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I have a four band aerial photography raster. The bands contain Red, Green, Blue, and IR data.

Using GDALInfo we get something like this currently:

Band 1 Block=2933x1 Type=UInt16, ColorInterp=Undefined
Band 2 Block=2933x1 Type=UInt16, ColorInterp=Undefined
Band 3 Block=2933x1 Type=UInt16, ColorInterp=Undefined
Band 4 Block=2933x1 Type=UInt16, ColorInterp=Undefined

The first three bands can be set to have a colour Interpretation of RGB respectively (GIS' get flaky if they're not set it seems).

But what should the ColorInterp be for the fourth, InfraRed band? Left Undefined? Or is there a setting for IR?

Thanks.

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Did you try "Alpha"? That's what I got for a 4-band TIFF I had handy. – blah238 Mar 4 '13 at 20:55
    
@blah238 Problem there is, I think some applications will assume alpha is what it says (transparency) and I'll get unexpected results. – GIS-Jonathan Apr 19 '13 at 10:25

You can indeed leave the NIR band as Undefined, there is nothing wrong with that.

If you set it to alpha, some software will handle it as a transparency layer.

Note that you may prefer an pseudo-color NIR composite by default instead of the true color image, then you can use "red" for band 4, "green" for band 3 and "blue" for band 2.

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