new_contents: import numpy
  
  def OpticalDensityFwd(I):
      '''
      Transforms input RGB image "I" into optical density space for color deconvolution.
      *Inputs:
          I (rgbimage) - a floating-point RGB image with channel ranges 0-255.
      *Outputs:
          Out (rgbimage) - a floating-point image of corresponding optical 
                           density values.
      *Related functions:
          OpticalDensityInv, ColorDeconvolution, ColorConvolution
      '''
      
      return (-(255*numpy.log(I/255))/numpy.log(255));
  
subject: Create OpticalDensityFwd.py