Bug: Color Map -> Grayscale map conversion wrong

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).

Quote

Help states: If a full-color image is connected to a non-color map input, the color and alpha channel of the image are ignored, and only the brightness is used. Technically, values for the mapped non-color parameter are calculated as follows. The supplied image is converted into grayscale by averaging its R, G, and B channels, and this grayscale level is used to calculate the parameter value: white areas correspond to the maximum value, black areas to minimum value, and the values in-between are represented by intermediate grayscale levels. (source)

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