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 Post subject: Calibrating black levels on PVM
PostPosted: Sat May 23, 2020 11:07 pm 



Joined: 15 Oct 2017
Posts: 135
I'm having trouble trying to calibrate black levels on my PVM-20M4E. I'm calibrating to 0 IRE despite almost every online source saying to calibrate to 7.5 IRE. As far as I understand it, the latter's only relevant to NTSC (so, composite or S-Video) and RGB/YPbPr/PAL/NTSC-J should show clear differences between the three black bars at the bottom of the SMPTE test pattern (from the 240p test suite).

The problem is my PVM seems to start pushing blacks up once you start taking it below 7.5 IRE. With the settings I have now, I quite like how shadow detail looks but the blacks are practically LCD-esque at this point, clearly brighter than the wall in a dark room, and they're never that great with ambient light anyway. When you look closely, you can see the scan lines are brighter than the blank lines on a black screen.

Messing with the sub-brightness in the service menu didn't seem to do much, just raise/crush black levels in a similar way. It's a 20M4E so it's not *that* old and I'm pretty happy with everything else apart from some convergence issues with text in the edges/corners.

Any solutions? Am I calibrating to the wrong standard or could it be a hardware issue?

EDIT: I'm testing on a European Wii hooked up through composite.


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 Post subject: Re: Calibrating black levels on PVM
PostPosted: Sat May 23, 2020 11:30 pm 



Joined: 14 Aug 2017
Posts: 950
IRE 0/7.5 settings on your monitor will only apply when displaying CVBS or YC signals. Component (RGB, YPbPr) signals will not be affected by this setting, regardless of whether the source is marked as NTSC, NTSC-J, or PAL as its "region".

As a rule of thumb, IRE 0 was the standard used for NTSC-J signals in Japan, whereas IRE 7.5 was used for NTSC in North America. Not sure about PAL and SECAM (probably 0).

In theory, if for example you're playing Japanese content over composite or S-video, it may have been "mastered" for IRE 0 when using any of the two, but in practice which setting looks right for you will depend on how you have calibrated brightness and contrast for one or the other beforehand. You may have better results saving different calibration settings per channel.


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 Post subject: Re: Calibrating black levels on PVM
PostPosted: Sat May 23, 2020 11:45 pm 



Joined: 15 Oct 2017
Posts: 135
fernan1234 wrote:
IRE 0/7.5 settings on your monitor will only apply when displaying CVBS or YC signals. Component (RGB, YPbPr) signals will not be affected by this setting, regardless of whether the source is marked as NTSC, NTSC-J, or PAL as its "region".

As a rule of thumb, IRE 0 was the standard used for NTSC-J signals in Japan, whereas IRE 7.5 was used for NTSC in North America. Not sure about PAL and SECAM (probably 0).

In theory, if for example you're playing Japanese content over composite or S-video, it may have been "mastered" for IRE 0 when using any of the two, but in practice which setting looks right for you will depend on how you have calibrated brightness and contrast for one or the other beforehand. You may have better results saving different calibration settings per channel.

PAL is 0 IRE, yes.

I understand the region differences between 0/7.5 IRE (I think), my problem is after calibrating black levels to 0 IRE with the SMPTE and PLUGE test patterns on the 240p test suite (as I'm outputting PAL composite, and black levels would need to be calibrated with either of these test patterns over component signals anyway), blacks look... not very black. It's nothing to do with the IRE settings on the monitor, it's the brightness knob on the monitor and altering it so it's not crushing blacks below 7.5 IRE on the test patterns or raising 0 IRE to grey.

Basically, when I calibrate brightness to 7.5 IRE, blacks look good, but I (presumably) lose shadow detail. When I calibrate brightness to 0 IRE, blacks start looking more grey, but I retain the intended shadow detail. This is while using a European Wii connected over composite with PAL mode turned on in the 240p test suite.


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 Post subject: Re: Calibrating black levels on PVM
PostPosted: Sun May 24, 2020 9:56 am 



Joined: 20 Feb 2016
Posts: 314
I don't have a PVM but I have the same experience with a consumer Sony CRT. Basically because of gamma the brightness of the darkest black bars are so close together that the differences are not clearly seen.

If you raise the brightness so that there are clear differences you have raised the black levels higher up the gamma curve which will show black as grey.

I just keep black as black and I can see the 2nd or 3rd black bar in the grayramp just barely lit up if I look very closely.

Maybe you can adjust gamma on your PVM?


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 Post subject: Re: Calibrating black levels on PVM
PostPosted: Sun May 24, 2020 11:17 am 



Joined: 15 Oct 2017
Posts: 135
paulb_nl wrote:
I don't have a PVM but I have the same experience with a consumer Sony CRT. Basically because of gamma the brightness of the darkest black bars are so close together that the differences are not clearly seen.

If you raise the brightness so that there are clear differences you have raised the black levels higher up the gamma curve which will show black as grey.

I just keep black as black and I can see the 2nd or 3rd black bar in the grayramp just barely lit up if I look very closely.

Maybe you can adjust gamma on your PVM?

Yep, that’s pretty much the same problem I’m having. It’s frustrating considering, in theory, you’d be crushing blacks and shadow detail in every non-NTSC source. I remember having similar issues with my old consumer CRT(s) so I wonder if this is inherent to the technology or we just got unlucky.

I don’t remember seeing gamma in the service menu, so I’m not sure it can be adjusted.


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