Vector 'x' is the linear interpolator over each of the 'colors', i.e: over the 8 band RGB basis rainbow. Next, we will create the complete 'rainbow' colormap from interpolation. There are lot of "colormap" for specific rendering of 3D plots.

The relative perception of the brightness of R,G,B of average person has been normalised NTSC => 0.299*Red+0.587*Green+0.114*Blue = 1. At the image capture, the gray level is pro- portioned to this NTSC ratio to produce the 3 RGB components. The NTSC conversion is done on the *.raw image, quantisation follows. Even if the sky looks blue, there is little blue in nature, not much red, nature is mostly green to human eye.

Create the rainbow colormap index 0..255

Here, we freak Smath wrt index not universal i.e: let force it to tabulate start @ 0. The rainbow colormap has been sanity checked. The band interpolator is used once and we re-install "band" ... [next] ...

... [next], we install a "mapping function", a function that takes "var" as the user grayscale image as its argument. This triplet function will now map/interpolate each R, G, B component against the grayscale band.

Smath 6179 does not vectorise this system. 'linterp' is an interpolation function but not a "scalar function". We will map [RGB] in discrete step, stack over 'n' and unest each [Red, Green, Blue].

Here is the rainbow vectorise companion

Set the width