The build in conversion of RGB (color map) sources to Value (grayscale map) inputs is wrong. It uses RGBA and not RGB when converting to grayscale.
I tested this with several components (Threshold, Levels, Brightness / Contrast).
And in several component specific help entries help states that an average of RGB is used.
I'm not sure when this behaviour started, but it surely is not very logical that alpha is used in the conversion.
I suggest showing mandatory remappers when going fr om color map -> grayscale map, wh ere alternative conversion methods can be chosen (e.g. "Average RGBA", "Average RGB", "Red", "Green", "Blue", "Alpha", "Max RGB", Average(R,G,B) * A, etc)
Attached is a simple filter - open it, enter the editor and try out the "New Alpha" slider...
Map Conversion Bug.ffxml
Njyldgarkn sample cache!
|Posted: October 31, 2011 1:40 pm|
This conversion is correct. Alpha is used in the conversion since early betas of FF 1.0 So don't worry, everything is ok
But FF reference might really contain some errors, so I suppose we'll revise this.
The idea about remappers between 'green' components has already came to us, but we decided to put it off.
|Posted: January 30, 2012 6:01 am|
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