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240p test suite
http://forums.nesdev.com/viewtopic.php?f=22&t=13394
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Author:  lidnariq [ Wed Jan 31, 2018 11:29 am ]
Post subject:  Re: 240p test suite

Shade $0D is unfortunately significantly darker than 0 IRE. The NES was designed for NTSC-J , so there was no design for different black and blanking levels.

This wiki page contains the measurements I did some years ago: color $0D is approximately -12IRE.

With full color emphasis on, shades $01-$0C average to approximately 4 IRE.

Author:  SpiderWaffle [ Thu Feb 01, 2018 1:25 pm ]
Post subject:  Re: 240p test suite

Even with -12 IRE, I'd still rather have that (and a light grey on the right bar) for some limited functionality, rather than zero functionally with everything the exact same color.

Also the grid on the linearity screen (pressing A) is BY FAR the best and most useful test pattern, (I believe it's 7x7 black pixel squares with 1 pixel thick lines, which are very good parameters) could be EVEN BETTER if pressing A again could cycle to remove the 5 circles, as these circles often get in the way, much like an OSM does when trying to scrutinize a white line for calibration.

Author:  dougeff [ Thu Feb 01, 2018 2:04 pm ]
Post subject:  Re: 240p test suite

You'd rather have this?

https://youtu.be/3fhyX3HdVcg

(the immortal uses color $0d for black here...)

Author:  SpiderWaffle [ Thu Feb 01, 2018 4:20 pm ]
Post subject:  Re: 240p test suite

"The game uses a non-standard "blacker than black" color value for black pixels and then further exacerbates the problem by using "emphasis bits" to darken the whole screen. This pushes things even further out of spec so that the TV sees a sync pulse where there shouldn't be one."

Well if that's the case no, but I assume that was with composite, and maybe RF only. I'd be interested in using it for RGBS which would have the sync line separated and couldn't happen. Further, I wonder how much the emphasis bits play a part in that vs -12 IRE instead of the 0 which every CRT is more than designed to handle.

Regardless, a light grey on the right bar would be better.

Author:  lidnariq [ Thu Feb 01, 2018 4:52 pm ]
Post subject:  Re: 240p test suite

If you're using RGBS from a NESRGB, HDNES, or 2C03, it's already completely synthetic and only vaguely related to the composite generated by the 2C02... I doubt any of those devices emit something useful for shade $0D.

The "SMTPE color bars" test does and "IRE" test can already display shade $0D.

Author:  SpiderWaffle [ Thu Feb 01, 2018 8:36 pm ]
Post subject:  Re: 240p test suite

"The "SMTPE color bars" test does and "IRE" test can already display shade $0D"

Are you saying they use $0D currently? O.o

Author:  lidnariq [ Thu Feb 01, 2018 9:01 pm ]
Post subject:  Re: 240p test suite

That is, in fact, exactly what I am saying.
Attachment:
240pee-NES-SMTPE-color-bars-with-shade-0D-indicated.png
240pee-NES-SMTPE-color-bars-with-shade-0D-indicated.png [ 304 Bytes | Viewed 340 times ]


Attachments:
240pee-NES-IRE-test-with-shade-0D-indicated.png
240pee-NES-IRE-test-with-shade-0D-indicated.png [ 196 Bytes | Viewed 340 times ]

Author:  rainwarrior [ Thu Feb 01, 2018 11:53 pm ]
Post subject:  Re: 240p test suite

From what I recall, the small deep-black region in this ROM's test is not nearly as problematic as with The Immortal. Sometimes how much of it there is onscreen can matter a lot. E.g. my capture card wobbles with The Immortal but didn't seem to be bothered with this test. Loss of picture is theoretically possible, but it really varies from hardware to hardware quite a bit.

Incidentally, this has actually been discussed twice in this thread previously:
https://forums.nesdev.com/viewtopic.php?p=159374#p159374
https://forums.nesdev.com/viewtopic.php?p=178503#p178503

Author:  SpiderWaffle [ Thu Feb 08, 2018 12:44 am ]
Post subject:  Re: 240p test suite

lidnariq, that's neat they're in there, (though the IRE pattern is somewhat dubious because also has much lower values); unfortunately, it doesn't seem to work at all like others have said, at least with RGBS and S-video through the RGBNES, could it maybe somewhat work through composite/RF unmodded?

I think a better idea, that could still include the marginal useful if any -12 IRE $0D, would be to use all of the NES darkest colors alternating with a black bar, so a pluge pattern like this:

| $0D | $0E | $08 | $0E | $09 | $0E | $00 |

which could be actually pretty useful, I know when turning down the brightness a bit too low you can't distinguish a black from that dark brown, like at the start of Castlevania 3 (dark brown hair on black background and later in level the whole big house background)

Author:  SpiderWaffle [ Thu Feb 08, 2018 12:58 am ]
Post subject:  Re: 240p test suite

Sorry for double post but this maybe got missed:

The grid on the linearity screen (pressing A again) is BY FAR the best and most useful test pattern. (I believe it's 7x7 black pixel squares with 1 pixel thick lines, which are very good, if not ideal parameters) It could be EVEN BETTER if pressing A again could cycle to remove the 5 circles, as these circles often get in the way, much like an OSM does when trying to scrutinize a white line for calibration, particularly convergence.
(If you wanted to get really fancy, a way to change between just horizontal lines or just vertical lines could be just slightly helpful)

The solid color screen is also awesome for checking purity.
Those two are about the only patterns I use 240p test suite for.
And I guess with higher end consoles, the SMTPE pattern can actually be accurate enough auto-calibrate BVMs and the like.

The sound check, system clock checks, lag test and some others are pretty neat too.

The "Grid" is so over used, the linearity's grid is so much better, grrr.

Author:  tepples [ Thu Feb 08, 2018 7:05 am ]
Post subject:  Re: 240p test suite

Thank you for the feature requests.

SpiderWaffle wrote:
I think a better idea, that could still include the marginal useful if any -12 IRE $0D, would be to use all of the NES darkest colors alternating with a black bar, so a pluge pattern like this:

| $0D | $0E | $08 | $0E | $09 | $0E | $00 |

So something like this I take it, where hot pink represents the $0D.
Attachment:
dark_color_bars_proposal.png
dark_color_bars_proposal.png [ 1.62 KiB | Viewed 181 times ]

How would that test be translated for the RGB consoles (TG16, Genesis, and Super NES)? Mostly I try to track the functionality of the Super NES test, and I might include a corresponding screen in the NES version. I'll pass on your request to the topic on Shmups Forum to see if they can come up with a corresponding test.

SpiderWaffle wrote:
[The Linearity test] could be EVEN BETTER if pressing A again could cycle to remove the 5 circles, as these circles often get in the way, much like an OSM does when trying to scrutinize a white line for calibration, particularly convergence.

The grid in Linearity is 7 pixels wide and 8 pixels tall on NTSC or 8 pixels wide and 11 pixels tall on PAL. This gives it as close as I can get to a square aspect ratio for the grid squares. But loading two images (circles only and circles with grid) takes up all of video memory on the board I'm using. In order to cycle among more than two screens (circles only, circles with grid, grid only, horizontal lines with same spacing as Linearity grid, and vertical lines with same spacing as Linearity grid), I'd need to load screens into video memory in response to a button press. I could do this one of two ways:

  1. Cut to a black screen
  2. Fit the updates into vertical blanking time, which incurs a lag of 40 frames (two-thirds of a second) to load the 5K of data that make up a screen at 128 bytes per frame

As I get time, I'll let Shmups Forum know about the limits of Grid and Linearity when setting convergence to see if there's demand for a fine grid test as you describe.

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