black levels mismatched/losing details (Washed on fullrgb hdmi)

[johngarcia000]

Hi I got colors issues and mismatch black levels on SNES 1CHIP01. My SNES is plugged using C-SYNC Scart on my 4K Samsung QLED Q60T tv using GBS Control. 960p recommended resolution for NTSCs videogames comes washed out (gray bars around image) and I cant' change black level on TV playing SNES, its autodetect as Normal (full RGB) instead Low black level (limited). 1080P resolution seems ok on black level (low) but theres something wrong about colors, seems a bit oversatured on green, green seems a mix (green-yellowed) I can notice well on Super Mario World, map screen and tubes. Tubes and maps should be dark green (correct me if i'm wrong) and appeared as light green but a bit over bloomed. I cant explay very well but notice there are videos on internet about GBS that has the same color issues.

I got 2 LGS TVs 1080p, and colors works fine on 1080p resolution playing SNES - DARK GREY as intended, but on 960p happens the samething on SNES. I noticed 1080p is a bit dark compared 960p.

OBS: my 4k tv is good, tested another media content with no problems. My SNES is good - C-SYNC good cable.

https://www.youtube.com/watch?v=XJePetiCaN0&ab_channel=GSJ1980

Someone could help-me? (sorry my bad english).

[ramapcsx2]

It seems like a problem with the TV trying to force the wrong black level. It should always be "full RGB", not limited!

[johngarcia000]

It seems like a problem with the TV trying to force the wrong black level. It should always be "full RGB", not limited!

But Fullrgb (or normal) looks always washed on GBS Control, even on startup factory settings. I use HDMI. Any Resolution looks clearly whashed if use fullrgb. GREYED all around image. I'v testes with 3 tvs, same results. Without using GBS control, plugging console diretc to Retroscaler2x or direct component cables PS2 fullrgb looks right, not whashed. How to solve it?

Obs: My GBS is blue version 1CHIP China Aliexpress from Retroscaler. I update using your firmware from september 2023 (because someone posted .bin firmware on internet), and i dont know how to "compile arduino" github latest update.

Thanks for answer.

[YoImLee]

The black levels are wrong not because of GBS Control, but because of the chip used to convert the analog video to digital HDMI. My VGA to HDMI converter uses the very common MS9288A chip, which seems to also be used in the blue AliExpress unit. This converter washes out the picture on 960p and 480p resolutions.

If you were to use the VGA output with a compatible display you should get normal black levels.

[johngarcia000]

The black levels are wrong not because of GBS Control, but because of the chip used to convert the analog video to digital HDMI. My VGA to HDMI converter uses the very common MS9288A chip, which seems to also be used in the blue AliExpress unit. This converter washes out the picture on 960p and 480p resolutions.

If you were to use the VGA output with a compatible display you should get normal black levels.

Really? I use default HDMI out to HDMI on LCD Flat screen, how can i solve it?

That is my GBS: https://pt.aliexpress.com/item/1005005553175615.html?src=google&src=google&albch=shopping&acnt=768-202-3196&slnk=&plac=&mtctp=&albbt=Google_7_shopping&isSmbAutoCall=false&needSmbHouyi=false&albcp=17355674356&albag=&trgt=&crea=pt1005005553175615&netw=x&device=c&albpg=&albpd=pt1005005553175615&gad_source=1&gclid=CjwKCAiAmsurBhBvEiwA6e-WPOhJ_gigyDFCDhQdVBWw2JY0pvvlouwbx6QboZyWgy8qUJNXrRfNVRoCiGMQAvD_BwE&gclsrc=aw.ds&aff_fcid=2784fcb8c5ab438e95d8ebc8e78b22e1-1702064983098-04316-UneMJZVf&aff_fsk=UneMJZVf&aff_platform=aaf&sk=UneMJZVf&aff_trace_key=2784fcb8c5ab438e95d8ebc8e78b22e1-1702064983098-04316-UneMJZVf&terminal_id=2df5e9860c9f4d91a59c9eb97876217e&afSmartRedirect=y

[johngarcia000]

Update: I choose fullrgb on tv and lowered brightness direct on tv from 50 to 44, until gray image all around dessapear, and seems like it works this way. Image seems properly right now. when try lowering it direct on color corretion (brighness option) on wifi menu, it just become dark and Still crushing black. Is there another way instead lowering brightness direct on tv?

[YoImLee]

Changing the brightness on the GBS itself won't help because the output feeds into the analog to digital HDMI chip, which will mess with the black level regardless. Your best bet is to either use 1080p or adjust the brightness on the tv.

Another thing that works for me is using 720p and squishing the image to 4:3 using the scaling controls, then using the border controls to hide the overscan on the sides. 720p should provide a nice 3x upscale on your 4k tv and shouldn't have the black level issue. It may or may not look good, but it's worth a try.

[johngarcia000]

![Uploading 20231209_120307.jpg…]()

Changing the brightness on the GBS itself won't help because the output feeds into the analog to digital HDMI chip, which will mess with the black level regardless. Your best bet is to either use 1080p or adjust the brightness on the tv.

Another thing that works for me is using 720p and squishing the image to 4:3 using the scaling controls, then using the border controls to hide the overscan on the sides. 720p should provide a nice 3x upscale on your 4k tv and shouldn't have the black level issue. It may or may not look good, but it's worth a try.

Even 720p does the same black issue, and even adjusting borders or lowering brightness direct on tv still a bit washed (grayed inside video area) Any Resolution, some does more, some does less problems. Playing this way with black levels wrong is not a good deal to me. Maybe a good cable VGA TO HDMI could solve this?

[johngarcia000]

No answers??? I uploaded some pictures about problem. I tryed vga tô hdmi adaptar but the same isssue happen.

![Uploading 20231216_124911.jpg…]()

[invaderlex]

I know that many people are used to to watch TV with all the brightness to the max or at a very high level. There are some games on the 5th and 6th gen (ps1, ps2) with a calibration screen for that reason, Metal Gear Solid and Metal gear solid 2 comes to mind. You are not suppose to see what's in every dark corner on every game. You will need to learn how to watch TV at a proper brightness level. That same effect you describe happens on my DIY GBS using the recommended VGA to HDMI converter if the brightness is too high. I just reduced the levels until the gray square is barely visible, using the MGS calibration screen I can even go lower so is probably you playing with a brightness setting to play DOOM64.

[johngarcia000]

I don think that's its exaclty my problem my brother.

Em ter., 19 de dez. de 2023 às 16:23, invaderlex @.***> escreveu:

I know that many people are used to to watch TV with all the brightness to the max or at a very high level. There are some games on the 5th and 6th gen (ps1, ps2) with a calibration screen for that reason, Metal Gear Solid and Metal gear solid 2 comes to mind. You are not suppose to see what's in every dark corner on every game. You will need to learn how to watch TV at a proper brightness level. That same effect you describe happens on my DIY GBS using the recommended VGA to HDMI converter if the brightness is too high. I just reduced the levels until the gray square is barely visible, using the MGS calibration screen I can even go lower so is probably you playing with a brightness setting to play DOOM64.

— Reply to this email directly, view it on GitHub https://github.com/ramapcsx2/gbs-control/issues/516#issuecomment-1863349494, or unsubscribe https://github.com/notifications/unsubscribe-auth/BEIIM63ONRMHMYDN5KMYT2DYKHSTXAVCNFSM6AAAAABAK247KKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNRTGM2DSNBZGQ . You are receiving this because you authored the thread.Message ID: @.***>

[invaderlex]

I don think that's its exaclty my problem my brother. Em ter., 19 de dez. de 2023 às 16:23, invaderlex @.> escreveu: … I know that many people are used to to watch TV with all the brightness to the max or at a very high level. There are some games on the 5th and 6th gen (ps1, ps2) with a calibration screen for that reason, Metal Gear Solid and Metal gear solid 2 comes to mind. You are not suppose to see what's in every dark corner on every game. You will need to learn how to watch TV at a proper brightness level. That same effect you describe happens on my DIY GBS using the recommended VGA to HDMI converter if the brightness is too high. I just reduced the levels until the gray square is barely visible, using the MGS calibration screen I can even go lower so is probably you playing with a brightness setting to play DOOM64. — Reply to this email directly, view it on GitHub <#516 (comment)>, or unsubscribe https://github.com/notifications/unsubscribe-auth/BEIIM63ONRMHMYDN5KMYT2DYKHSTXAVCNFSM6AAAAABAK247KKVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMYTQNRTGM2DSNBZGQ . You are receiving this because you authored the thread.Message ID: @.>

Try not to use the internal HDMI out. use the VGA out with another converter to see if there is a problem there. Those Chinese companies will use the cheapest of the bunch just to get an image.

[naxeras]

What vga to HDMI converter is needed for solve the black crush image?

Regards.

[invaderlex]

What vga to HDMI converter is needed for solve the black crush image?

Regards.

[tmarques]

I have been doing a bit of reading on the standards and there seems to be both variations on black levels and some difference in the color spaces between PAL, NTSC and implementations. VGA is expected to be sRGB, which matches HDTV color space (Rec 709), so the color space would be the same.

Now there are some issues with regards to CRT TVs from that time. IIRC, PAL expected the hardware to do phosphor corrections but NTSC I think had some further correction to the signal. Colorspaces are different:

• Both have D65 white point, same as sRGB/rec709, so white will always look ok.
• PAL has a difference in the green primary but B e R match,
• NTSC instead follows SMPTE C which has differences in all primaries.

Then we have observable, reproduceable differences in saturation of composite signal on a CRT, which leads to cleaner signals displaying much more saturated colors than seems intended by the artists. The Genesis is one where it is very noticeable and I usually prefer to put scanlines on just to tame the excessive brightness and saturation.

But, to your point, there is also the black levels. Renesas has a document that goes over the standards and it says that within both PAL and NTSC the versions differ on black levels used:

NTSC-M and 4.43 have a black level of 7.5 (whatever that means) while J is 0. PAL is at 0, except for PAL-M which is also at 7.5.

As has been pointed out, some of this may be down to the combination of adapter (HDMI expects limited but Full is supported) and LCD monitor/TV. I have seen TVs that don't care what you send them, monitors that only take Full and most devices want to send "Limited" to HDMI and "Full" by DVI. So an DVI -> HDMI converter on the same device will produce different results as HDMI cable because the format is set by the output type. (On Intel laptops one has to force Full output).

Either way, this is only for RGB. If your HDMI adapter converts the output to YCbCr somehow, it will always match. I guess you can hook it up to a monitor or use some modded console to see if toggling NTSC to PAL fixes the black level issues.

Color should always look off unless we can understand and do some conversion on profiles (it did have knobs to start with!).