In graphic detail

Creating graphics can be a challenge but that can be easily overcome
Analysis, Delivery & Transmission


Contending with a multi-format environment and various distribution platforms when creating graphics can be a challenge but one that can be easily overcome, says Pixel Power’s James Gilbert

Providing channels with a strong, instantly identifiable brand is vital in today’s highly competitive broadcast landscape. Broadcasters want and need viewers to able to identify with what they are watching from a brand perspective – and it is what makes a collection of programmes into a channel. In turn, this creates brand loyalty and, therefore, a far more attractive platform for advertising and/or subscription. In a world of crowded EPGs, the value of a brand cannot be overestimated.

Beyond this, there is the question of onscreen information provision to also increase stickiness – what is coming up next, starring who and so on. Using graphics in these ways is vital, be it in an SD, HD or mixed environment.

The move to HD for many across the Middle East has begun and is now beginning to gather momentum. As with other parts of the world, it is not clear which HD format will be settled on – indeed it may remain a multi-format HD world. From a graphics perspective, what should broadcasters look for in the move to HD and how much does the variation in formats affect the workflow?

The industry has to deal with multiple formats, regardless of HD, with the growth of wider content distribution via mobile and IPTV to various format devices and handling different varieties of HD is a subset of this wider issue. But manufactures can and are providing solutions.

Achieving superior picture quality is the foundation for implementing HD. However, HD graphics require around five times as many pixels as their SD counterparts, which means broadcasters must ensure they have five times (10 times for 1080p60) the storage capacity, bus bandwidth, rendering power and processing power within their facilities, and up to approximately five times the bandwidth and space segment for transmission.

All HD uses 16:9 and this has a significant impact on the graphics as the aspect ratio of actual graphics pixels also differs. On a standard computer screen, pixels are square. On SD TV, such as PAL and NTSC formats, they are not. In HD however, they are. This is a major consideration for creative technicians whose job it is to design and produce graphics. If a broadcaster wishes to produce HD or SD, this is not such an issue. If they wish to use both in the same facility with the same graphics, they must ensure they have the technological architecture and workflow to support this.

There are two principal ways of getting around this. The first is to design all graphics in the ‘SD-safe’ area in 16:9 (HD) aspect ratio. By restricting key elements of the graphic such as names and logos to the area that will appear in the 4:3 picture, the sides can simply be chopped when the HD graphic is down-converted to SD.

Alternatively, the reverse can be done. Designers can create their templates in 4:3 (SD) but build in a 16:9 ‘safe area’ for up-conversion to HD. This means that when the graphic is ‘letter-boxed’ (ie the top and bottom aspects are removed), the key element of the graphic remains visible.

Of course, the most efficient way to accomplish this is to use a character generator that converts graphics in either of the above ways automatically. In doing so, it changes the resolution, frame rate, picture aspect ratio and scanning rate of the graphic. However, this does not produce the best results.

A better way is to create separate templates for SD and HD graphics. An added bonus of the fact that HD graphics use more pixels is that they can be reduced in size and remain readable. Consider that a typical football score might appear 20 lines high in SD. In HD, it would be proportionally twice the size but could be reduced by around 25%. This method frees up screen real estate for either more main picture or further graphics from sponsors, which would add a revenue stream.

This doesn’t create more work provided the broadcaster has a character generator that simultaneously feeds metadata, such as names or scores, to both HD and SD templates. The broadcaster simply needs to create two templates instead of one.

The number sequences 625 and 25 fps for SD are now familiar to most broadcasters, as are 1080i60, 1080i50, 720p60, 1080sf48, 1080p24, 1080p25, 1080p50 and 1080p60 for HD scanning. Right now the perceived difference between 720p and 1080i formats is very marginal. A network or broadcaster chooses one or the other, the majority being 1080i. Many are talking about 1080p50/60 but the delivery channel and much origination equipment is not there right now.

Broadcasters must plan which formats they intend to use and ensure their character generators can accommodate them all. This is particularly important if, for example, a studio produces a drama in 1080p24 but transmits it in 1080i. The character generator must automatically adjust the graphics accordingly. Some formats suit different types of programme. For example, p24 cannot accommodate the rich visual features of fast-action pictures such as sport and tends to make the picture appear ‘jerky’. In this case i50 would be better. However, p24 remains sufficient for slower action subjects or situations with less camera movement such as studio-based magazine shows or news.

In the same way that specific hardware is required for HD graphic creation, the process of editing graphics also has technological needs. First, monitors must be bigger and/or higher resolution. To incorporate all pixels of the HD graphic clearly, plus toolbars and menus, the screen should ideally have more than 1920x1080 pixels. For editing, a dual-display is ideal for presenting the GUI so the character generator must be able to support this.

We see that there is very little that needs to change in terms of workflow in making the transition to HD graphics, or adding them alongside an existing SD output. The right technology mitigates risk and minimises practical changes. It also helps create graphics strategies that open potential new revenue streams. This, ultimately, is the aim of migrating to HD.

James Gilbert is joint MD of Pixel Power

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