# Find the actual distances in an image.

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Chathu on 15 Apr 2016
Commented: Chathu on 30 Apr 2016
I want to find the minimum x(1) value which touches the image,A. Then maximum x(2) value which touches the image,A.(ps:image is attached). I made the axis ON. SO i want to let the program identify the x(min), x(max),y(min) and y(max), next draw straight lines(as shown in the image) along above said points(eg:x(1),x(2),etc) and then perform the spatial calibration (note; image is not symmetric). Can anyone give me a hint how to resolve this issue.
##### 2 CommentsShowHide 1 older comment
Chathu on 15 Apr 2016
it is an image. Let me add it here now. Sorry for the confusion.

Mohammad Abouali on 15 Apr 2016
Similar approach to this should work:
thresh = 15;
mask = ~(I(:,:,1) < thresh & I(:,:,2) < thresh & I(:,:,1) < thresh);
xMin = find(xProj,1,'first')-0.5;
xMax = find(xProj,1,'last');
yMin = find(yProj,1,'first');
yMax = find(yProj,1,'last');
imshow(I);
hold on
plot([xMin xMin],ylim,'r','LineWidth',2)
plot([xMax xMax],ylim,'r','LineWidth',2)
plot(xlim,[yMin yMin],'r','LineWidth',2)
plot(xlim,[yMax yMax],'r','LineWidth',2) Chathu on 30 Apr 2016
@ Mohammad, i saw your response just now. Your approach is perfect for my purpose, as it is short distance.
Thank you so much for your response. Highly appreciate it:)

Image Analyst on 16 Apr 2016
See my spatial calibration demo.
Chathu on 16 Apr 2016
Thank you so much Image Analyst. Highly appreciated.