Article on sRGB vs aRGB

Started Apr 9, 2008 | Discussions thread
Donald Cooper
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Re: Article on sRGB vs aRGB
In reply to sergesret, Apr 12, 2008

That's a valid point. Yes, the sensor data from a camera is sometimes called an inferred color space, a space which would be unique to each camera model sensor.

The problem is that there are some adjectives that get dropped in the discussions which can lead to conflating two entirely different critters. The inferred color space of a sensor is an input inferred color space. This thread is discussing output referred color spaces. The difference is that an input referred color space is simply sensor data whereas the output referred color space is an actual set of points in LAB space.

If that descripton of the difference isn't obvious, perhaps thinking about the process of going from one to another might help. To go from the sensor data -- or the input referred color space -- to an output color space you have to specify a white balance. But once a point is in an output color space you can map it to another output space without reference to a white balance. Indeed the concept of white balance when moving from one color space to another is as meaningless as the concept of rendering intents is when moving from the sensor data to the color space.

Though it's probably technically wrong, I find it easier to refer to "sensor data" and "color spaces" rather than to "input referred color spaces" and "output referred color spaces". To me this ensures that the two fundamentally different types of spaces aren't thought of as being equivalent.

sergesret wrote:

RAW files do embody a color space or color gamut, just not any
particular standard one. As I understand it, the color space, or
color gamut of a device depends on the color coordinates of the
device primaries. In the case of monitor it's the color of the three
phosphors. In a camera I believe it's the three different color
filters that are integrated into the sensor or the emulsion. A proper
device profile transfers these coordinates into one of the standard
reference color spaces preserving the correct relationships of the
common colors to the absolute (XYZ) color space and does it's best to
map the out of gamut colors into sensible in gamut values.

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