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Author Topic: ROM Hacks to Disable Dithering in PS1 Games  (Read 1843 times)

FiZiX

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ROM Hacks to Disable Dithering in PS1 Games
« on: February 21, 2018, 11:16:20 am »
Hello All,

Has there been any discussion here of removing dithering from certain PS1 games? I searched the forum but didn't see anything. In case you're not familiar with the topic, there are some examples here:

http://www.chrismcovell.com/psxdither.html

I know that some PS1 games benefit from dithering but, IMO, most look worse as a result. The effect seems especially useless on 2D games (like Castlevania: SoTN).

I wanted to bring this discussion to the RH forum because there are some very talented ROM hacker / designers here whom I thought should be made aware of this "feature". Perhaps this change wouldn't warrant a separate ROM hack for most PS1 games but may be a nice extra to add to existing improvement or quality hacks.

Best Regards,
FiZiX

Valendian

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Re: ROM Hacks to Disable Dithering in PS1 Games
« Reply #1 on: February 21, 2018, 10:18:03 pm »
You need to modify the GPU Rendering Attributes which is command GPU0(E1).

Search for the following memory mapped IO address 0x1F801810 it will probably appear similar to the following
Code: [Select]
  lui     r4, 0x1F80     #
  lw      r3, 0x1810(r4) #

modify the code so bit 9 is cleared
forgot to add that you need to find the references that write 0xE1xxxxxx to that port address (E1 command).
« Last Edit: February 21, 2018, 10:24:14 pm by Valendian »

weissvulf

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Re: ROM Hacks to Disable Dithering in PS1 Games
« Reply #2 on: February 23, 2018, 06:46:35 pm »
Interesting information to have. I would think dithering has become more of an issue since the rise of pixel-perfect LCDs.

FiZiX

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Re: ROM Hacks to Disable Dithering in PS1 Games
« Reply #3 on: February 26, 2018, 08:50:57 am »
Interesting information to have. I would think dithering has become more of an issue since the rise of pixel-perfect LCDs.

I think you're right, although I can see the checkerboard dithering pattern on my CRT with RBG input if I look for it.