gistfile1.txt

def integral_image(img):
    gnp = img.toGray().getNumpy()[:,:,0]
    retVal = np.zeros(gnp.shape);
    for i in range(gnp.shape[0]):#width
        for j in range(gnp.shape[1]): #height          
            if( i > 0 and j > 0):
                retVal[i,j] = retVal[i,j-1]; #add the entry above us
                retVal[i,j] += retVal[i-1,j] #add everything to our left
                retVal[i,j] -= retVal[i-1,j-1] #subtract off everything we count twice
                retVal[i,j] += gnp[i,j] #our value
            elif( i == 0 and j > 0): #add our value to the value above
                retVal[i,j]=retVal[i,j-1]+gnp[i,j]
            elif( i > 0  and j == 0 ): # add our value to the left
                retVal[i,j]=retVal[i-1,j]+gnp[i,j]
            else: # start
                retVal[i,j] = gnp[i,j]
    return retVal;

def integral_image_slow(img):
    gnp = img.toGray().getNumpy()[:,:,0]
    retVal = np.zeros(gnp.shape);
    for i in range(gnp.shape[0]):
        for j in range(gnp.shape[1]):
            retVal[i,j] = np.sum(gnp[0:i,0:j])
    return retVal