How to find row and column of a pixel in an Image?

Guys I want to find the rows and columns of pixels of image so that i can put that in if condition inside for loop. Bt i am unable to write that code. plz help me.

[Camilo Andrés Roca Duarte]

I think you first have to clarify a litle your question, because you can use the coman [row,col]=find(variable==#) to find the pixel you want once you have the matrix of the pixel ( if it is not in truecolor). If you know the color of the pixel you just have to find the number that represent it in a scale (for instance 256 colors). I give this lines of a code I wrote recently to find the pixels in an images that are not totally white (in a scale of 256 colors.

[row,col]=find(Imagen~=255);

[Radha r]

how do find image row and coloumn pixel in matrix in train image because i would geetting the good and bad pixel find out

[Image Analyst]

Radha r, Start your own question and post your image and explain what "good" and "bad" means to you.

Answer 1

[Wolfgang Schwanghart]

Hi, what about this:

[ROWS,COLUMNS] = ndgrid(1:size(I,1),1:size(I,2));

ROWS = ROWS(:);
COLUMNS = COLUMNS(:);

where I is your image.

Best regards, Wolfgang

[Radha r]

but how do find good and bad pixel in image

Answer 2

[Karan Ratnaparkhi]

Hi wolfgang I have an algorithm in which i am given a range of rows n columns lets say a to b (for rows) and c to d (for columns). now I hav to do operation only on those pixels which lie (whose rows n cols lie) in between a to b and c to d. Thats y i want to know how to get the row and column of given pixel (not the value of pixel.) Plz help me with this code.

[Wolfgang Schwanghart]

This sounds to me as if you want to perform some calculations within a subset of your image. Without knowing what exactly you want to do there, I suggest to take a look at the roi-based image processing section of the documentation.

http://www.mathworks.com/help/toolbox/images/ref/roifilt2.html

HTH, Wolfgang

[Karan Ratnaparkhi]

hey thnx wolfgang...

Answer 3

[Syed Ali Hassan]

Check this [row_limit,col_limit]=size(img);

[Image Analyst]

A bit risky and dangerous in general. See http://blogs.mathworks.com/steve/2011/03/22/too-much-information-about-the-size-function/ - Steve's blog. Unless you know for a fact in advance that the image is gray scale, you'll be safer and more robust if you do this:

% This works for grayscale and RGB images:
[rows, columns, numberOfColorChannels] = size(yourImage);

[Radha r]

 it is not find the t my answer and what are you telling me i ont now please tell me example

[Radha r]

plz help me sir

Answer 4

[Radha r]

it is not find the t my answer and what are you telling me i ont now please tell me example

[Image Analyst]

Radha r, Start your own question and post your image and explain what "good" and "bad" means to you.