how to create image from text file data.?

http://speedy.sh/yCYux/patil142.txt

This is the text file i have generated.. I want to create image from it.. It will be binary image..

clc;

clear;

fileID = fopen('patil142.txt');

C = textscan(fileID, '%f32 %f32');

fclose(fileID);

x=cell2mat(C(:,1));

y=cell2mat(C(:,2));

x=x';

y=y';

I am able to read it only but don't know how to create image..?

[Walter Roberson]

How many pixels high and how many pixels wide do you want the image to be? What interval in "x" should a change of 1 pixel represent? What interval in "y" should a change of 1 pixel represent?

Note: some of your y values end in 0.5 so you need to be specific about how you want to handle that situation.

[Lalit Patil]

I want 1:480 rows and 1:720 columns.. every row and column changes at 1 pixel as given in text file.. 0.5 pixels will be taken as round(0.5) = 1

[Walter Roberson]

The text file you linked to has x running 1 to 480, but y in the range 333 to 340, and has no 0's in it. If you are hitting 0 then either there is a problem in the reading or you are reading different data than you linked to.

[Lalit Patil]

http://speedy.sh/cdEqJ/patil113.txt

sorry, i forget to upload new text file that contains 0's at somewhere..

scatter(x,y) shows plot and i want image. and the second column contains pixel intensities, so, 0 means nothing will be showed in image..

only positive integer values will be shown in image..

Answer 1

[Image Analyst]

Try this:

maxRows = max(y);
maxCols = max(x);
binaryImage = false(maxRows, maxCols);
for k = 1 : length(x)
  row = int32(y);
  col = int32(x);
  binaryImage(row, col) = true;
end

[Walter Roberson]

The loop is not necessary if you are not going to take into account fractions in the input.

binaryImage = accumarray( fix([x(:), y(:)]), true, [], [], false );

[Lalit Patil]

http://speedy.sh/Vr3K4/patil113.txt

Image Analyst, But this code doesn't work for this file as it contains some values 0. ??? Subscript indices must either be real positive integers or logicals. It shows this kind of error.

[Image Analyst]

Why do you have zeros? I guess your x and y are not pixel coordinates then. So just add 1 to all values:

% Start with 1 instead of 0.
x = x + 1;
y = y + 1;

Walter - nice addition. accumarray is one of those functions I never use and am not familiar with, though maybe I should be.

[Lalit Patil]

Yes, adding 1 it gives solution..

http://speedy.sh/G6mGU/Image113.jpg

This is the image.. patil113 contains its peak data.. Here in this image white pixels are 20pixels wide, and text file contains its peak and it is 1 pixel wide, so image should look like single pixel vertical strip... After adding 1 i am getting three full line strips..

[Image Analyst]

But what you posted is NOT a binary image - it's a gray scale image. So for each x,y coordinate you'd need to have a gray level, and your text file does not have that so there's no way for you to get the gray scale image like you posted.

[Walter Roberson]

What do you get if you

scatter(x,y)

[Lalit Patil]

http://speedy.sh/G6mRU/images113.jpg I am getting this kind of image using scatter(x,y) But it is a plot and i want image which will be saved later..

[Lalit Patil]

Yes, the image i posted is gray scale, but whatever the text file data is, it is after thresholding.. and text file data contains peaks of thresholdede image, and i verified it using ruler.. The ruler is attached here..

http://speedy.sh/FHUpX/JRuler.exe

[Image Analyst]

I'm not sure what the problem is. The image and the scatterplot both accurately reflect the numbers in your text file. So what's wrong? If there's something wrong, then it must be with how you got the numbers you wrote into the text file. If they are wrong then of course the image will be wrong also since the image is just the numbers in the text file.

[Walter Roberson]

Adjustment to my earlier code:

binaryImage = logical(accumarray( fix([x(:), y(:)]), 1, [480 720]) );

This has been tested with the data file you provided. The result is not really one line, but the changes in value are small enough that unless you zoom in you cannot really see the jags.

scatter() on the data does not look like what you show, not even if you reverse x and y: instead it looks like a continuous line at that scale. In particular, the data file has no 0's in it.

I copied and pasted your textscan() so as to be sure that I was reading exactly the same way as you are.

[Lalit Patil]

clc;

clear;

fileID = fopen('patil113.txt');

C = textscan(fileID, '%f32 %f32');

fclose(fileID);

x=cell2mat(C(:,1));

y=cell2mat(C(:,2));

x=x';

y=y';

binaryImage = logical(accumarray( fix([x(:), y(:)]), 1, [480 720]) );

imshow(binaryImage)

Yes, this works for me for text file which doesn't contains any zeros,

original image is

http://speedy.sh/wzuVf/Image142.jpg

Its text file pixel data is

http://speedy.sh/8EMp2/patil142.txt

The result i got is

http://speedy.sh/d3Dg9/142.jpg

. . .

But this doesn't work for

Original image

http://speedy.sh/gktSE/Image113.jpg

Its text file is

http://speedy.sh/FHU5X/patil113.txt

As it contains zeros and shows error...

[Walter Roberson]

What do you want to have happen where there are zeros? Put something in the left margin?

binaryImage = logical(accumarray( fix([x(:), 1+y(:)]), 1, [480 720]) );

or skip that row?

nz = y ~= 0;
x = x(nz);
y = y(nz);
binaryImage = logical(accumarray( ceil([x(:), y(:)]), 1, [480 720]) );

[Lalit Patil]

Yes this is the thing which i want.. Now the problem get solved...

[Walter Roberson]

Which version? The one that skipped those rows?