HDR experiment

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Sand sculpture, early morning.This is a visual preview of some of the data in a multi-layered 32 bit high dynamic range (HDR) image file. That sounds confusing, but it's important to clarify that, even when looking at an actual HDR image in Photoshop, you're only seeing a preview of a specific state. So, much more simply, this is a JPEG saved from the HDR file. The HDR file is unscathed, with different levels of light and color still available with the tweak of a slider. You're absolutely right if you think it just looks like a JPEG. The magic is in the availability of the additional data in the original.

I'm using Photoshop 10, part of the CS3 suite, to "Merge Photos to HDR" (It's very much like the process in CS2, but the alignment functionality has been improved.) This morning I ran over to the Central Parklet to take these shots. I set the camera on manual so that I could keep all of the settings constant for a series of seven images, each with a different exposure of the same scene. It's important to keep aperture and focus the same for each shot; any of the auto features in the camera would have adjusted those aspects to try to compensate for the changing exposure settings. Also important was a tripod and cable release.

What I think is really worth noting here is that I have the shot. I know very close to nothing about this professional camera. Adding to my camera confusion is the fact that the "Merge to HDR" command in Photoshop opens a separate small application within Photoshop, similar to Camera Raw, with a number of tools, choices, dialogs, and methods that fortunately responded to guessing but obviously have a great deal of potential. The technology allowed me to gather enough visual data to make up for my short comings as a photographer.

Since what I'm doing is merging the data from different exposure lengths, I'm predicting that very soon this process will happen in camera. When you click the shutter, information is recorded several times throughout the length of time the shutter is open. Those additional packets of light data will be stored directly in the image file- which will come out of the camera as an HDR image with adjustable light levels. The HDR merge function in Photoshop will be outdated before it gets fully developed.


dave said:

What may be interesting to note is that the photos were taken around 6 am on a very overcast morning. I was standing in deep shade, but can still see detail in the sand at my feet, in the maple trunk and on the concrete cylinders. There's also detail right in front of the spot lights- the leaves are bright green and the twigs brown, with very little noticeable burn out.

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