A Computational Introduction to Digital Image Processing, 2nd Edition

344 A Computational Introduction to Digital Image Processing, Second Edition

Python

def disttrans(image,mask):

backmask = np.rot90(np.rot90(mask))

mr,mc = mask.shape

if mr%2 == 0 or mc%2 == 0:

raise ValueError("Error:

Mask must have odd numbers of rows and

columns")

r,c = image.shape

nr = (mr-1)/2

nc = (mc-1)/2

image2 = np.float64(np.pad(image,[nr,nc],mode=’edge’))

image2[np.where(image2==0)]=float(’inf’)

image2[np.where(image2==1)]=0

for i in range(r):

for j in range(c):

image2[i+nr,j+nc] = (image2[i:i+mr,j:j+mc]+mask).

min()

for i in range(r)[::-1]:

for j in range(c)[::-1]:

image2[i+nr,j+nc] = (image2[i:i+mr,j:j+mc]+backmask).min()

return image2[nr:nr+r,nc:nc+c] ...