scaling

[Gabriel Genellina]

En Tue, 01 May 2007 11:22:28 -0300, Ashok <ashokagk at gmail.com> escribió:

> IDL language contains a function called BYTSCL to scale all values of
> Array that lie in the range (Min £ x £ Max) into the range (0 £ x £
> Top). Is there a similar function available in python?
>
> I need this to scale the pixel values of an image using PIL.

Maybe PIL contains something built in, but if all else fails, you could  
write it in Python:

def bytsclGen(data, minvalue=None, maxvalue=None, top=255):
   if minvalue is None: minvalue = min(data)
   if maxvalue is None: maxvalue = max(data)
   for x in data:
     if x<minvalue: yield 0
     elif x>maxvalue: yield top
     else: yield (x-minvalue)*top/(maxvalue-minvalue)

def bytscl(data, minvalue=None, maxvalue=None, top=255):
   return list(bytsclGen(data, minvalue, maxvalue, top))

-- 
Gabriel Genellina