add scale bar to image

How to add scale on the horizontal axis on an image (not on a graph). the image length density is 0.101mm/pixel. How can i just show the scale below the image.

Answer 1

[David Goodmanson]

Hi Irfan,

A = imread('your_image.whatever');
sizh = size(A,2); % or any other way to find the number of pixels in the horizontal  
                  % direction if you are not using imread.
xmax = sizh*.101;
image([0 xmax],[],A)

With the second, empty argument in image( ) you can do the same thing in the y direction. ,

[Irfan Tahir]

thanksalot,but using image command, the colormap seems little off.

[David Goodmanson]

Hi Irfan,

take a look at 'imagesc'.

Answer 2

[Joshua Brockman]

I often use Matlabs quiver plot with the arrow head turned off to add a vector (which will appear as a bar) to your image.

The way I do this:

figure; imshow(YourImage) hold on

% Pixel Size = size of pixel within your image % Scalebar_length = Desired scale bar length % x_location and y_location are wherever you want your scale bar to appear. quiver(x_location,y_location,Scalebar_length/PixelSize,0,'ShowArrowHead','off')

[Rob Campbell]

I tried this method and noticed when I labelled the bar by putting text where the center of the bar should be (with 'horizontalalignment' as 'center'), the text was always offset a bit. In figuring that out I found that the bar produced with quiver is a little longer than it ought to be. Better to use plot to do that.