitor, which is used in the 90's. Do not look at the geometric distortion - I'll fix them later. The main feature of this monitor is that it is PAL decoder built on a good old TDA3510. This "warm tube" analog PAL decoder that utilizes the 64mks delay line. Therefore, the result really depends on the content of neighboring scanlines. In the new digital decoders, each scanline can be processed separately, although Avermedia shows almost identical to TDA3510 results.
UMC UA6538:
5823602.jpg
HA6538:
5783665.jpg
5789809.jpg
[moderator: recovered images from web.archive.org]
Post Reply