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Welcome to the personal web-site of Dez Iddon, a web-site developer / designer residing in Clonmel, Ireland. Come in, Stay a while, Stay Forever!!

18.12.2005 ~ Gaming / Hardware

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Fri, 03 Feb 2012 16:17:03

What the hell is High Dynamic Range?

HDR (High Dynamic Range) is the next leg up in computer gaming light effects. It takes the bright light 'blooming' effect from the Far Cry game engine and it applies it across the board. To quote graphics wiz Paul Debevec:

 "The 'dynamic range' of a scene is the contrast ratio between its brightest and darkest parts. A plate of evenly-lit mashed potatoes outside on a cloudy day is low-dynamic range. The interior of an ornate cathedral with light streaming in through its stained-glass windows is high dynamic range. In fact, any scene in which the light sources can be seen directly is high dynamic range."

Swell! So what does that mean for the average gamer? Is it not just another pretty effect that will be turned off to get a higher frame rate?

Enter Half-life 2 : Lost Coast

Valve have been beavering away over the past year to add HDR support to their source game engine, the public culmination being the release of a playable tech-demo called 'Lost Coast'. The level itself was cut from the original Half-life 2 (on time constraints I believe) puts you in the shoes of Gordan Freeman, as he treks up a cliff to a church overlooking a quaint sea-side village - which is being shelled by the Combine. Short but enjoyable!

The real treat are the visuals. With everything notched up and HDR enabled, the game becomes a joy to behold. Obvious tricks are used to introduce us to the new visual effects (a beautiful beach scene with light shimmering off the water and dancing on the wet rocks and the light pouring through the broken windows in the church). Less obvious, but in my opinion more spectacular are the tone-mapping effects.

Tone-Mapping

These effects concern themselves with emulating the iris in a realistic fashion, so if you've been fragging combine in the sun and take cover in an unlit corner to reload, you will find your refuge initially very dark, but as your virtual iris expands the corner becomes brighter. Vice-versa is also true, so if you emerge guns blazing into the sun, you will find the light over-whelming until your virtual iris contacts - it is a fantastic effect.

So where does the humble 9800XT come into play?

I have been of the mistaken belief that ATI's range only supported HDR from the x800 series up - how wrong was I? A quick gander at the video settings of Lost Coast revealed a little toggle to enable the various levels of HDR, with the HDR bloom effect defaulted. So I gave it a go with full HDR enabled and to my surprise it worked, and worked well, albeit with a notch back on the resolution! Cue: awkward looking happy dance!

Where do I get my fix? 

HDR has presently made an appearance in the following games:

Tags: computers, games.