Displaying an axis scale in mm rather than pixels

I have written a code for image analysis that uses the number of pixels throughout to calculate lengths. Now I want to plot graphs and have my axis reading in millimetres rather than number of pixels. I have a calibration factor calculated, is there a simple way I can have axis in millimetres. I need this code to work for multiple pictures therefore using the xticks and xticklabels method would help.

Answer 1

[Looky]

It's a bit tricky without any example data, but this should do the trick.

    conversion=0.1; % in mm/pixel
    addMM=@(x) sprintf('%.3fmm',x*conversion);
    xticklabels(cellfun(addMM,num2cell(xticks'),'UniformOutput',false));
    yticklabels(cellfun(addMM,num2cell(yticks'),'UniformOutput',false));

You can fine tune how many digits are displayed by editing the '%.3fmm' in the second line(see formatSpec). Change the variable conversion to your needs. It's in mm per pixel. Hope that helps, if not, just ask. Note that Matlab still treats the axis in Pixel, but displays the converted mm. If you make changes to xtick and ytick, you have to call the above lines again.

[Robbie McDermott]

That is fantastic, does exactly what I wanted it to! Thank you, saved me two week work!

[Stelios Fanourakis]

It is a very nice solution, indeed. Thanks a lot as well. I'd like to ask whether there is a way to have more steps, like every 50 mm or every 10 mm, instead of almost a 100 mm

Answer 2

[elvis okacha]

Look I'm trying to implement your solution within a button program in my guitar,but I still get error that 'undefined variable 'xticks''.allitle new to Matias.is there some additional code on the use of stick and xticklabels?kindly

[Walter Roberson]

Which MATLAB release are you using? xticks() is R2016b and later. Before that you had to set the XTicks property of the axes.

[elvis okacha]

R2015a.what do I add to looky's code to achieve the conversion?

[Walter Roberson]

xticks = get(gca, 'XTicks');
yticks = get(gca, 'YTicks');

before the code you posted earlier.

[elvis okacha]

Thanks.though I'm getting an error that 'there is no XTicks property on the Axes class'.ive attached a picture

[Walter Roberson]

xticks = get(gca, 'XTick');
yticks = get(gca, 'YTick');

[elvis okacha]

Yes I tried that already.but error then occurs on the label saying 'undefined function or variable 'xticklabels'.when I replace with 'xticklabel',I get same error

[elvis okacha]

Any help?

[Walter Roberson]

set() the axes XTickLabels and YTickLabels properties instead of calling xticklabels() and yticklabels()

[elvis okacha]

Ok thanks

Answer 3

[elvis okacha]

Sorry.'looky' not 'look'