Loop in a array

Hi,

I have a question. I have an image with three bands. How can I apply a loop for do an operation to all the pixels?

image1=imread('image_1.tif'); %I've load the image. Has a length of 4x4x3
band1a= image_1(:,:,1);
band2a= image_1( :,:,2);
band3b= image_1(:,:,3);

for i = 1:numel(band1b)

(...) this is the part of the operation

output= ?

Thanks a lot in advance,

[Sabarinathan Vadivelu]

Which operation u have to perform on all the pixels?

[Emmanuelle]

Thanks for your reply Sabarinathan. It's an interpolation...

for i = 1:numel(band1b) 
for i = 1:numel(banda2b)
... 
and then inter= interp1(l1,l2,t2,'spline'))

...on the same pixel on the three bands and then, an operation of multiply for other variable to obtain one result.

oper1= b1abc.*interplan;
output1= sum(oper1);

And the output1 is the result for the operation.

[Jan]

Please post a running piece of code. In the original question, "band1b" is not defined and we cannot guess its value. In the comment "l1, l2, t2, interplan, b1abc" is not defined.

Usually interpolations can be performed for a full vector or even a matrix directly without a loop.

[Emmanuelle]

I know it would be a bit confusing...

   image1=imread('image_1.tif'); 
   band1a= image1(:,:,1);
   band2a= image1(:,:,2);
   band3b= image1(:,:,3);

   for i = 1:numel(band1b) 
   ma = zeros(100,1);
   ma(10) = banda1b(i);
   end 
  for i = 1:numel(band2b)
   ma(25) = banda2b(i);
   end 
  for i = 1:numel(band3b)
   ma(50) = band3b(i);
   end 

vec1= [10, 25, 50]';
 pos1= ma(10);
 pos2= ma(25);
 pos3= ma(50);
 vec2= [pos1 pos2 pos3];
 t= 0:100;
 xi= 0:1:100;
 interplan= interp1(vec1,vec2,t,'spline');

   sp1_a= spb1y.*interplan; %I've defined sp1by before
   sp1_b= sp1_a./spsum1;
   sp2_a= spb2y.*interplan;
   sp2_b= sp2_a./spsum2;
   sp3_a= spb3y.*interplan;
   sp3_b= spout3_a./spsum3;

    spout1_c= sum(spout1_b);
   spout2_c= sum(spout1_b);
   spout3_c= sum(spout1_b);

I know it could be something confusing but what I want is to get this last three values (spout1_c, spout2_c and spout3_c) for every pixel, in every band.

Hope I've explain this well!

[Emmanuelle]

The main problem is the following part because in an assignment A(I) = B, the number of elements in B must be the same but, I need to do it because it's important the 'position' in the interpolation.

   for i = 1:numel(band1b) 
   ma = zeros(100,1);
   ma(10) = banda1b(i);
   end 
  for i = 1:numel(band2b)
   ma(25) = banda2b(i);
   end 
  for i = 1:numel(band3b)
   ma(50) = band3b(i);
   end

Answer 1

[Image Analyst]

What is image_1? All you have shown up until that point is image1, which is a different variable.

[Emmanuelle]

Yes, you are right! It's the image.

    image1=imread('image_1.tif'); 
     band1a= image1(:,:,1);
     band2a= image1(:,:,2);
     band3b= image1(:,:,3);

[Image Analyst]

Regarding "I know it could be something confusing but what I want is to get this last three values (spout1_c, spout2_c and spout3_c) for every pixel, in every band." How about this:

image1(:, :, 1) = spout1_a;
image1(:, :, 2) = spout1_b;
image1(:, :, 3) = spout1_c;

[Emmanuelle]

Thanks Image analyst! :) I've solved the problem starting the code like this:

for row= 1: nrows
      for col= 1: ncols
        for band= 1: nband

But now I don't know how it's possible to copy correctly the output. I've created my output matrix like this:

output= zeros(1200, 1202, 3);

And I want to copy the spout1_a to the first band (band1a), spout1_b to the second.... I'm trying with that but I get the following error: " Conversion to double from cell is not possible."

output(:,:,1)= {spout1_c}

Thanks!!