Dark areas, inverted "negative" effect

[RA1D3N-205]

In many games for PSX, N64, Saturn, Dreamcast, some SNES, maybe PSP or even on all systems. The games are unplayable because dark areas look inverted or "negative" no matter which emulator I use.

Here some examples:

PSX
Alien Trilogy, SLES-00246
Medal of Honor, SLUS-00974
Medal of Honor - Underground, SLUS-01270
Tomb Raider 1-5 under water, German versions

N64
Both Castlevania, European versions

The 2 pictures clearly show the difference. The dark image shows how it should be. I deliberately set the brightness of the brighter image to maximum in order to better show the difference of the effect.

I found out that other users who used JELOS also had this problem. They fixed the problem with options to adjust gamma and other settings. I haven't found anything under rocknix yet.

Here is the link to it: https://www.reddit.com/r/SBCGaming/comments/15c6cjk/powkiddy_x55_owners_be_sure_to_adjust_your_gamma/

I use a powkiddy x55 with the 20240702 version, same problem on the 20240612 version

[XEntombmentX]

I have this same problem. You can see this very clearly in the dark areas around the main menu. In JelOS, I'm able to fix this by adjusting the gamma, contrast, etc., but since I can't do that in Rocknix, it's stuck looking like this.

[LaurensBosscher]

Requires testing but a workaround might be possible through sway using e.g:

• https://github.com/sentriz/wl-gammactld
• https://www.ddcutil.com/
• Redshift: Feature request: set gamma via output swaywm/sway#4302 (comment) or examples/gamma-control.c: add parameter to set different gamma for rgb swaywm/wlroots#1851 (comment)
• ICC Profile: https://wiki.archlinux.org/title/ICC_profiles (see 3.4 Wayland)

Having some sane defaults for the X55 will probably fix this issue for most users. Open question is, what is actually supported with libmali?

[LaurensBosscher]

@XEntombmentX @RA1D3N-205

As a workaround for Retroarch emulators you can use the misc/image-adjustment shader.

This shader allows for tweaking both gamma and contrast. It does have some performance overhead so it's not perfect and it'll probably require some experimentation to figure out the best settings but it should help.

[XEntombmentX]

Yeah, that may help in-game, but using Emulation Station in that state is horrendous, too.

[LaurensBosscher]

As a reference, instructions for the Retroarch shaders can be found below:

1. Start a game
2. Open the "Quick Menu" in Retroarch by pressing both joysticks
3. Navigate to "Shaders"
4. Turn "Video Shader" to "ON"
5. Navigate to "Load Preset"
6. Select "Misc" -> "Image Adjustment"
7. Go to "Shader Parameters"
8. Change the following:

• Target Gamma -> 2.40
• Monitor Gamma 2.00
• Saturation -> 1.50
• Contrast -> 1.15
• Black Level -> -0.10

9. Navigate back to the shader menu and pick "Save Preset"
10. Select Either:

• "Save Global Preset" to have this as the default for all Retroarch cores
• "Save Core Preset" to have this as the default for a specific system (e.g all PSX games)
• "Save Content Preset" to have this as the default for a specific directory (e.g all in the PSX directory)
• "Save Game Preset" to have this as the default for the specific game that you're running

Settings for 8 are a suggestion, you probably want to tweak them a bit to suit your preference.

[TheReaperUK]

Confirming i have this very same issue on a brand new 1GB version X55 and latest ROCKNIX Update.

[LaurensBosscher]

For reference, instructions have been added to the website: https://rocknix.org/devices/powkiddy/x55/#screen-calibration. Please refer people (e.g from Reddit or Discord) to here instead of Github.

[TheReaperUK]

For reference, instructions have been added to the website: https://rocknix.org/devices/powkiddy/x55/#screen-calibration. Please refer people (e.g from Reddit or Discord) to here instead of Github.

But this is not a REAL Fix and only Works on Libretro Cores, Standalone Emulators, Emulation Station and PortMaster Games still have This Issue and needs to be FIXED.

[aenertia]

Reminder; this is a community project and everyone working on it is an unpaid volunteer; doing amazing things with undocumented hardware.

[LaurensBosscher]

For reference, instructions have been added to the website: https://rocknix.org/devices/powkiddy/x55/#screen-calibration. Please refer people (e.g from Reddit or Discord) to here instead of Github.

But this is not a REAL Fix and only Works on Libretro Cores, Standalone Emulators, Emulation Station and PortMaster Games still have This Issue and needs to be FIXED.

As always, talk is cheap, patches are always welcome. Very much looking forward to your PR to fix this!