how to color circles on an image? the color should varies with the variation of the serial data

i have a microcontroller connected to a force sensor and sending serial data. i'm putting these data in a matrix i need to draw circles to represent the force sensors on an image and color them the color should varies with the values of the serial data. example if the value in the matrix is 46 the color of the circle should varies from blue to red could someone help me please

Answer 1

[William Frane]

A simple way to do this is to plot large circular data markers on top of the image (using the hold command). Something along the lines of:

% Display image
hold on
% Iterate through all the sensors
% Get position and color for each sensor
currentColor = ConvertValueToColor(currentSensorValue);
plot(currentX, currentY, 'Marker', 'o', 'MarkerSize', 30, 'MarkerFaceColor', currentColor, 'MarkerEdgeColor', 'none');

If you normalize your sensor data such that they lie between 0 and 1, you could use something like this to vary the color:

function out = ConvertValueToColor(in) % Picks a color between blue and red
% Assumes 'in' is between 0 and 1
out = (1-in)*[0 0 1] + in*[1 0 0];

Answer 2

[Image Analyst]

Another way is to use the rectangle() function to draw circles. Kind of crazy, but yes, rectangle() can draw circles(). I've always wondered why they just don't have a ellipse() or circle() function. But no, that would be too easy and intuitive.

Answer 3

[marc kahwaji]

thanks for your help