title: Overlays author: Tim Holy order: 60 ...
Frequently one wants to combine two (or more) grayscale images into a single
colorized image. Images defines an AbstractArray type, Overlay, making
this straightforward.
To create an overlay, use the following syntax:
O = Overlay((gray1,gray2,...), (color1,color2,...), (clim1,clim2,...))
Here gray1 and gray2 are the arrays representing individual "channels" of
information, each equivalent to a grayscale image. color1 and color2 are
the Colors that will be used for the
corresponding grayscale arrays; for example, to put gray1 in the red channel,
you'd use color1 = RGB(1,0,0). (You can choose any RGB value you want, it
doesn't have to be a "pure" RGB channel.) Finally, clim1 and clim2
represent the intensity-scaling applied to each image; setting clim1 = (400,3000) would send any values in gray1 less than 400 to black, and any
values bigger than 3000 to red, with other values between encoded linearly.
Once constructed, an Overlay acts as an Array{RGB}. You can embed it in an
Image or just use it directly.