The significance of NTSC setup level (IRE)

[Xan]

I noticed that on my BVM I would get a darker than normal image when this is set to 7.5 IRE. On 0 IRE the image looks normal. Interestingly this is with PAL60, so I would think that the color would be encoded in PAL anyway. The signal also gets detected as PAL by the monitor. Either I didn't get something right or this setting is indeed not NTSC specific as listed.

IIRC when I used the PSX with S-Video a while ago it was set to 7.5 IRE, yet the image was normal. So far it seems that it either only affects Nintendo consoles, or something would be wrong with 0 IRE with the PSX.

Any thoughts?

[Ed Oscuro]

To my understanding IRE is more for picture uniformity, but yes, it does set up brightness. Of course brightness changes depending on the ambient lighting and preferences of the user - and there doesn't appear to have been any agreement among manufacturers about the "right" settings for brightness, either.

So back to the PlayStation - a couple questions. One, what's the model number on the bottom; two, do you know if it ever has been modified? That might answer the weirdness of the PAL setting, but that simply might not matter.

The piece of info that seems most critical to mention is that different machines simply output different voltages, or different brightness levels, when viewed on the same equipment. Also, some cables have capacitors built-in to drop the line voltage to a lower level. It seems strange if the PSX is significantly below a wide range of other consoles, but you might be able to notice variation if you compare other consoles, say early Sega and Nintendo systems.

There is a lot of information you haven't mentioned. How is the PSX connected? What were the "Nintendo consoles" and how were they connected?

[Xan]

Hmm, as I understood it, 0 is supposed to be specifically for NTSC-J, while 7.5 is for regular NTSC.

The PSX is a SCPH-7502, with modchip. It was hooked up with this cable. For Nintendo consoles, I tested a N64, GC and Wii, all PAL with regular composite cables and all had this dark image until I switched the setting. For RGB the setting doesn't matter.

[Xan]

I did some more testing now. To clarify, on 288p/576i the setting is ignored, on PAL60 480i and NTSC it gets applied. To me the brighter image with 0 looks correct on all instances so far. Here are the samples (PSX NTSC pics only, equivalent results with GC PAL60):

http://i44.tinypic.com/330z5hv.jpg (7.5)
http://i40.tinypic.com/veveoh.jpg (0)

It should also be mentioned that this particular cable gives visible moire in interlaced images via S-Video which is quite annoying. Oh well, I use RGB anyway...

[Ed Oscuro]

Thanks for the test shots, but photographs can't really be meaningfully analyzed for detail if there's any possibility the blooming is due to the camera's settings and not the television. Those shots look well done technically though, rather impressive as many people have lots of trouble with taking simple pictures and the CRT complicates that a great deal.

[Xan]

The shots aren't great, but it's about the best I can do with a cellphone camera. Although I now see that tinypic lives up to its name and resizes them from 8 megapixels to 2, so maybe I'll reupload them elsewhere later.

[Ed Oscuro]

Well, if the cellphone doesn't have any facility for locking the exposure to something consistent between shots then it's obviously not useful for us to try to gauge anything about it here. Don't feel like you have to do that, because we really can't learn much from it. (Except maybe that sometimes people with cellphone cameras do better than people with expensive DSLRs!)