function emap = canny1(img, tlow, thigh, fsize, sigma)
    % INITIALIZING EMAP:
    emap = zeros(size(img));
    % CONVERTING TO GRAY SCALE:
    size(size(img))
    %img = rgb2gray(img);
    % SMOOTHING FILTER | REDUCE NOISE:
    filter = fspecial('gaussian', fsize, sigma);
    img = im2double(img);
    img = imfilter(img, filter);
    % FINDING IMAGE DERIVATIVES:
    % dx = img - [img(2:end, :); img(1,:)];
    % dy = img - [img(:,2:end) img(:,1)];
    [dx, dy] = gradient(img);
    % GRADIENT MAGNITUDE:
    magnitude = sqrt(dx.^2 + dy.^2);
    % GRADIENT DIRECTION:
    direction = atan2(dy, dx) * (180.0 / pi);
    % ROUNDING DIRECTION:
    negatives = direction < 0;                  % Getting the negative value locations.
    direction = direction + negatives * 180;    % Correcting them.
    % SORTING DIRECTIONS USING HISTOGRAM COUNT:
    roundAngTo = [-inf, 45, 90, 135, inf];
    % W-E,         NE-SW,         N-S,           NW-SE
    % [0-45 -> 1], [45-90 -> 2] , [90-135 -> 3], [135-180 -> 4]
    [notNeeded, newDirection] = histc(direction, roundAngTo);
    nonSupress = magnitude;
    % NON-MAXIMUM SUPPRESSION:
    for m = 2:(size(img, 1) - 1)
        for n = 2:(size(img, 2) - 1)
            switch newDirection(m,n)
                case 1
                % INTERPOLATE [W-E]:
                if((magnitude(m,n) > magnitude(m - 1, n)) || (magnitude(m,n) > magnitude(m + 1, n)))
                    nonSupress(m,n) = 0;
                    if(magnitude(m,n) > thigh)
                        emap(m,n) = 1;
                    elseif(magnitude(m,n) > tlow)
                        % CHECK PERPENDICULAR:
                        if((magnitude(m, n - 1) > thigh) || (magnitude(m, n + 1) > thigh))
                            emap(m,n) = 1;
                        end
                    end
                end
                case 2
                % INTERPOLATE [NE-SW]:
                if((magnitude(m,n) > magnitude(m + 1, n - 1)) || (magnitude(m,n) > magnitude(m - 1, n + 1)))
                    nonSupress(m,n) = 0;
                    if(magnitude(m,n) > thigh)
                        emap(m,n) = 1;
                    elseif(magnitude(m,n) > tlow)
                        % CHECK PERPENDICULAR:
                        if((magnitude(m - 1, n - 1) > thigh) || (magnitude(m + 1, n + 1) > thigh))
                            emap(m,n) = 1;
                        end
                    end
                end
                case 3
                % INTERPOLATE [N-S]:
                if((magnitude(m,n) > magnitude(m, n - 1)) || (magnitude(m,n) > magnitude(m, n + 1)))
                    nonSupress(m,n) = 0;
                    if(magnitude(m,n) > thigh)
                        emap(m,n) = 1;
                    elseif(magnitude(m,n) > tlow)
                        % CHECK PERPENDICULAR:
                        if((magnitude(m + 1, n) > thigh) || (magnitude(m - 1, n) > thigh))
                            emap(m,n) = 1;
                        end
                    end
                end
                case 4
                % INTERPOLATE [NW-SE]:
                if((magnitude(m,n) > magnitude(m - 1, n - 1)) || (magnitude(m,n) > magnitude(m + 1, n + 1)))
                    nonSupress(m,n) = 0;
                    if(magnitude(m,n) > thigh)
                        emap(m,n) = 1;
                    elseif(magnitude(m,n) > tlow)
                        % CHECK PERPENDICULAR:
                        if((magnitude(m - 1, n + 1) > thigh) || (magnitude(m + 1, n - 1) > thigh))
                            emap(m,n) = 1;
                        end
                    end
                end
            end
        end
    end

    % CONVERTING TO BINARY MASK:
    nonSupress = nonSupress > 0;
    % SHOW RESULT:
    subplot(2,3,1); imshow(img), title('Smoothed Image')
    subplot(2,3,2), imshow(magnitude), title('Magnitude');
    subplot(2,3,3), imshow(dx), title('dx');
    subplot(2,3,4), imshow(dy), title('dy');
    subplot(2,3,5), imshow(nonSupress), title('Supression');
    subplot(2,3,6), imshow(emap), title('EMAP');
    %figure; imagesc(nonSupress);
    %figure; imshow(emap,[]);
end