manipulating multipage TIFF file

I have a geo-refenreced TIFF file with 14 pages corresponding to 14 wavelengths. I want to normalize the image at each wavelength and create a new TIFF file with the normalized images. So far no problem. My problem is that the first page in my original TIFF includes a field called "GPSInfo" that I need to pass along to the new TIFF file. Imwrite does not seem to support the inclusion of such information in a TIFF file. Any suggestions?

Thanks

Answer 1

[Dheeraj]

Hi,

Writing custom metadata like "GPSInfo" you can use a combination of functions from the MATLAB File Exchange and the built-in functions as "imwrite" does not support the inclusion of such information in a TIFF file.

1. Use the "imread" function to read the original TIFF file and extract the first page's "GPSInfo" metadata using a library like the "Tiff" class.
2. Apply the necessary normalization
3. Use the imwrite function to create a new TIFF file for the normalized images.
4. After writing each normalized image to the new TIFF file, use a custom function to add the "GPSInfo" metadata to the first page of the new TIFF file.

for i = 1:14 %Iterating through all pages
   % Create a new file with normalised images, let it be newNormalisedPage
   % Add "GPSInfo" metadata to the first page of the new TIFF file
   if i == 1
       new_tiff = Tiff( newNormalisedPage , 'r+');
       new_tiff.setTag('GPSInfo', gps_info);
       new_tiff.close();
   end
end

Also refer to https://in.mathworks.com/help/matlab/ref/imwrite.html?searchHighlight=imwrite&s_tid=srchtitle_support_results_1_imwrite for better understanding of imwrite capabilities.

[Raphael]

I would like to follow-up on this as this answer does not seem to work for me. I have an image with 14 bands which I write to a tif file as shown below.

t2w=uint16(rand(201,207,14)); % dummy image in same format as actual one
[r,c,w]=size(t2w);
 t = Tiff('myrandfile.tif','w');  
setTag(t,'Photometric',1)
 setTag(t,'PlanarConfiguration',1)
setTag(t,'ImageLength',r)
setTag(t,'ImageWidth',c)
setTag(t,'BitsPerSample',16);
setTag(t,'Compression',1);
setTag(t,'SamplesPerPixel',14);
setTag(t,"ExtraSamples",Tiff.ExtraSamples.Unspecified)
write(t,t2w)

Warning: Sum of Photometric color channels and ExtraSamples does not match the value specified in SamplesPerPixel.
Writing with this configuration will error in a future release. To correct the configuration, define the non-color channels as ExtraSamples.

close(t)

(BTW, can somone explain how to get rid of this warining?). Despite this warning message the tiff file is created correctly for my needs.

When I try to add a new tag as suggested in the answer above I get an error message:

new_tiff=Tiff('myrandfile.tif','r+');

Warning: TIFF library warning - 'TIFFReadDirectory: Sum of Photometric type-related color channels and ExtraSamples doesn't match SamplesPerPixel. Defining non-color channels as ExtraSamples..'

new_tiff.setTag('GPSInfo','MyInfo');

Error using Tiff/setTagInFile (line 2559)
'GPSInfo' is not a recognized tag name.

Error in Tiff/setTag (line 1412)
obj.setTagInFile(varargin{:});