How to Detect Shape in Image MATLAB

I want to Detect the shape in image

I have the following two image in one image i have Normal Shape and in second image i have shape with noise

im_002317.png

im_002017.png

I have the following code which works well on im_002317.png as shown in untitled.png attached.

But when i added Noise to that line the values changes as in image im_002017.png

The shape is not detected well.

How can i modified the code to detect the same shape

Or How can i draw bounding box on each level to detect the whole shape

rgbImage = imread('Noise\im_002017.png');
[rows, columns, numberOfColorChannels] = size(rgbImage);
if numberOfColorChannels > 1
	grayImage = rgbImage(:, :, 3);
else
	grayImage = rgbImage;
end
mask = grayImage >= 128;
[labeledImage, numRegions] = bwlabel(mask);
props = regionprops(labeledImage, 'Area', 'Centroid','BoundingBox');
allLengths = [props.Area];
NumberofPulses=allLengths;
centroids = vertcat(props.Centroid);
whiteLineRows1 = centroids(:, 2);
DSPRFValue= unique(whiteLineRows1);
Levels=length(DSPRFValue);
figure;
hold on;
for k = 1 : numRegions
    y1 = centroids(k, 2);
    y2 = y1;
	xt = props(k).Centroid(1);
	yt = props(k).Centroid(2);
    BB = props(k).BoundingBox;
	str = sprintf('Pulse Length %d at PRF %d', allLengths(k), y1);
    xlim([0 1000]);
	text(xt, yt, str, 'Color', 'r',  'HorizontalAlignment', 'Center', 'VerticalAlignment','bottom', 'FontSize',8);
    rectangle('Position', [BB(1),BB(2),BB(3),BB(4)],'EdgeColor','b','LineWidth',1) ;
    PRFValue(k)=y1;
    caption = sprintf('Dwell and Swtich Image with %d Levels', Levels);
    hold off
    title(caption, 'FontSize',10);

[Med Future]

@Image Analyst