The Advantages of DR400 vs DR200 vs DR100 - High Contrast Scene

Started Sep 2, 2013 | Discussions thread
David Rosser
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Re: The Advantages of DR400 vs DR200 vs DR100 - High Contrast Scene
In reply to Trevor G, Sep 10, 2013

Trevor G wrote:

Here are some comparison images showing the advantages of using DR400 at any time, or most of the time.

Fuji call this highlight headroom extension technique (among other things) EXR processing, which is not to be confused with EXR sensors in the smaller Fuji cams. It exists in the X10 and the X20, F series EXR cameras and so on. It is also used in the large, APS-C sensor X-Series cameras

In the X10, XS-1 and XF1 it is used in conjunction with the unique sensor pixel pairing EXR hardware system to give close to 2 to 3EV of highlight protection. In the X20 it is the sole means of getting extra highlight headroom.

In the previously mentioned EXR cameras EXR sensor pixel pairing works in M size and when ISO is less than DR.

In L size images only the EXR software processing is used - we know that because to invoke it you need to use at least ISO200 for DR200, and at least ISO400 for DR400. In M size you can get DR400 at ISO100 because the EXR hardware solution is at work.

Background:

DR200 and DR400 come in handy by extending highlight headroom to reduce the chance of clipping or crushing highlights in JPEG, but it's especially valuable in RAW.

It's a bit of a party trick - you can get the same highlight results by under-exposing by 1 or 2 stops and then lifting the resulting image in PP by 2EV or so. However, if you use DR200 or DR400 in-camera, the resulting JPEGs will have their lowlights lifted as a bonus.

The main benefit of DR higher than 100 (which means straight off the sensor processing, no tricks) is seen when you have a high contrast scene, or one where scene elements would exceed 0EV.

Enough talk, here are examples. This is a scene where highlights were 2EV above 0, or 2EV higher than where the metering produced a fully exposed image according to the playback histogram in processing software.

Unfortunately, because Fuji won't give us a proper in-camera RGB histogram, you cannot use the on-board histogram to do anything other than give you a very rough guide as to where exposure should be.

First, DR400 RAW:

Next the matching ooc JPEG - notice how the highlights are close to being blown and lack contrast because of the compression which occurs at the top end during JPEG processing. The lowlights have been lifted:

Next we see what happens with DR200:

If you look closely you will see that the clouds are just starting to clip in spots (bright white, loss of detail). Still, it's an amazing result for DR200 at 2EV higher than 0.

The ooc JPEG doesn't fare as well, but then again, it's not all that much worse than the DR400 effort.:

And finally, DR100. The RAW is badly clipped (it might look better in Adobe, I'll try that later, but it still won't be good).

In this case if we had exposed at -1EV on the dial the DR100 image would have been quite OK, even though the histogram was suggesting that at +0.7EV it was not clipping:

I'm only showing the DR100 JPEG for consistency:

Note the cyan skies in each JPEG, showing that they were all clipping one channel at least.

Of course, if I had exposed at -1EV even the DR100 image would have been fine, but that's not the point.

Most times with high contrast scenes we don't really know where exposure will end up because of that lousy in-camera histogram. Consequently, if you use DR400 you can be assured of not losing highlights on almost any shot you are likely to take.

Note: For best results on standard contrast scenes (no scene elements will expose higher than 0EV) use DR100 and ISO200.

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Cheers
Trevor G
Silkypix tutorials at: http://photo.computerwyse.com

Thanks, having started to learn about my new X20 and done the experiments mentioned in my posts below and come back to your original post I now fully understand it.  It makes some very interesting and instructive points. Thanks again.

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