MATLAB: Save an image with a plot

Question

Hey, see if anyone can fix a problem I have. I add an example using the sample image 'cameraman.tif', the image of the real code is another one but to get an idea it works perfectly.

I need to highlight the detected outline, so what I came up with was to get the pixel coordinates and represent them on top of the image by saying that these points are thicker.

Also, I make a crop of the image and I need to show in the original image the crop rectangle used.

When I save it, I want the highlighted pixels to look white and the square to look any other color, for example red.

Do you have any ideas on how to make the image as tight as possible so that the white pixels look white and not black?

Translated with www.DeepL.com/Translator (free version)

I = imread('cameraman.tif');
BW = edge(I,'canny');
[J,rect2] = imcrop(BW);
[r,c] = find ( BW == 1 );
pP = [c r];
f = figure;
imshow(I)
hold on
plot(pP(:,1),pP(:,2),'.w','MarkerSize',5)
rectangle('Position',rect2,'EdgeColor','red','LineWidth',3)
print('TH.tif','-dtiff')

What i want to obtain

Best Answer

Try this

I = imread('cameraman.tif');
BW = edge(I,'canny');
[J,rect2] = imcrop(BW);
[r,c] = find ( BW == 1 );
pP = [c r];
f = figure;
ax = axes;
imshow(I)
hold on
plot(pP(:,1),pP(:,2),'.w','MarkerSize',5)
rectangle('Position',rect2,'EdgeColor','red','LineWidth',3)
frame = getframe(gca);
imwrite(frame.cdata, 'TH.tif')

If you are using R2020a, then MATLAB also introduced exportgraphics

I = imread('cameraman.tif');
BW = edge(I,'canny');
[J,rect2] = imcrop(BW);
[r,c] = find ( BW == 1 );
pP = [c r];
f = figure;
ax = axes;
imshow(I)
hold on
plot(pP(:,1),pP(:,2),'.w','MarkerSize',5)
rectangle('Position',rect2,'EdgeColor','red','LineWidth',3)
exportgraphics(gca,'TH.tif')

Related Solutions

MATLAB: How to find the centroid of an object in an image and crop a portion of it around that centre point

I = imread('image.jpeg') ;
[nx,ny,nt] = size(I) ;
x = 1:ny ; y = 1:nx ;
C = round([mean(x) mean(y)]) ;
idx = C(2)-227:C(2)+227 ;
idy = C(1)-227:C(1)+227 ;
I = I(idx,idy,:) ;
imshow(I)

YOu may play around with idx and idy

MATLAB: How to calculate the curvature of a boundaries in binary images

Use bwboundaries to get a list of the (x,y) boundary coordinates. Run around that border taking a section of the curve, say 9 elements, and fit a polynomial to it. Knowing the derivative of the curve model you used, and the coefficients polyfit() gave you, you can get the curvature at each point. Then run around the list of (x,y) edge coordinates using a marker color that corresponds to the curvature. Try to program that up. If you can't do it all , then post what you have and I'll try to help with the rest.

Related Question

• How to smooth / refine edges ?
• How to produce edge detected image
• How to draw a filled circle
• How to extract connected chains in canny edge image? Specifically asking, how would I extract connected chains when there are so many edges are available, so that I could come up with top 10 results (top 10 long edges).
• Issue with getframe and getimage commands while saving the image (image size mismatch).

Answer 1

Try this

I = imread('cameraman.tif');
BW = edge(I,'canny');
[J,rect2] = imcrop(BW);
[r,c] = find ( BW == 1 );
pP = [c r];
f = figure;
ax = axes;
imshow(I)
hold on
plot(pP(:,1),pP(:,2),'.w','MarkerSize',5)
rectangle('Position',rect2,'EdgeColor','red','LineWidth',3)
frame = getframe(gca);
imwrite(frame.cdata, 'TH.tif')

If you are using R2020a, then MATLAB also introduced exportgraphics

I = imread('cameraman.tif');
BW = edge(I,'canny');
[J,rect2] = imcrop(BW);
[r,c] = find ( BW == 1 );
pP = [c r];
f = figure;
ax = axes;
imshow(I)
hold on
plot(pP(:,1),pP(:,2),'.w','MarkerSize',5)
rectangle('Position',rect2,'EdgeColor','red','LineWidth',3)
exportgraphics(gca,'TH.tif')