
Operations on Images É 389
3. Run the filter over image g using imfilter function and display the output image.
>> g_edge = imfilter(g,h); imshow(g_edge)
Thus, we see that the sobel filter has detected edges as shown in g_edge image in Figure 13.14.
Sobel filter is nothing but a 3 × 3 filter, which can be viewed by simply typing h after step 2,
and pressing return.
>> h
h =
1 2 1
0 0 0
-1 -2 -1
There are several other linear spatial filters predefined in IPT, such as gaussian, prewitt, average,
which can be used through fspecial function.We can similarly define our own filter as an m × n
matrix with certain values and use it with imfilter