Safe Color Range for TV

[Bob]

I shouldn't post anything that requires thought, critical or otherwise, late at night

There is, of course, a checkbox in the convert to profile dialog box to flatten the image. It's checked by default. If you uncheck that, you will get a warning message that the appearance of layers may change and give you the option of merging or not. If you don't merge, you will preserve your layers.

I didn't answer your question about sdtv ntsc 16-235 either.

If you do a convert to sdtv ntsc and the image contains pure black and pure white areas, after conversion those areas are still pure black (0) and pure white (255). If you do a conversion to sdtv 16-235, those areas will be 16 and 235. The conversion to sdtv ntsc 16-235 only addresses luminosity so it won't necessarily bring other colors into the sdtv ntsc gamut. I say won't necessarily, because the clamping to 16 and 235 occurs per channel in the conversion, this will affect colors that have a value outside that range. But, that's a side effect. There is a subtle difference between the conversion to sdtv ntsc 16-235 and the use of the levels adjustment layer with output levels restricted to 16-235. The way we (and the action) construct the levels adjustment layer, we are clamping the composite RGB, not the individual channels. The composite RGB is a weighted value so the results will not be the same as clamping the individual R G B channels. That's probably not a big deal. But, be aware of it. If you are going to use the convert to sdtv ntsc profile to force the colors into gamut, I'd do that first, then do the safe colors conversion.

Chroma, as I used it, referred to the hue and saturation values. When you are manually correcting a color to bring it into gamut, you target the color by whatever method makes sense in your specific case (by layer if you have separate layers for each color, or by selection or masking etc.). The point is that you isolate the specific color or color range. Then, you adjust the hue, or saturation, or both -- whatever makes the most sense in your situation.

[Stregga]

Ok Bob,

This is getting the best of me. So I read everything you said and a lot of it made sense to me. I did a couple of samples to see some of the things you were talking about which has led me to this question.

Does PE4 handle color differently for the DVD Menu layers? For example I have a full 255 white for a frame on the menu and it comes up PERFECT on my standard TV, but when I use the 255 on a (=1) Highlight layer it doesn't show at all and when I try to lower the luminosity to somewhare between 230 or lower it appears to take on the characteristics of the color behind it. Or in other words I see the shape of the highlight but just barely since it looks the same as the color behind it. Kind of like a transparancy.

I am telling you this has been so frustrating for me because when I make the adjustment and look at the on PE the work great, but when I burn it to a DVD and play it on the TV it doesn't show, and it is only happening with the Highlight layer not the other parts of the menu. The gamut and other suggestions you provided resolved all the other issues, but this one continue to linger and it is quite annoying.

So does PE handle the color differently for the highlight layer than any other layer?

[Steve Grisetti]

I too have had trouble with certain colors not showing as highlights, Marcos.

Since then I've made a point of using only web safe colors for highlightts and I haven't had a problem.

(Although that doesn't explain pure white -- which is web safe, but still doesn't show up on a DVD menu. Hmmm.)

[Stregga]

Well I am glad that I'm not the only one Steve. So as to make sure that I am not confusing what you said Steve, you use the web safe colors Only for the highlight layer and Not for the other layers.

If that's what yo have found to work, then I will just make that a practice.

Thanks for your reply Steve.

[Steve Grisetti]

Yep. Only the highlights have given me trouble.

[Stregga]

Thanks Steve,

I will use Web Safe colors for my highlights as a practice from now on.

If you can do me a favor, would you please let me know if you ever figure out anything different with this or why the difference? I am just a curious cat and like to know why stuff works or doesn't work.

Thanks Steve.

[Bob]

I think you may have stumbled on another gotcha. Unlike the other image elements, the Highlight layer is dynamically used by the DVD player to display the selection and you are subject to the DVD player limitations as to supported colors. I recall reading somewhere that the number of colors that a DVD player uses is limited. I think there was a minor reference to that in the Prel2.0 DVD Template Guide. I haven't seen any documentation as to what are "hightlight safe" colors though. If the DVD player uses 8 bit color, it would approximate the web safe palette (web safe includes 216 of the possible 256 values). That could explain why Steve has had better luck with web safe colors. As to pure white, that's not an NTSC safe color. It's possible that the DVD player excludes it from the highlight palette.

[Steve Grisetti]

Thanks, Bob.

After researching some of Adobe's help documents, I can only say for sure what Adobe says: That the engine that generates the background of a DVD is not the same as that used to generate the DVD menu highlights. So there is clearly a "highlight safe" range -- but I've yet to figure out exactly why or what it means.

Although I did find this interesting note: "On an RGB scale, white is 235 and black is 16. When picking colors for use onscreen, don’t exceed this color range for any of the RGB values. You can also add a Levels adjustment layer on the topmost layer and clamp output levels to 16 and 235."

Does that help?

I also found these words of warning: "Do not use gradients, feathering, or anti-aliasing."

I've done that, and the results have not been what I've expected. I'm sure it's related to that same narrow color range issue.

[Stregga]

Have I ever told you guys that you Rock!!!!?

Yes Steve it does help. Thanks again Bob.

Steve earlier in this post Bob and I discussed the issue I was having with some of the layer styles, and I had issues with gradients, feathering, and glows, but based on what you just said this makes some sense now. Limitations seems to be the big key here, and understanding the limitations of your equipment will minimize headaches.

So I guess my challange here is to see what the color range is for my DVD and TV. It's tough since I have a high def tv, but my bro. in law doesn't and I am making this DVD for him. So I am trying to get it to work with my SDTV.

Anyway, is there a way that you guys might know of that I could test that color range for my TV/DVD player so that I can avoid it this in the future?. Kind of like a color bar thing, if that makes any sense.

When picking colors for use onscreen, don’t exceed this color range for any of the RGB values. You can also add a Levels adjustment layer on the topmost layer and clamp output levels to 16 and 235."

Steve, I had a problem getting the DVD Menu to work when I added either a folder or a layer in the past, I can't remember. But from what you're saying I should be able to add that adjustment layer and have no issues. I did try this before when Bob suggested it, only that I did it for each layer I was having problems with and then merged it so as not to have any issues. Should this be doable without any problems?

[Steve Grisetti]

According to what I read about Encore, it is possible to have an adjustment layer in your DVD menu template.

But I tend to play closer to the vest, Marcos. So I usually keep it as simple as possible.

[Stregga]

Point Well taken Steve...Simple it is.

[Bob]

Simple is best!

I did a little research and found the way the highlight function works is documented in the DVD Specification. However, that is proprietary (you have to sign a non-disclosure and pay a substantial fee to get it). There is an unoffical dvd specification guide ebook that you can purchase for a modest fee, but I didn't feel like buying it. The available free information indicates that the colors you choose for the highlights are converted from RGB to the YCrCb (YUV) color space and stored in a small matrixed palette at 8 bits per channel which the DVD player uses to generate the dynamic highlight as you display or select a menu item. There is a limitation on the number of highlight colors (3) in a set. Aliasing, gradients, dithering, etc. are bad because they generate more than 3 colors with the result being unpredictible palette contents.

I suspect that using web safe colors for highlights is probably a good idea. Web safe colors already can be represented in 8 bit per channel so you'll have a better chance that they will convert well. There is still the possibility that conversion from 8 bit RGB to 8 bit YCrCb will result in a change in color. So, it's best to preview. While it would be best to actually burn a DVD and play it on a representative target DVD Player, I suspect that burning to a folder and viewing with a software DVD player will give you a pretty good idea whether it's going to ok or not.

Restricting the output range to 16-253 (NTSC broadcast safe) is still a good idea.

[RJ Johnston]

If you don't like the highlight colors you are given, you can try editing them with PGCEdit.

You need to "burn" your DVD to a folder. Then you open the VIDEO_TS folder from within PGCEdit. When you double click on titles and menus on the left hand side, another dialog opens -- PGC Editor -- with the 4x4 color palette along with the chapter and permission settings. You can import colors that you have exported from a different DVD, or modify them with the color dialog.

After saving that and finally saving the DVD, you burn the VIDEO_TS folder to a real DVD using Nero or Image Burn (ImgBurn) or something else.

If Adobe follows the CCIR 601 specifications, the color range is automatically limited to the 16-235 range.

[Stregga]

Bravo!

You guys never stop amazing me. I truly appreciate all your effort in helping me better undersatand how color works with PE and DVD players. I was loosing it there for a while thinking I had to be missing something, but you guys have cleared up quite a bit of my confusion. I can't say that I fully understand ever single detail, but I do undersatnd enough to resolve my current problem, and for that I thank you all.

RJ,

I have never played around with PGCEdit, it sounds like a pretty neat tool. Where can I get it and how hard is it to learn?

[RJ Johnston]

Here is a link for PGCEdit

http://download.videohelp.com/r0lZ/pgcedit/pgcedit.exe

You can search for "PGCEdit" in this forum and over at the Adobe forum and should find threads about using it. There is also lots of information on the author's website, which you can find by going to the PGCEdit Help menu after installing PGCEdit.