On Dec 21, 2007 4:49 PM, Brian Vanderburg II wrote:
Is there a plugin (or high speed script-fu) that would allow me to enter
a math expression and from it create the pixel data also given a
'viewport range'.
XMin: -1
XMax 1
YMin -1
Ymax: 1
UseGraient: no
Expr: red=sin(2*pi*x*y)/2+0.5;green=...,...
or
UseGradient: yes
Simple gradient application is best done using 'gradient map' filter.
Although since you're running windows, that may be slower.
Expr: offset=sin(2*pi*x*y)
Or something like that. I imagine a script-fu could be done that could
take the viewport, gradient, and expression and somehow execute the
expression and plot the pixels, but it seems like script-fu would be
somewhat slow. I've created my own expression evaluation library which
would easily provide all the math support I need, but don't know much
about making GIMP plugins and since I'm only on Windows now I've had
problems trying to compile glib/gtk under msys/mingw, plus it is C++
except an older version which is C.
Brian Vanderburg II
I recommend using PyGimp in combination with Numpy.
for example, here is some python source code for the first 'red' example
# it is assumed that x,y are 2d arrays
# like
# x =
# 012
# 012
# 012
#
# y =
# 000
# 111
# 222
red = numpy.sin((2 * pi) * x * y) / 2 +0.5
# calculate green, blue.. here
# ..
# expand the range (0..1) -> (0..255) and convert to 8bit integers
# you would need to account for the possibility of an alpha channel here, too.
result = numpy.hstack ( (red * 255).astype('B'), (green *
255).astype('B'), (blue * 255).astype('B'))
# result.tostring() can now be written to a GIMP pixel region
