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R8218/private/parseimagesubheader20.m
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parseimagesubheader20.m
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function isnitf_meta = parseimagesubheader20( fid, dataLength )
%PARSEIMAGESUBHEADER Parse the Image subheaders in an NITF file.
% ISNITF_META = PARSEIMAGESUBHEADER
% Parse the Image Segment Subheader for an NITF 2.0 file.
% Copyright 2007-2008 The MathWorks, Inc.
% TODO: complete refactorization around conditionals
% Initialize the image subheader structure
isnitf_meta = struct([]);
fields = {'IM', 'FilePartType', 2
'IID', 'ImageID', 10
'IDATIM', 'ImageDateAndTime', 14
'TGTID', 'TargetID', 17
'ITITLE', 'ImageTitle', 80
'ISCLAS', 'ImageSecurityClassification', 1
'ISCODE', 'ImageCodewords', 40
'ISCTLH', 'ImageControlAndHandling', 40
'ISREL', 'ImageReleasingInstructions', 40
'ISCAUT', 'ImageClassificationAuthority', 20
'ISCTLN', 'ImageSecurityControlNumber', 20
'ISDWNG', 'ImageSecurityDowngrade', 6};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
%ISDWNG is the last item extracted in the loop above. Depending
%on its value there will be an ISDEVT or Image Downgrading Event field.
%If ISDWNG is "999998, add the ISDEVT field to the meta data struct
%and insert values.
isdwng = sscanf(isnitf_meta(end).value, '%f');
%File downgrade event is conditional on fsdwng
isnitf_meta = checkISDWNG(fid, isnitf_meta, isdwng);
fields = {'ENCRYP', 'Encryption', 1
'ISORCE', 'ImageSource', 42
'NROWS', 'NumberOfSignificantRowsInImage', 8
'NCOLS', 'NumberOfSignificantColumnsInImage', 8
'PVTYPE', 'PixelValueType', 3
'IREP', 'ImageRepresentation', 8
'ICAT', 'ImageCategory', 8
'ABPP', 'ActualBitsPerPixelPerBand', 2
'PJUST', 'PixelJustification', 1
'ICORDS', 'ImageCoordinateSystem', 1};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
%ICORDS Depending on its value there will be an IGEOLO or Image Geographic Location field.
%If ICORDS is not a space, add the IGEOLO field to the meta data struct
%and insert values.
icords = isnitf_meta(end).value;
isnitf_meta = checkIcords(icords, fid, isnitf_meta);
%NICOM
%Depending on its value there will be ICOM fields (ICOM1 through ICOMn).
%If NICOM is not zero, add the comment fields to the meta data struct
%and insert their values.
fields = {'NICOM', 'NumberOfImageComments', 1};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
nicom = sscanf(isnitf_meta(end).value, '%f');
isnitf_meta = checkNicom(nicom, fid, isnitf_meta);
%Next field is Image Compression
fields = {'IC', 'ImageCompression', 2};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
%Next field is COMRAT or Compression Rate Code
%If the IC field is not NC or NM the field will have a value.
ic = isnitf_meta(end).value;
if ~strcmp(ic, 'NC') && ~strcmp(ic, 'NM')
fields = {'COMRAT', 'CompressionRateCode', 4};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
end
fields = {'NBANDS', 'NumberOfBands', 1};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
bands = sscanf(isnitf_meta(end).value, '%f');
%Set up Band substructure
isnitf_meta(end + 1).name = 'Band Meta';
isnitf_meta(end).vname = 'BandMeta';
%The value will be a structure of band data
%The next seven fields occur for each band as indicated by BANDS
% Lengths:
% IREPBAND 2, ISUBCAT 6, IFC 1, IMFLT 3, NLUTS 1, NELUT 5 [omitted if NLUTS = 0]
% LUTD contains data for the mth LUT of the nnth band
nitf_metaBand(bands).value = '';
for currentBand = 1: bands
isBandnitf_meta = struct([]);
nitf_metaBand(currentBand).name = sprintf('Band%03d', currentBand);
nitf_metaBand(currentBand).vname = [nitf_metaBand(currentBand).name 'Meta'];
nitf_metaBand(currentBand).value = '';
fields = {'IREPBAND%02d', 'BandRepresentation%02d', 2
'ISUBCAT%02d', 'BandSubcategory%02d', 6
'IFC%02d', 'BandImageFilterCondition%02d', 1
'IMFLT%02d', 'BandImageFilterCode%02d', 3
'NLUTS%02d', 'BandNumberOfLUTS%02d', 1};
isBandnitf_meta = nitfReadMetaMulti(isBandnitf_meta, fields, fid, currentBand);
numluts = sscanf(isBandnitf_meta(end).value, '%f');
if numluts ~= 0
%nnth Band Number of LUT Entries
fields = {'NELUT%02d', 'BandNumberOfLUTEntries%02d', 5};
isBandnitf_meta = nitfReadMetaMulti(isBandnitf_meta, fields, fid, currentBand);
numlutentries = sscanf(isBandnitf_meta(end).value', '%f');
%The value will be a struct of LUT data
for currentLut = 1 : numluts
isBandnitf_meta(end + 1).name = sprintf('LUTData%1d', currentLut);
isBandnitf_meta(end).vname = sprintf('LUTData%1d', currentLut);
% Note: not converted to char.
isBandnitf_meta(end).value = fread(fid, numlutentries, 'uint8');
end
end
nitf_metaBand(currentBand).value = isBandnitf_meta;
end
isnitf_meta(end).value = nitf_metaBand;
fields = {'ISYNC', 'ImageSyncCode', 1
'IMODE', 'ImageMode' 1
'NBPR', 'NumberOfBlocksPerRow', 4
'NBPC', 'NumberOfBlocksPerColumn', 4
'NPPBH', 'NumberOfPixelsPerBlockHorizontal', 4
'NPPBV', 'NumberOfPixelsPerBlockVertical', 4
'NBPP', 'NumberOfBitsPerPixelPerBand', 2
'IDLVL', 'DisplayLevel', 3
'IALVL', 'ImageAttachmentLevel', 3
'ILOC', 'ImageLocation', 10
'IMAG', 'ImageMagnification', 4};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
% The IMAG value should be converted to a number from the decimal string.
isnitf_meta(end).value = sscanf(isnitf_meta(end).value, '%f');
fields = {'UDIDL', 'UserDefinedImageDataLength', 5};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
%If UDIDL is not zeros we'll have values for UDOFL and UDID
UDIDL = sscanf(isnitf_meta(end).value, '%f');
if UDIDL ~= 0
fields = {'UDOFL', 'UserDefinedOverflow', 3
'UDID', 'UserDefinedImageData', UDIDL - 3};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
end
fields = {'IXSHDL', 'ExtendedSubheaderDataLength', 5};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
%If IXSHDL is not zeros we'll have values for IXSOFL and IXSHD
IXSHDL = sscanf(isnitf_meta(end).value, '%f');
if IXSHDL ~= 0
fields = {'IXOFL', 'ExtendedSubheaderOverflow', 3
'IXSHD', 'ExtendedSubheaderData', IXSHDL - 3};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
end
%Move the cursor through the image data
readforwardbytes = sscanf(dataLength, '%f');
fseek(fid, readforwardbytes, 'cof');
function isnitf_meta = checkISDWNG(fid, isnitf_meta, fsdwng)
if fsdwng == 999998
fields = {'ISDEVT', 'ImageDowngradingEvent', 40};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
end
function isnitf_meta = checkIcords(icords, fid, isnitf_meta)
if ~strcmp(icords, 'N')
fields = {'IGEOLO', 'ImageGeographicLocation', 60};
isnitf_meta = nitfReadMeta(isnitf_meta, fields, fid);
end
function isnitf_meta = checkNicom(nicom, fid, isnitf_meta)
% Parse the Image Comment fields in the image subheader
% The length of the ICOM field is 80.
for currentComment = 1:nicom
%Pull the Image Comment
fields = {'ICOM%1d', 'ImageComment%1d', 80};
isnitf_meta = nitfReadMetaMulti(isnitf_meta, fields, fid, currentComment);
end
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