How to plot values in a grid manner so as to form an image?

2013 5 1
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I am writing a function which read data from a file having the following dimension [105 1 107]. Now I want to plot the data(which is in the form of a single column] in a manner such that it creates an image with dimensions [105 X 107]. I have written the following function, but all I get is a blue image, whereas I should get an image with different colors based on the values present at x,y co-ordinate in the mzSpecificData. Can anyone please let me know what is going wrong?
[x,temp,y]=size(mzSpecificData)
for yLoop = 1:y
for xLoop = 1:x
image(mzSpecificData(xLoop,temp,yLoop))
end
end
here; max value of x = 105, value of temp = 1 (which is a single constant value) max value of y = 107

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Image Analyst
Image Analyst 2013-5-1
What does this mean: "plot the data(which is in the form of a single column] in a manner such that it creates an image with dimensions [105 X 107]" Do you want to plot the values of one of the 107 columns as a line chart, or do you want to take that y-z plane of your image and display it as a 2D gray scale image? What you said is ambiguous. What do you want to do: plot or display?
Novice Geek
Novice Geek 2013-5-6
Here I wish to "display" my data in the form a 2D image which has the dimensions [105 X 107]. Thats the reason why I used the xLoop and the yLoop which which ask as co-ordinates (xLoop,yLoop) to display data in the form of a color at a specific co-ordinate. I hope I am able to make the problem understood. Thank you

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Image Analyst
Image Analyst 2013-5-6

1 个投票

Purva: Your image has 1 for the second dimension (the x or column dimension). That means that it is basically a slice in the y-z plane, with the column being 1 because you have only 1 for that dimension. You can use squeeze to turn this y-z plane into a normal, ordinary grayscale image. You can then display the image as a whole by using image() or imshow().
What your code did was to extract out just one pixel - the pixel at row = xLoop, column = 1, and z=yLoop - and then display just this one single pixel as the whole image. So I'm sure you didn't see anything except just one single square of one intensity, which is just the one pixel.
I hope that explains it better. To see your image you should be able to just do
grayImage = squeeze(mzSpecificData);
imshow(grayImage, []);
There is no loop or anything anymore - that is the entire code.

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Anand
Anand 2013-5-1

1 个投票

Try this:
im = squeeze(mzSpecificData);
image(im); %or imshow(im);

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Novice Geek
Novice Geek 2013-5-6
This is not working for the above function. Should I use
im = squeeze(mzSpecificData);
within the loop or outside?
Image Analyst
Image Analyst 2013-5-6
I don't think you'd have a loop. Certainly not the one you had were you were displaying just a single pixel!
Novice Geek
Novice Geek 2013-5-6
I know that the loop which I have applied is working I checked and found that the value at a specific co-ordinate (xLoop,yLoop) is correct as well. I now just need to display all these values in an image form. This is where I am stuck.
Novice Geek
Novice Geek 2013-5-6
But, without a loop how would the function take the next value/ or go to the next co-ordinate. When I used imshow(), I got an image with one pixel after iterating through both the loop 105 X 107 times. Is the image for every pixel overlapping the previous one?

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