Line of controlled thickness in image

Hey!

I have a grayscale image (I) and I would like to plot a line with a controlled thickness in it.

I know the coordinates of the line x=[x0,xf], y=[y0,yf], and lets say the thickness I want is "t", in pixels.

I can do

imshow (I)

line(x,y, 'LineWidth', linewidthvalue)

But the line here has a width that depends on how much I zoom in in the image, since in 'LineWidth' the width is defined by 1/72 inches, not in pixels. Is there any way to change that, namely, to fix the width of the line to a certain number of pixels?

Thanks in advance :)

Answer 1

[DGM]

This is one way to draw a line on the image itself.

% it's assumed that this is a color image
% if it's not, it needs to either be mxnx3
% or you'll have to get rid of the line color
A = repmat(imresize(imread('cameraman.tif'),[700 700]),[1 1 3]);

% parameters
thisline = [50 550; 250 300; 545 640; 431 691; 545 681];
linecolor = [0 255 255];
linewidth = 10;

% construct the line mask
h = imshow(A);
h.Visible = 'off';
L = images.roi.Polyline(gca);
L.Position = thisline;
mask = imdilate(createMask(L),strel('disk',floor(linewidth/2)));

% apply the mask
A = uint8(double(A).*~mask + permute(linecolor,[1 3 2]).*mask); % assuming A is uint8

% then just save the image or do whatever
imshow(A)

If you have Computer Vision Toolbox, there is also insertshape().

https://www.mathworks.com/help/vision/ref/insertshape.html