TV sizes

[Cameraken]

Hi Racc.

Thank you that’s really interesting.
I guess the IRE brightness will apply to PAL in the same way.

Do you have any info on PAL?
When I did some of these I stretched the pictures from 702 x 540 to 720 x 540
I can’t remember where I got the figure of 702. Do you know if that’s correct?

Ken.

[Racc Iria]

Sorry, I just saw this part.

From 1STLITE...
Also, when you open a new document there are guides included. WHat exactly are they for? I have noticed they are the same guides in my dvd program for making these slideshows, but I honestly have no idea what they are for. Which guides to I go by to be sure the whole image shows up?

I have been having issues with the whole image not showing up on the tv, so I really want to get this down before I mess another one up - lol. Oh and for viewing on a tv, do I use 72 ppi?

On a TV screen you can't see all the way to the edges of the picture... the bezel of the TV case as well as differences in pictures tubes which change as they age, etc. prevent this. This is refered to as "Overscan." The edges of a TV frame are really quite messy, and can contain ugly little bits of information like timecode blips, or in the case of DV video thin black lines down the left and right sides. So you really don't want to see the edges.

So, if you don't know where the edges are how can you make sure that important stuff will be visible on the screen? That's what those guides are for. The outside guide represents the Action Safe area and the Indise guide represents the Title Safe area.

Inside the Title Safe area is where you want to put any text or important elements that you want to guarantee will be seen when viewed on a TV screen. If the size of your image represents 100% of the screen, the Title Safe area is at 80% of your image size.

The Action Safe area represents 90% of the image size and is generally used to make sure action or movement in the image is visible, but it isn't as critical as text for example so it's get's a little more latitude.

Think of it this way... Anything inside of the Title Safe area is absolutely guaranteed to be seen on the TV screen. The closer you put stuff to the Action Safe line or the edge of the image the greater the chance it could be cropped off by the TV. Some really bad or old televisions sometimes overscan past the action safe line. So, basically the closer to the edge you put something the more you're gambling that it won't be seen.

Regular 4:3 standard definition television resolution is about 72ppi. If you have a 300 ppi image that you want to display on TV you don't have to change the resolution it'll show up fine, just like on a computer monitor. However, if you're creating images from scratch, making them at anything greater than 72 ppi is just wasting file size.

I apologize for missing those questions before.

--Racc

[Racc Iria]

From Cameraken...

I guess the IRE brightness will apply to PAL in the same way.

Do you have any info on PAL?
When I did some of these I stretched the pictures from 702 x 540 to 720 x 540
I can’t remember where I got the figure of 702. Do you know if that’s correct?

Hi, Ken.

Yes, most of what I talked about will work for PAL, too. The only differences are the image size and that PAL is much more forgiving with the colors. By following the guildlines for NTSC, but using the PAL image sizes you should be okay.

The PAL DV (non-square pixel) image size is 720x576. To make images for PAL using square pixels, make the image 768x576 and when you're finished, resize it to 720x576. PAL requires horizontal compensation, while NTSC requires vertical compensation.

I'm in the U.S. and so only work in NTSC, so I'm afraid I don't know as much about PAL, especially concerning the differences in color. I do know that one of the reasons PAL was created was to correct the color issues of NTSC. I'd have to do some research to learn more about it begfore recommending PAL safe colors. NTSC colors, though, are PAL safe since NTSC has a smaller color space.

Hope that helps.

--Scott

[Cameraken]

Yes. It does help.
Thanks Racc.

Ken.

[Kraellin]

racc,

interesting.

ok, here's a newbie question for you. what about the newer higher resolution tvs? are these using the same aspect ratios in general or something else? and are they using the same raster techniques as before only with more rasters or are they doing something else?

also, on a related question, what does s-video do, like if you hook up your computer to your tv via s-video? if the aspect ratios are different and the pixels are different, then how is s-video handling all this?

craig

[Racc Iria]

You're welcome, Ken.

From Kraellin...
what about the newer higher resolution tvs? are these using the same aspect ratios in general or something else? and are they using the same raster techniques as before only with more rasters or are they doing something else?

also, on a related question, what does s-video do, like if you hook up your computer to your tv via s-video? if the aspect ratios are different and the pixels are different, then how is s-video handling all this?

The newer TV's are a whole different ballgame. At this point, the color issues are still pretty much the same, but everything else is tossed on its head. The easiest way to tackle it is to decide beforehand what you need to design to. Standard Def, Letterbox, HD, 4:3, 16:9, etc. The rule of thumb is to design to the largest size/resolution you need and scale down from there.

The image dimensions and aspect ratio are largely determined by the television standard you choose. If you look in the stores, many of the HD 16:9 TVs have different maximum image sizes. Some are 720 vertical, some are 1080, and others have odd sizes. Most of this confusion is due to the HD standards war. Standard def is 480i. But now comes along 480p, 720p, 1080i, and now 1080p.

But, generally, for 16:9 image aspect ratios the width in Pixels for HD should be 1280 and Standard Definition 940 pixels. The vertical is determined by the standard. If using 480p or 480i, then the vertcal size should be 480 pixels. If you're using 720p, then 720 pixels, and 1080i or 1080p should be 1080 pixels. The most common flavor of HD in the U.S. at the moment is 1080i.

It can all be quite confusing. And this is also why DVDs are generally made two ways... 16:9 or letterboxed and 4:3 full screen.


Now, on to your easier question about S-video.

The NTSC standards are the same regardless of which type of connector you use. The difference between Composite, S-Video, and Component are basically a function of bandwidth.

A Composite signal (like that found using a single RCA connector) crams all the color information (chrominance), the brightness information (luminance), and timing information onto a single pair of copper wires (a positive and a ground). With all this info crammed in there, there isn't a lot of room, so the colors bleed and the signals interfere with each other making for a pretty noisy picture.

S-Video (also sometimes called S-VHS as it evolved from those days on VCRs) improves the picture by separating the chominance and luminance and sending each on a different set of wires, thus allowing more bandwidth for each resulting in a cleaner, better picture.

Component goes a step further and sends the signals for Red, Green, and Blue on separate wires vastly improving the bandwidth for each color resulting in a much clearer picture.

When you hook up your computer to your TV using an S-Video connector (or any other analog connector for that matter) the graphics card is basically performing the function of a scan converter, though usually not as well as a dedicated device.

If you're using a graphics card designed for video editing that has S-Video out to a monitor, it's probably not scan-converting your computer screen, but sending out the video signal from the editing application in which everything we've covered in this thread will have been taken into account, either by you or by the editing application.

If you're sending out the signal over a firewire card, then you're using DV and need a device like a DV tape deck, or a DV camera to convert the fireware DV signal back into video.

--Racc

[Kraellin]

racc,

thank you! a most excellent explanation of a somewhat confusing subject.

craig

[1STLITE]

THank you so much Racc. This is exactly what I needed to know. Thank you for being so very helpful!

Dawn

[Racc Iria]

It was my pleasure, guys.

In this world of converging technologies this kind of information is going to become more and more important not to mention confusing. Perhaps it will get better once standards have been decided.

Probably not, though.

Like I said at the beginning of this thread, I do this for a living. Making graphics for television/video, that is. So don't hesitate to ask if you have any video or TV related questions.

If I don't know the answer, I know a bunch of other people who probably do.


--Racc