Error reading raw int16 FITS file with fitsread

The command, "KAF = fitsread(fnami2);" imports the fits file data. However, the command,

"KAF=fitsread(fnami2,'raw');" returns the errors:

Error in matlab.io.fits.readImg (line 85)

imgdata = matlab.internal.imagesci.fitsiolib('read_subset',fptr,fpixel,lpixel,inc);

Error in fitsread>read_image_hdu (line 449)

data = fits.readImg(fptr);

Error in fitsread (line 140)

data = read_image_hdu(info,1,raw,pixelRegion);

Error in Read_KAF2 (line 27)

KAF=fitsread(fnami2,'raw');

The fits file is [3056, 3056] uint16 data that we want to use as raw digital numbers without the default scaling.

Thank you for any assisstance you may provide.

Answer 1

[Nikhil]

Hi Robert,

You maybe getting this error due to different version of MATLAB.

Check this page for reference: https://in.mathworks.com/help/matlab/ref/fitsread.html

Or try this:

% Obtain information about the FITS file
info = fitsinfo(fnami2);

% Get the primary HDU (Header Data Unit) index
primaryHDU = info.PrimaryData.Key;

% Open the FITS file
fitsFile = fits.openFile(fnami2);

% Read the image data from the primary HDU as raw digital numbers
imageData = fits.readImg(fitsFile, primaryHDU);

% Close the FITS file
fits.closeFile(fitsFile);

% Assign the data to the variable KAF
KAF = imageData;

[Robert Farley]

Hi Nikhil,

Thanks for the answer, but info.PrimaryData.Key doesn't exist so that command returns an error. There is an info.PrimaryData.Keywords structure with the following variables:

Field Value

imfo.PrimaryData.Keywords 'int16'

imfo.PrimaryData.Offset [3056,3056]

imfo.PrimaryData.Slope 18678272

imfo.PrimaryData.Intercept [ ]

imfo.PrimaryData.MissingDataValue 32768

imfo.PrimaryData.DataSize 1

imfo.PrimaryData.Size 5760

imfo.PrimaryData.DataType 39x3 cell

I read the fitsread.html webpage that indicates KAF=fitsread(fnami2,'raw'); should work.

Thanks for trying, but the only command provided to read raw fits data appears not to work.