I'm trying to filter an image in the space domain so i'm using the conv2 function.

here's my code.

```
cd /home/samuelpedro/Desktop/APIProject/

close all
clear all
clc

img = imread('coimbra_aerea.jpg');
%figure, imshow(img);

size_img = size(img);

gauss = fspecial('gaussian', [size_img(1) size_img(2)], 50);

%figure, surf(gauss), shading interp

img_double = im2double(img);

filter_g = conv2(gauss,img_double);

```

I got the error:

```
Undefined function 'conv2' for input arguments of type 'double' and attributes 'full 3d
real'.

Error in test (line 18)
filter_g = conv2(gauss,img_double);

```

now i'm wondering, can't I use a 3 channel image, meaning color image.