Position Of pixel

heyy.. can anyone help me out in finding out the position of pixel of an binaryimage and the grayscale value of pixel

 Accepted Answer

Sean de Wolski
Sean de Wolski on 19 May 2011
Igray(Ibinary); %extract gray values of true binary values
true_locations = find(Ibinary); %indices of binary values
You'll have to be more specific if you want more information.
EDIT per comment/clarification:
%Ibinary is your logical map
%Igray is your grayscale image
%Conversions as necessary
if ~isa(Igray,'double');Igray = double(Igray);end
if ~islogical(Ibinary);Ibinary = logical(Ibinary);end
wtrr = bsxfun(@times,(1:size(Igray,1)).',Igray); %weighted Igray by rows
wtrr = sum(wtrr(Ibinary)); %Sum the ones that matter
wtcc = bsxfun(@times,1:size(Igray,2),Igray); %weighted Igray by columns
wtcc = sum(wtcc(Ibinary)); %sum the ones that matter
Gtot = sum(Igray(:));
CGr = sum(wtrr(:))/Gtot;
CGc = sum(wtcc(:))/Gtot;
%CGr is the CG amongst rows (y) and CGc is the CG amongst columns (x)

7 Comments

Gova ReDDy
Gova ReDDy on 19 May 2011
danx for ur reply....ill give a detail information abt dis...
I want to find the position of centre of gravity of binary image using the formual:
COG=(summation(position of pixel * grayscale value of pixel) ) %(summation (grayscale value of pixel))...is der anyother way to find out COG
Gova ReDDy
Gova ReDDy on 20 May 2011
In this line % wtrr = bsxfun(@times,(1:size(Igray,1)).',Igray) %
what does % (1:size(Igray,1)).',Igray) % means
Gova ReDDy
Gova ReDDy on 20 May 2011
what dis %logical % does
Sean de Wolski
Sean de Wolski on 20 May 2011
It multiplies element-wise the column vector (1:size(Igray,1)).' by every column of Igray. logical converts an image to binary.
doc logical
doc bsxfun
Gova ReDDy
Gova ReDDy on 20 May 2011
Danxxxxxxx...can u please figure out this one
How to prepare images of the Gaussian shaped illumination intensity line with --half width:20 lenght:1200 tilt:0.001
Sean de Wolski
Sean de Wolski on 20 May 2011
Nope.
Gova ReDDy
Gova ReDDy on 20 May 2011
thanks in advance....can u xplain me what %gauss2mf% function does in detail

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