Stretching an ellipse in an image to form a circle

I want to stretch an elliptical object in an image until it forms a circle. My program currently inputs an image with an elliptical object (eg. coin at an angle), thresholds and binarizes it, isolates the region of interest using edge-detect/bwboundaries(), and performs regionprops() to calculate major/minor axis lengths.

Essentially, I want to use the 'MajorAxisLength' as the diameter and stretch the object on the minor axis to form a circle. Any suggestions on how I should approach this would be greatly appreciated. I have appended some code for your perusal (the binarized image looks like a white ellipse on a black background).

code snippet:

    rgbImage = imread(fullFileName);
    redChannel = rgbImage(:,:,1);
    binaryImage = redChannel < 90;
    labeledImage = bwlabel(binaryImage);
    area_measurements = regionprops(labeledImage,'Area');
    allAreas = [area_measurements.Area];
    biggestBlobIndex = find(allAreas == max(allAreas));
    keeperBlobsImage = ismember(labeledImage, biggestBlobIndex);
    measurements = regionprops(keeperBlobsImage,'Area','MajorAxisLength','MinorAxisLength')