ABSTRACT
This chapter introduces narrowband data into an RGB image. The individual R, G and B filters typically have a broad pass-band of about 100 nm each, and even if the red and green filters exclude the dominant yellow sodium vapor lamp wavelength they will pass considerable light pollution from broadband light sources and shot noise. The opacity setting proportionally mixes the global result with the underlying layer and a mask does the same but at a pixel level. Several Internet resources specify the corresponding mathematical formula for the Photoshop blending modes and it is possible to replicate these using the PixelMath tool. Narrowband Imaging is impossible to impart a regime on full narrowband imaging. The only limitation is time and imagination. The basic processing follows two paths; the color information and the luminance. The luminance processing is identical to that in RGB imaging with one exception: the source of the luminance information.
