Colored image by Gabor Filters

Question

I am using a Gabor Filter Code and Everything seems to run fine but I am having Problem with Output Image. The Code I am using belongs from here : Gabor Filters

I created [4x8] filters with 8 orientations each with varying wavelength.

Now I gave an image as input:

So I got output as:

Am I not Supposed to get some image in Black and White.
I mean why is it colored.
When I check the dimension using ndims(imgS) It tell that image is 2-D.

For the sake of some clarity Here is the code where Image is convolved with above patches.:

function [img]=Convolve_Gabor(R,C,GW,img)
%if not grayscaled then grayscale it
if ndims(img)>2
    img=rgb2gray(img);
end

%Convert to Double so that its accepteble everywhere
img=im2double(img);

% Store the original size.
[m,n] = size(img);

%{
 The minimum amount of padding is just "one side" of the filter.
 We add 1 if the image size is odd.
 assuming the filter size is odd.
%}

pR = (R-1)/2; % make pR half of R
pC = (C-1)/2; % make pC half of C

if rem(m,2) ~= 0; pR = pR + 1; end; % if image height is odd make pR even
if rem(n,2) ~= 0; pC = pC + 1; end; % if image width is odd make pC even
img = padarray(img,[pR pC],'pre'); % Pad image to handle circular convolution.

% Pad all the filters to size of padded image.
% We made sure padsize will only be even, so we can divide by 2.
padsize = size(img) - [R C];
GW = cellfun( @(x) padarray(x,padsize/2),GW,'UniformOutput',false);

imgFFT = fft2(img); % Pre-calculate image FFT.
imgfilt={};
for i=1:length(GW)
    filter = fft2( ifftshift( GW{i} ) ); % See Numerical Recipes.
    imgfilt{i} = ifft2( imgFFT .* filter ); % Apply Convolution Theorem.
end

%# Sum the responses to each filter. Do it in the above loop to save some space.
imgS = zeros(m,n);

for i=1:length(imgfilt)
    imgS = imgS + imgfilt{i}(pR+1:end,pC+1:end); % Just use the valid part.
end
disp(ndims(imgS));
figure,imagesc(abs(imgS)),hold on;

Answer 1

Just because an image only has one channel, i.e., the data is a 2-D matrix, doesn't mean that it can't be transformed to three-dimensional RGB space. This technique is referred to as indexed color (as opposed to truecolor). It looks like Matlab is using the default jet colormap to transform the data to color. If you want the image to display as grayscale, use the colormap function after plotting:

colormap(gray(256));

See this blog post from The MathWorks for further details.