How can I change the color of a grid?

Dear users,

I'm intending to draw a grid on a image for point count using the command:

Ig2(50:50:end,:,:) = 0;

Ig2(:,50:50:end,:) = 0;

imshow(Ig2);

Over the image a black grid is draw. How do I change the color of the grid to yellow or red?

BR,

Answer 1

[Daniel]

If I were to check the size of your image matrix Ig2 I would see that

 size(Ig2)

returns

 x y c

Where x is the number of row in your matrix.

Where y is the number of columns in your matrix

Where c is of value 3 because you need to specify the intensity of Red, Green, Blue for each pixel.

So for any pixel that is at row 'i' and column 'j' I can choose the colour by changing the intensity of Red, Green and Blue in the following way:

 Ig2(i,j,1) = 1; %Set red to full intensity
 Ig2(i,j,2) = 0; %Set green to zero intensity
 Ig2(i,j,3) = 0; %Set blue to zero intensity

Now the pixel at location i,j will be red.

Back to your problem. To get a red grid all you need to do is the following:

 Ig2(50:50:end,:,1) = 1;
 Ig2(50:50:end,:,2) = 0;
 Ig2(50:50:end,:,3) = 0;

 Ig2(:,50:50:end,1) = 1;
 Ig2(:,50:50:end,2) = 0;
 Ig2(:,50:50:end,3) = 0;
 imshow(Ig2);

Play with the values on the right hand side to get different colours. Hint: to get yellow you have to mix red and green.

Answer 2

[Lori Lewis]

set(gca, 'Color', 'r')