How can I make my scatter plot markers opaque, or semi transparent?

I am only 2 weeks old in computer programming so please bare with me my background is neuroscience!

So I have come far enough in a script to create a scatter plot and overlay it onto an image. I have managed to have the colour as a function of z-scores (Z) and size as a function of variable durS - which is awesome. All I need to know now is how to make the markers semi transparent so that I can see the overlap of markers and the image underneath.

Here is my code so far:

X = alldatamat(:,2); %xcoor 
Y = alldatamat(:,3); %ycoor 
Z = (pupilz); 
%colour as a function of z scores 
durS = alldatamat(:,4); %size of marker as a function of duration
figure(1); imshow(imselect); % brings up selected image 
hold on; 
Z = remap(Z,0,255); %% this is a made up function to retain colours when superimposed on image 
ps = scatter(X,Y,durS,Z,'filled');

please help me make markers semi transparent (I tried alpha and played around with a few other things), or maybe suggest another way I can do this. In your answer please assume I know the least! Thanks!

[Mathieu NOE]

hello

can you share the data and image as well ? (use the paperclip button)

Answer 1

[Mathieu NOE]

hello again

a small demo to see the effect of the scatter function parameter 'MarkerFaceAlpha' on the dots transparency

with 'MarkerFaceAlpha' = 1 : no transparency

with 'MarkerFaceAlpha' < 1 : it get's more transprent as you decrease the value of MarkerFaceAlpha

here with MarkerFaceAlpha = 0.5

% Load the data
Image = imread('cameraman.tif');
% Display the original image
imshow(Image);
hold on;

% add some scatter dots wit transparency management
Ndots = 50;
[m,n] = size(Image);
X = randi([round(0.1*n),round(0.8*n)],Ndots,1);
Y = randi([round(0.1*m),round(0.8*m)],Ndots,1);
Z = 256*rand(Ndots,1);
durS = 256*rand(Ndots,1);
ps = scatter(X,Y,durS,Z,'filled','MarkerFaceAlpha',1);
colorbar

hold off