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Subject: Re: Exposure to the right and tone placement


Thank you for a most informative post. The Leaf equipment and software are awesome and your background as an electronic engineer working with CCD sensors means that you know how to interpret the data.

It would be nice to Tom Knoll would give us some of the features you mention, but in the meantime interested users can use Dave Coffin's DCRaw, which has options to output the sensor data without white point correction, gamma correction, or application of any tone curve. One can then examine the data in Photoshop as an untagged RGB.

No one doubts Bruce's statement about the linearity of the digital sensors, but there is some disagreement about how best to make use of the data. Rendering of the raw image is not often discussed in books for the masses, and the only place I've seen it discussed in any detail is in Andrew Rodney's writings (Color Management for Photographers and online forums. As you know, this process involves mapping of the high dynamic range of a scene into the dynamic range of output devices (the development process you talk about). In many cases, out of gamut colors are also remapped.

The much beloved ProPhotoRGB is designed for rendered data and is not really appropriate for representation of the original scene, so it is not well suited for analysis of the original raw image even if is converted to linear gamma.

In summary, I agree that it would be nice to know a bit more of how ACR does map the RAW data to the final edit space. However, ACR with ProPhotoRGB meets most needs.

Bill Janes


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Exposure to the right and tone placement =>


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