How to Read or access diagonal pixels of an Image from (R1,C1) to (R2,C2)?

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AMAR P
AMAR P el 19 de Sept. de 2018
Comentada: Saurabh Patel el 21 de Sept. de 2018
Following is the image am working on. * it's more of splitting an image in sort-of-45degree.* I have taken a random samples along ROW and COLUMNS.
SelectRowSample = 1 112 223 334 445 555
SelectColSample = 1 141 281 421 561 700
  • 1st Blue line start from (141,1) and should end on (1,112).
  • 2nd from (281,1) and should end on (1,223).and onwards.
ImageSize = 555x700
what I have tried?
for ColNum = 1:AllSampleCols
RowElem = 1;
for ColElem = SelectColSample(ColNum):-1:1
text(ColElem,RowElem,'.','Color','b');
if (RowElem < SelectRowSample(ColNum))
RowElem = RowElem + 1;
end
end
end
  1 comentario
AMAR P
AMAR P el 21 de Sept. de 2018
Answer/Solution:
  • Get Co-Ords of the Points that you wish to join.
  • Calculate length of a every line segment.
  • Calculate absolute Co-Ords of the each pixel using linspace.
  • Use X and y Co-ords to draw Plot.

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Respuestas (1)

Saurabh Patel
Saurabh Patel el 20 de Sept. de 2018
Try the following:
% Specify the value of (r1,c1) and (r2,c2)
r1 = 1; c1 = 112;
r2 = 141; c2 = 1;
% alpha is parameter used to reach from point 1 to point 2
alpha = (0:0.1:1)';
% (r,c) are the points on the line
r = round(r1+alpha*(r2-r1));
c = round(c1+alpha*(c2-c1));
% extracting the image intensity at (r,c)
index = sub2ind(size(I),r,c);
selectedI = I(index);
% Check if this is what you desire
figure(), hold on
imagesc(I)
plot(c,r)
  2 comentarios
AMAR P
AMAR P el 21 de Sept. de 2018
I think this can work. Will give it a try. What do you think about using.
linspace()
instead of
r = round(r1+alpha*(r2-r1));
c = round(c1+alpha*(c2-c1));
Saurabh Patel
Saurabh Patel el 21 de Sept. de 2018
Yes, you can use linspace(). It essentially does the same. The reason I used parametric form is to keep it clear that we are getting the image coordinates of the pixels lying on the line (the r and c expressed here as typical parametric form of a line).

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