parameters: (self, mask=None, extrema=None)
return_statement: return self.im.histogram()
docstring: Returns a histogram for the image. The histogram is returned as
          a list of pixel counts, one for each pixel value in the source
          image. If the image has more than one band, the histograms for
          all bands are concatenated (for example, the histogram for an
          "RGB" image contains 768 values).
  
          A bilevel image (mode "1") is treated as a greyscale ("L") image
          by this method.
  
          If a mask is provided, the method returns a histogram for those
          parts of the image where the mask image is non-zero. The mask
          image must have the same size as the image, and be either a
          bi-level image (mode "1") or a greyscale image ("L").
  
          :param mask: An optional mask.
          :param extrema: An optional tuple of manually-specified extrema.
          :returns: A list containing pixel counts.
docstring_summary: Returns a histogram for the image. The histogram is returned as
          a list of pixel counts, one for each pixel value in the source
          image. If the image has more than one band, the histograms for
          all bands are concatenated (for example, the histogram for an
          "RGB" image contains 768 values).
docstring_tokens: Returns a histogram for the image . The histogram is returned as a list of pixel counts one for each pixel value in the source image . If the image has more than one band the histograms for all bands are concatenated ( for example the histogram for an RGB image contains 768 values ) .
function: def histogram(self, mask=None, extrema=None):
          """
          Returns a histogram for the image. The histogram is returned as
          a list of pixel counts, one for each pixel value in the source
          image. If the image has more than one band, the histograms for
          all bands are concatenated (for example, the histogram for an
          "RGB" image contains 768 values).
  
          A bilevel image (mode "1") is treated as a greyscale ("L") image
          by this method.
  
          If a mask is provided, the method returns a histogram for those
          parts of the image where the mask image is non-zero. The mask
          image must have the same size as the image, and be either a
          bi-level image (mode "1") or a greyscale image ("L").
  
          :param mask: An optional mask.
          :param extrema: An optional tuple of manually-specified extrema.
          :returns: A list containing pixel counts.
          """
          self.load()
          if mask:
              mask.load()
              return self.im.histogram((0, 0), mask.im)
          if self.mode in ("I", "F"):
              if extrema is None:
                  extrema = self.getextrema()
              return self.im.histogram(extrema)
          return self.im.histogram()
function_tokens: def histogram ( self , mask = None , extrema = None ) : self . load ( ) if mask : mask . load ( ) return self . im . histogram ( ( 0 , 0 ) , mask . im ) if self . mode in ( "I" , "F" ) : if extrema is None : extrema = self . getextrema ( ) return self . im . histogram ( extrema ) return self . im . histogram ( )