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Why do you need DR: a closer look at dynamic range Part 3

HDR displays, file formats and editing software are becoming more common. This video is designed to be played back on an HDR display.

In Parts One and Two, we discussed what dynamic range is and why dynamic range numbers only tell you a part of the story.

It’s also worth noting that JPEG files don’t even use a camera’s full dynamic range; they typically include only nine or so stops of DR. So, if dynamic range numbers don’t tell you much about a camera’s image quality, and your JPEGs only use a portion of it anyway, why do we try to examine cameras’ dynamic range, and of what use is it?

Which HDR: wide DR display or just wide scene DR?

Unhelpfully, the term ‘High Dynamic Range’ can refer to two things: tone-mapped photos that try to convey a wide DR scene on an SDR display, which develop a rather ‘distinctive’ look if there’s an attempt to include too wide a dynamic range, or wide DR images shot for playback on HDR displays, which can present this wider dynamic range in a more realistic, life-like manner.

When you’ve hit the JPEG limit

The most obvious case when you want more dynamic range is when you’re trying to photograph a scene that has more than ~9EV of dynamic range. The standard JPEG tone curve is designed to work for most photos, but sometimes you want to capture something like a sunrise or sunset that has more tones than the JPEG handles, and either the highlight detail clips or the shadow detail disappears to near black.

This is a good argument for shooting Raw, which gives you the option to reduce the exposure and brighten the shadows of your files to cope with dramatic lighting. In these circumstances, a camera with wider dynamic range will provide more usable latitude, especially in the shadows.

But the era of the ~9EV JPEG could be coming to an end.

Displaying wide DR images

The latest HDR displays can show a wider range of tones than conventional ‘standard dynamic range’ (SDR) monitors and TVs. They provide an opportunity to represent scenes with brighter highlights and less clogged-up shadows in a more naturalistic manner, meaning they can show dramatic sunrises and sunsets, or sunshine glowing through the petals of a flower, without the strange, circus-like look that exaggerated ‘HDR’ imagery can show. As HDR displays, 10-bit file formats that make the most of them and editing software that understands them become more commonplace, the ability of a camera to capture a wider dynamic range may become increasingly valuable.

Overall, then, while one shouldn’t use DR numbers as a catch-all summary of a camera’s performance, dynamic range itself remains an important part of image capture technology, and one that looks to become even more useful in the near future.

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