How can I write 32-bit floating point TIFs with NaNs?

10 Mag 2011
1 Risposta
Risposta accettata
Aggiornato 24 Mag 2019
19 Visualizzazioni (30 giorni)

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I'm able to use IMREAD to read 32-bit floating point TIFs with NaNs for dead pixels.
After this, I do an image rotation with IMTRANSFORM with 'FillValue' of NaN (IMROTATE only fills with zeros).
Now, I'd like to save 32-bit floating point TIFs with NaNs in tact for later.
How can I do this? I've tried IMWRITE and MULTIBANDWRITE, but they don't seem to work.
I'm using MATLAB 7.11.0 (R2010b).
Thanks,
Kevin Crosby

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Walter Roberson
Walter Roberson il 10 Mag 2011
Modificato: Walter Roberson il 27 Feb 2015

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I suggest using the Tiff class and specifying RGB for the Photometric and specifying 32 bits per channel and writing single precision values.
http://www.mathworks.com/help/matlab/ref/tiff-class.html
This is based upon the assumption that you want the channel values themselves to be NaN, rather than setting the Alpha value to be NaN for the dead pixels.

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Kevin Crosby
Kevin Crosby il 10 Mag 2011
Thanks for the prompt response. I'm trying to implement this now.
Kevin Crosby
Kevin Crosby il 10 Mag 2011
Modificato: Walter Roberson il 24 Mag 2019
I changed Photometric to MinIsBlack, since I'm dealing with grayscale images. You are correct that the pixels values themselves are NaN.
Assuming that I overwrite my original file in variable "filename" with the transformed image in "timg", here's the relevant code ...
info = imfinfo(filename);
t = Tiff(filename, 'w');
tagstruct.ImageLength = size(timg, 1);
tagstruct.ImageWidth = size(timg, 2);
tagstruct.Compression = Tiff.Compression.None;
tagstruct.SampleFormat = Tiff.SampleFormat.IEEEFP;
tagstruct.Photometric = Tiff.Photometric.MinIsBlack;
tagstruct.BitsPerSample = info.BitsPerSample; % 32;
tagstruct.SamplesPerPixel = info.SamplesPerPixel; % 1;
tagstruct.PlanarConfiguration = Tiff.PlanarConfiguration.Chunky;
t.setTag(tagstruct);
t.write(timg);
t.close();
Thanks again!
Chris Volpe
Chris Volpe il 24 Mag 2019
I've tried this, but it's converting my 32-bit float data to 8 BPP grayscale for some reason. My data is range data, specified in millimeters as a single precision float. I've tried both MinIsBlack and LinearRaw for the Photometric option, but no luck. Any thoughts?
Here's my code:
t = Tiff(fullfile(filepath, [basename '.tif']), 'w');
tagstruct.ImageLength = size(depthImage, 1);
tagstruct.ImageWidth = size(depthImage, 2);
tagstruct.Compression = Tiff.Compression.None;
tagstruct.SampleFormat = Tiff.SampleFormat.IEEEFP;
tagstruct.Photometric = Tiff.Photometric.LinearRaw;
tagstruct.BitsPerSample = 32;
tagstruct.SamplesPerPixel = 1;
tagstruct.PlanarConfiguration = Tiff.PlanarConfiguration.Chunky;
t.setTag(tagstruct);
t.write(single(depthImage));
t.close();
Walter Roberson
Walter Roberson il 24 Mag 2019
I just re-tested the code I posted at https://www.mathworks.com/matlabcentral/answers/307519-image-file-saved-using-tiff-library-tif-appear-white-in-explorer-and-paintbrush#answer_239772 and confirm that it creates single precision on my Mac in R2019a. The only difference I can see is the Photometric.

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