Iowa Public Television

Monday, December 28, 2009

What's Wrong With This Picture?

One of the questions that I get most frequently is what's wrong with the picture. It seldom relates to the quality of the picture but the content of the picture. Why are the titles cut off? Why a titles in the middle of the screen rather than at the edge of the picture like they used to be? The issue is aspect ratio which is the relationship between the height and width of the picture. This is an important concept to grasp because in the transition from analog television to digital television, the aspect ratio changed. Traditional analog television has an aspect ratio of 4x3 which means that the picture is 33% wider than it is tall. Digital television's have an aspect ratio of 16x9 which means that the picture is about 78% wider than it is tall. This represents a pretty significant difference in aspect ratio. In my office I have an analog television with a screen that is 16 inches wide and 12 inches all. If you do a little basic math that confirms that the screen is 33% wider than it is tall. I also have a digital television in my office with a screen that is about 22.5 inches wide and about 12.7 inches tall. The same basic math will show that the screen is about 78% wider than it is tall.

If you think about it in terms of pictures and the frames we mount them in, it is a little easier to understand. Thanks to some friends at NBC, I'll use a picture that many of us are familiar with. Here is Da Vinci's Last Supper. Don't focus on the poor image quality but on the shape and the size relationship of the picture height to picture width. That is the aspect ratio. This particular image has an aspect ratio that is very close to the 16x9 digital aspect ratio. If you were to frame this picture for display you would measure the height and width of the canvas and then build the frame to those specifications. But what if you had to make it fit in a frame that you already have? This is the issue that many people are dealing with now as they try to display digital content on their old analog televisions.

If the desire is to show the complete 16x9 image in the existing 4x3 television frame, there are only two options. The first is to do what is called letterboxing the image. What this means isthat we scale or adjust the width of the 16x9 picture to fill the width of the 4x3 frame. The side effect of this scaling is that there is a portion of the 4x3 frame that the picture does not fill. In essence a black matte is generated to fill from the top and bottom edges of the picture to the top and bottom edges of the frame. As you can see from the example the entire 16x9 picture is displayed with the proper width to height relationship and is made to fit within the 4x3 frame. Image integrity is maintained but the actual image on the screen is smaller than a 4x3 picture would be.

The other option for displaying a 16x9 image on a 4x3 display is to forget about maintaining image integrity. in this case we would scale the width of the image to fill the width of the 4x3 frame and then independently scale the height of the image to fill the 4x3 frame. As you can see from the example, the 16x9 image fills the 4x3 screen but the picture is distorted. The characters are vertically stretched so that they appear taller and skinnier than normal. Conversely, if you look at the horizontal table, it appears to be shorter and than normal. So the 4x3 screen is filled but the picture content is compromised.

As I said, there are really only two ways to display the entire 16x9 image on a 4x3 screen. There are however other options that can be used. One popular one is called cropping or center cutting. If you have every taken a picture that is too large for a frame and trimmed it to fit, you have cropped. In television, because most of the important visual information is in the center of the screen, a 4x3 image is cut from the center of the 16x9 picture. Once again, the 4x3 screen is filled but the image is compromised. In the example image, although the characters in the original image maintain their proper width to height relationship, three of the original characters are no longer displayed so in this case we would see Jesus and the nine apostles. I am certain that Leonardo Da Vinci would not believe that this was an accurate interpretation of his work or an accurate representation of the historical event he is recording.

One technique that is often suggested is what is called center or 4x3 protect. What this means is that when the picture is being created, the action should be framed to all take place within the 4x3 center of the 16x9 frame. In some cases this is being done with some success but it is not always possible. In the example picture, this is what the Last Supper might have looked like if Da Vinci had created on a 16x9 canvas for display in both a 16x9 and 4x3 frames. As you can, all of the characters are in the image and their width to height ratio is proper but the image is unbalanced because of the compression of all of the action to the center of the frame while the left and right edges are more vacant and unused. In this case the image would look unusual on both displays.

It is challenging and sometimes impossible to create content that makes full use of the wider digital aspect ratio while trying to insure the content's integrity on legacy displays. Realizing that 4x3 displays are the legacy device and will eventually be gone and 16x9 or wider displays will be the norm, content needs to be created to take advantage of the benefits of new display technologies. For display on legacy devices, the first choice should be to maintain the integrity of the wide screen images through letterboxing.

Monday, June 15, 2009

Welcome all-digital TV!

Last Friday, IPTV officially became an all-digital television network! We spent Friday and the weekend taking calls from viewers who needed help, as we've been doing for more than 18 months.

If you know of someone who is still having trouble receiving Iowa Public Television, or someone who needs help, tell them to call IPTV at 1-800-532-1290. We'd be happy to help them.

Meanwhile, enjoy IPTV, IPTV LEARNS, and IPTV WORLD. Thanks!

Monday, February 9, 2009

Why is IPTV continuing analog broadcasting past Feb. 17?

We've heard from viewers concerned about our decision to continue broadcasting analog signals past the original Feb. 17 shutoff date following the national delay approved by Congress. We've also heard from viewers grateful for a little more time to get ready.

Iowa Public Television is, at our core, a public service media organization. We believe it's important to serve all Iowans, regardless of where they live or what they can afford to pay. And in the past year, we've fulfilled some of that public service role by assisting Iowans with questions and problems converting to digital television. We've conducted more than 100 town hall meetings around the state, aired 30 hours of information about the switch, and talked with thousands of Iowans having difficulty making the transition.

Though we did not advocate for the delay, we do see it as our role to take advantage of the extra time to provide information and assistance to those Iowans who aren't yet ready.

We have no doubt Iowans are aware of the switch - and we're not staying analog to help procrastinators. We believe, through our conversations and visits with Iowans, that most of those who haven't made the switch are having unanticipated difficulties with reception and antenna issues. Still others applied for converter box coupons and are now on a waiting list, or never received coupons to begin with.

There will be utility costs associated with staying analog for a few more months, and in these budget times taking on those costs was a difficult decision. We're finding other ways to save in these demanding budget times, because we strongly feel these costs are an investment in helping as many Iowans as possible be prepared for the switch. And of course, the individual contributions made by members will continue to go directly toward programming.

Iowans rely on television, not just for entertainment and a connection to the outside world, but for important public safety information. And Iowa's families - particularly those families in lower income situations without access to pay television or new televisions - rely on our service for safe, educational children's programs.

So though staying analog does incorporate additional expense, we feel the cost allows us to do the important public service mission with which we are charged - helping all Iowans through public media. It's why we were created, why we are supported, and it's our unique responsibility.

Thursday, February 5, 2009

What about that DTV delay?

By now you've heard about the national delay in the required analog TV shutoff date - the date is now June 12, 2009.

Iowa Public Television will continue to broadcast in analog until the new shutoff date. Though there is additional expense for Iowa Public Television to do so, we want to ensure as many Iowans as possible are able to make the switch.

We're finding that many viewers who contact us are aware of the transition, and have taken steps to be ready. But when they try to make the switch in their homes, many are finding they have reception and antenna issues. So, we're glad to take advantage of this extra time to help viewers on the phone, on the air, and online.

If you're ready, you can watch IPTV's three digital channels right now! And be sure to help your neighbors, family, and friends with their switch.

If you aren't ready, there's no need to wait. Give us a call at (800) 532-1290 and we can help you make the switch in your home.

We're committed to making sure as many people as possible are ready for the analog shutoff.

Friday, January 9, 2009

2009 Consumer Electronics Show - Day 1

I am attending the 2009 Consumer Electronics Show in Las Vegas and I am looking at a few very specific items. As I have been doing DTV information sessions throughout the state of Iowa, I have had an opportunity to listen to and answer many questions. However there are many more questions that still need to be answered and I have used those issues to determine what I am looking at.

Primarily there are four specific issues. First is recording over-the-air digital television. Many peopl who have purchased converter boxes have discovered that they make using existing VCR's very difficult. I am looking at what items are available to replace the analog VCR. The second area is indoor antennas. Although I am not a fan of indoor antennas because of the problems associated with indoor reception it is clear that many people want to continue to use them. I will be reporting on what is happpening on this front.

The third issue is about what is happening in display development. There are some exciting new technologies being unveiled at this year's conference. Many people are looking at new televisions and want to be sure that what they are purchasing is the right choice for them.

The fourth issue is audio. You don't have to watch too much digital television to recognize that there are some unresolved audio concerns. Audio/video synchronization is an issue and a number of vendors are offering the consumer some options for correcting these problems. And if you change channels you'll notice the other issue which is loudness or more precisely the inconsistent audio levels between channels. I will be reporting on what is happening on this front as well.

I will be filing my first report later today.