Finding particular R, G, B value by comparing with threshold and fetching its corresponding pixel locations from table

I have a 20*3 rgbvalues matrix of an image

and given below table cx and cy are its corresponding pixel locations

and now i want to check in the rgbvalues table which satisfying the following condition,

((R>=0 && R<=100) && (G>=0 && G<=100) &&(B>=0 && B<=100)) and the corresponding cx and cy pixel location values. can anybody help me?

Answer 1

[Image Analyst]

Try this:

mask = (R>=0 & R<=100) & (G>=0 & G<=100) & (B>=0 & B<=100);
cxInMask = cx(mask);
cyInMask = cy(mask);

Take special note that I am using only single ampersands, not double ones because I want to do operations on a logical vector.

For your data, like Jan said, both will be empty since no row satisfies your criteria.

[meenu v]

Sry sir, it was a typing mistake. The condition was like ((R>=0 && R<=100) && (G>=0 && G<=100) && (B>=0 && B<=255));

Have one doubt, by using single ampersands, checks only one condition? I want to check all the conditions like (R>=0 && R<=100) && (G>=0 && G<=100) && (B>=0 && B<=100). How can be make it possible?

[Image Analyst]

No, using a single ampersand will create a binary image - a mask image.

"How can be make it possible?" I already showed you. Just do what I said. Don't change it back to what you said which will make it not work again. Make adjustments to the values if you want but don't change the ampersands to double ampersands.

[meenu v]

k..thnku

Answer 2

[Jan]

None of the colors in the table satisfies B <= 100. What ever the relation between the two tables is and whatever "corresponding cx and cy pixel location" means, while no element of B is matching, the condition is false in every case.

This solution seems to be trivial. Therefore I guess, you meant something else. Then please explain it again.

Answer 3

[meenu v]

Some part of the code is given

pq =impixel(Original_Img(:,:,1:3), cxInMask,cyInMask);   
 R=pq(:,1);
 G=pq (:,2);
 B=pq (:,3);

if ((x (1) > 58 && x (1) <  200) && (y(1) >  401 && y(1) <  650))
  if ((R>=0 && R<=250)&&(G>=0 && G<=50)&&(B>=0 && B<=255))
    disp ('The content is very low in this region.');
  elseif ((R>=0 && R<=190)&&(G>=0 && G<=90)&&(B>=250 && B<=255))
    disp ('The content is high in this region.');
  end
end

R, G, B vector obtained will be like the one shown in above question. The values will change in every exceution .

Running the code produces an error like,

• _Operands to the and && operators must be convertible to logical scalar values.

Error in Untitled (line 25) If ((R>=0 && R<=250)&&(G>=0 && G<=1)&&(B>=0 && B<=255))

_ * How to resolve this error?

[Image Analyst]

If you'd look in the workspace, you'd see that you never defined an x and y. Plus R, G, and B are most likely full images, not single values so you should be using single ampersands like I've told you already, or if you want the R, G, and B at a single point then you should index them or use the pq variable you created.

[meenu v]

this is not what i meant to ask. i will start a new question for that. Thank u....