If you have an image, that starts out as all zeros, and a set of coordinates that define where the lines go, you can simply add 1 to the image everytime you encounter one of those coordinates. Like if you have a set of (x,y) coordinates of a line (perhaps use Bresenham's line algorithm ) then do this
heatmapImage = zeros(rows, columns)
for k = 1 : length(x)
row = round(y(k));
col = round(x(k));
% Don't let go outside image.
if row > rows
row = rows;
end
if col > columns
col = columns;
end
if row < 1
row = 1;
end
if col < 1
col = 1;
end
% Increment the value.
heatmapImage(row, col) = heatmapImage(row, col) + 1;
end
Repeat that for every set of x,y data you have, then display the resulting image:
imshow(heatmapImage, []);
colormap(jet(256));
colorbar;
