How to fix interp2() error?

I need to sample and recostract an image using interp2() function, by two methods 'linear' and 'nearest'

I have tried the code below with the method 'nearest' and it works well.

image = imread('Image1.bmp','bmp');
V = image(1:3:end,1:3:end);
Vq = interp2(V,2);

but when I tried the method 'linear', it didn't work with the error massage

Error using griddedInterpolant
Sample values must be a single or double array.

Error in interpn (line 125)
   F = griddedInterpolant(X,V,method,extrap);

Error in Sampling (line 14)
Vq = interpn(V,2);

How I can fix this Error??

Answer 1

[KSSV]

image = imread('Image1.bmp','bmp');
image = double(image) ; 
V = image(1:3:end,1:3:end);
Vq = interp2(V,2);

[layal alsini]

thax for your answer

I tried to change it into duoble .. but the output is a blank white picture !!!

[KSSV]

After interpolation before plotting....

    image=uint8(image);