diff --git a/skimage/rank/_core8.pyx b/skimage/rank/_core8.pyx
index 87588813..19e09aec 100644
--- a/skimage/rank/_core8.pyx
+++ b/skimage/rank/_core8.pyx
@@ -23,6 +23,14 @@ cdef inline np.uint8_t uint8_min(np.uint8_t a, np.uint8_t b): return a if a <= b
 # 8 bit core kernel
 #---------------------------------------------------------------------------
 
+cdef inline void histogram_increment(Py_ssize_t* histo,float *pop,np.uint8_t value):
+    histo[value] += 1
+    pop[0] += 1.
+
+cdef inline void histogram_decrement(Py_ssize_t* histo,float *pop,np.uint8_t value):
+    histo[value] -= 1
+    pop[0] -= 1.
+
 cdef inline np.uint8_t is_in_mask(Py_ssize_t rows, Py_ssize_t cols,Py_ssize_t r, Py_ssize_t c,np.uint8_t* mask):
     """ returns 1 if given(r,c) coordinate are within the image frame ([0-rows],[0-cols]) and
         inside the given mask
@@ -157,9 +165,7 @@ cdef inline _core8(np.uint8_t kernel(Py_ssize_t*, float, np.uint8_t, float, floa
             cc = c - centre_c
             if selem[r, c]:
                 if is_in_mask(rows,cols,rr,cc,mask_data):
-                    value = image_data[rr * cols + cc]
-                    histo[value] += 1
-                    pop += 1.
+                    histogram_increment(histo,&pop,image_data[rr * cols + cc])
 
     r = 0
     c = 0
@@ -176,16 +182,13 @@ cdef inline _core8(np.uint8_t kernel(Py_ssize_t*, float, np.uint8_t, float, floa
                 rr = r + se_e_r[s]
                 cc = c + se_e_c[s]
                 if is_in_mask(rows,cols,rr,cc,mask_data):
-                    value = image_data[rr * cols + cc]
-                    histo[value] += 1
-                    pop += 1.
+                    histogram_increment(histo,&pop,image_data[rr * cols + cc])
+                    
             for s in range(num_se_w):
                 rr = r + se_w_r[s]
                 cc = c + se_w_c[s] - 1
                 if is_in_mask(rows,cols,rr,cc,mask_data):
-                    value = image_data[rr * cols + cc]
-                    histo[value] -= 1
-                    pop -= 1.
+                    histogram_decrement(histo,&pop,image_data[rr * cols + cc])
 
             # kernel --------------------------------------------------------------------
             out_data[r * cols + c] = kernel(histo,pop,image_data[r * cols + c],p0,p1,s0,s1)
@@ -200,16 +203,13 @@ cdef inline _core8(np.uint8_t kernel(Py_ssize_t*, float, np.uint8_t, float, floa
             rr = r + se_s_r[s]
             cc = c + se_s_c[s]
             if is_in_mask(rows,cols,rr,cc,mask_data):
-                value = image_data[rr * cols + cc]
-                histo[value] += 1
-                pop += 1.
+                histogram_increment(histo,&pop,image_data[rr * cols + cc])
+
         for s in range(num_se_n):
             rr = r + se_n_r[s] - 1
             cc = c + se_n_c[s]
             if is_in_mask(rows,cols,rr,cc,mask_data):
-                value = image_data[rr * cols + cc]
-                histo[value] -= 1
-                pop -= 1.
+                histogram_decrement(histo,&pop,image_data[rr * cols + cc])
 
         # kernel --------------------------------------------------------------------
         out_data[r * cols + c] = kernel(histo,pop,image_data[r * cols + c],p0,p1,s0,s1)
@@ -221,16 +221,13 @@ cdef inline _core8(np.uint8_t kernel(Py_ssize_t*, float, np.uint8_t, float, floa
                 rr = r + se_w_r[s]
                 cc = c + se_w_c[s]
                 if is_in_mask(rows,cols,rr,cc,mask_data):
-                    value = image_data[rr * cols + cc]
-                    histo[value] += 1
-                    pop += 1.
+                    histogram_increment(histo,&pop,image_data[rr * cols + cc])
+
             for s in range(num_se_e):
                 rr = r + se_e_r[s]
                 cc = c + se_e_c[s] + 1
                 if is_in_mask(rows,cols,rr,cc,mask_data):
-                    value = image_data[rr * cols + cc]
-                    histo[value] -= 1
-                    pop -= 1.
+                    histogram_decrement(histo,&pop,image_data[rr * cols + cc])
 
             # kernel --------------------------------------------------------------------
             out_data[r * cols + c] = kernel(histo,pop,image_data[r * cols + c],p0,p1,s0,s1)
@@ -245,16 +242,13 @@ cdef inline _core8(np.uint8_t kernel(Py_ssize_t*, float, np.uint8_t, float, floa
             rr = r + se_s_r[s]
             cc = c + se_s_c[s]
             if is_in_mask(rows,cols,rr,cc,mask_data):
-                value = image_data[rr * cols + cc]
-                histo[value] += 1
-                pop += 1.
+                histogram_increment(histo,&pop,image_data[rr * cols + cc])
+
         for s in range(num_se_n):
             rr = r + se_n_r[s] - 1
             cc = c + se_n_c[s]
             if is_in_mask(rows,cols,rr,cc,mask_data):
-                value = image_data[rr * cols + cc]
-                histo[value] -= 1
-                pop -= 1.
+                histogram_decrement(histo,&pop,image_data[rr * cols + cc])
 
         # kernel --------------------------------------------------------------------
         out_data[r * cols + c] = kernel(histo,pop,image_data[r * cols + c],p0,p1,s0,s1)