transformation
Spatially transforms a pixmap using a custom formula.
Syntax

transformation(pm, r, expr)

pm
is a pixmap 
r
is a symbol 
expr
is an expression inr

Description
transformation(pm, r, expr)
returns the pixmap obtained from pm
by applying the mapping r ↦ expr(r)
, where r
is a twodimensional vector of pixel coordinates. The coordinate system is that of ℝ² centred at the centre of pm
.
Examples
transformation(ExampleData("harvestman"), r, ❨√abs(r[1]^1.9), r[2] − .1⋅abs(r[1])^1.2❩)