Example 1: Retrieve pixel value of row=417 and col=459

import arr
img = GetImageMatr('Image') # on RGB images use Image.I to retrieve intensity plane
ROWS,COLS = img.dim()
print 'image size ',ROWS,COLS

row = 417 # row is x when measuring with pixels as reference system
col = 459 # column is y
pixel = img[row*COLS+col]

print ' row, column, value ',row,col,pixel

ScorpionImage class simplifies image pixel access

def CreateScorpionImage(rows,cols):

  import arr
  
  class ScorpionImage:
    def __init__(self,rows=0,cols=0):
      if rows * cols > 0:
        self.im=arr.uint8Mat(rows,cols)

    # return number rows in image
    def Rows(self):
       R,C = self.im.dim()
       return R

    # return number columns in image
    def Columns(self):
       R,C = self.im.dim()
       return C

    # transfers image to scorpion image by name
    def SetImageMatr(self,name):
      SetImageMatr(name,self.im)

    # reads scorpion image to class
    def GetImageMatr(self,name):
      self.im = GetImageMatr(name)

    # resets image to zero
    def Reset(self):
      arr.setArr(self.im,0)

    # set pixel of image to value
    def Set(self,row,col,value):
      R,C=self.im.dim()
      self.im[row*C+col]=value

    # get image pixel value
    def Get(self,row,col):
      R,C=self.im.dim()
      return self.im[row*C+col]

  return ScorpionImage(rows,cols)

Example 2: Manipulate a Scorpion Image using ScorpionImage instance

image = CreateScorpionImage(0,0)
image.GetImageMatr('Image') # on RGB images use Image.I to retrieve intensity plane
for i0 in range(40):
  p = image.Get(i0*10,i0*10)
  p += 100
  if p>255: p=255
    image.Set(i0*10,i0*10,p)

image.SetImageMatr('Image')