On Monday 29 November 2004 22:25, Joseph Heled wrote: > (I think this has been discussed on the list before, but not sure > where/when.) > > What is the best way to achieve the following functionality - > > Given two layers L1 and L2, I want L2 limited by it's distance > from L1 > > Result <- L1 - MIN( MAX(L1 - L2), -20), 20) > > (This expression uses L1/L2 as placeholder for each pixel in all > RGB channels) > > Options: > > A. Write a plugin > > B. Write it as a script-fu (not sure if script-fu can iterate on > pixels, and what is the speed implication). And I hate scheme. > > C. Write it in python fu if I can compile it, but even though it is > probably not as universally available as scrip-fu. Can I iterate > over an image in python-fu? This one, or the C plugin. In python fu you can iterate over pixels, and still have all the ase of use of the PDB API, and from the python language itself. But it's slow to interate over pixels. If you want more speed, you either have to go to C, or use a python extension called "pyrex"which allows one to declare C langauge objects within python syntax, therefore gaining speed. But it so easy in python that I could write you the plug-in in little time - I just an not sure of what you want to achieve - Your "result" would be stored in the Layer 2 pixels? or on a 3 layer (/me thinks would be better) > D. I know I can do it with 5 layers and overlay modes. write this > as a script-fu. Not elegant and requires loads of memory for large > images. > > Layer Mode > > L1 Grain Merge > 148 Darken Only > 108 Lighten Only > L1 Grain Extract > L2 Normal > > (148/108 stand for a layer filled with gray pixels > (148,148,148)/(108,108,108) Brrr... But you could also use a pythonfu script to control teh creation and placement of these five layers. > > E. Write a generic framework which allows any kind of expression(s) > between layer(s) (Only kidding ...) No kidding - I have this code written down. But I did this for old gimp 1.3.14, and never broguthit upt o date, or wrote an itnerface for writing or compiling the generic expresion. I call it ¨ the custom layer mode", and I actually have plans to bring it back from the not-quite-dead. I will do you a template for the python plugin for now. To compile it in posix systems, just add "--enable-python" to your confgure directives. Peope on gimp-users have info on building it for windows. Regards, > > F. Anything better? Can't think of anything that surpasses "E". C will do for you, if you have patience each time you change yor source layers. > > > -Joseph >
