Saving indexed tif images from for loop: Problem with file size.
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Hi, I have the following loop that takes a 32-bit 4D data set data(m,n,i,j) and outputs i*j indexed m by n images.
fid=fopen('myfile','rb','ieee-le');
data4D=fread(fid,'int32');
image_dir=pwd;
for i=1:size(data4D,3)
for k=1:size(data4D,4)
data3D=squeeze(abs(data4D(:,:,1:1:end,k)));
data2D=(mat2gray(squeeze(data3D(:,:,i))));
baseFileName = strcat( 'Image_', num2str(k) ...
, 'SubImage_', num2str(i),'.tif');
fullFileName = fullfile(image_dir,baseFileName);
imwrite(data2D, fullFileName);
end
end
This saves the images, but they are not the correct file size, or bit number. I have tried to use the Tiff function to save the images, but I must not be doing it incorrectly, because the images are saved, but they all look 100% black. Is there a Matlab master out there who can tune up this script?
Thanks?
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Answers (1)
Image Analyst
on 21 Nov 2014
I don't think TIFF can take pixels in the range 0-1. Well maybe it can with special options. But you're calling mat2gray so why not simply multiply it by 255 and cast to uint8?
data2D= uint8(255*mat2gray(squeeze(data3D(:,:,i))));
9 Comments
Image Analyst
on 25 Nov 2014
Please answer my question about the original range of the data. It may well be that the upper bytes are not being used.
You say your code "takes a 32-bit 4D data set data(m,n,i,j)". What is the data type of "data"? Is it int32, uint32, or single? It's not double like you said above if it's only 32 bits. Double is 8 bytes or 64 bits.
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