Hi Devendra,
Based on my understanding, you want to generate an ENVI header file using MATLAB function ‘custom_ enviwrite’. To achieve this, you can go through the following steps and the attached code snippets:
1. Extract and format the 'map_info' and 'projection_info' strings from the data to match the ENVI header requirements.
% Construct the coordinate_information struct
map_info = 'UTM, 1.000, 1.000, 699960.000, 3300000.000, 20.000000, 20.000000, 43, North, WGS-84, units=Meters';
projection_info = 'PROJCS["WGS_1984_UTM_Zone_43N",GEOGCS["GCS_WGS_1984",DATUM["D_WGS_1984",SPHEROID["WGS_1984",6378137.0,298.257223563]],PRIMEM["Greenwich",0.0],UNIT["Degree",0.0174532925199433]],PROJECTION["Transverse_Mercator"],PARAMETER["False_Easting",500000.0],PARAMETER["False_Northing",0.0],PARAMETER["Central_Meridian",75.0],PARAMETER["Scale_Factor",0.9996],PARAMETER["Latitude_Of_Origin",0.0],UNIT["Meter",1.0]]';
2. Organize the data by creating structures for coordinate and wavelength data.
% Coordinate information structure
coordinate_information.map_info = map_info_str;
coordinate_information.projection_info = projection_info_str;
% Wavelength data
wavelength_data = [560.0, 665.0, 705.0, 740.0, 783.0, 842.0, 865.0];
3. Implement the ‘custom_enviwrite’ function validating the inputs to match the expected formats and convert images to suitable formats if necessary. Then write the image to a binary file and create a ENVI header file.
function custom_enviwrite(image, fname, coordinate_information, wavelength_data)
img = single(image);
cl = class(img);
data_types = [4, 1, 2, 3, 12, 13];
t = data_types(strcmp({'single', 'int8', 'int16', 'int32', 'uint16', 'uint32'}, cl));
wfid = fopen(fname, 'w');
fwrite(wfid, img, cl);
fclose(wfid);
fid = fopen([fname '.hdr'], 'w');
fprintf(fid, 'ENVI\n');
fprintf(fid, 'description = {Exported from MATLAB}\n');
fprintf(fid, 'samples = %i\n', size(image, 2));
fprintf(fid, 'lines = %i\n', size(image, 1));
fprintf(fid, 'bands = %i\n', size(image, 3));
fprintf(fid, 'data type = %i\n', t);
fprintf(fid, 'interleave = bsq\n');
fprintf(fid, 'map info = {%s}\n', coordinate_information.map_info);
fprintf(fid, 'projection info = {%s}\n', coordinate_information.projection_info);
fprintf(fid, 'wavelength units = Nanometers\n');
fprintf(fid, 'wavelength = {\n%.2f', wavelength_data(1));
for j = 2:length(wavelength_data)
fprintf(fid, ', %.2f', wavelength_data(j));
end
fprintf(fid, '}\n');
fclose(fid);
end
4. Generate the ENVI files by executing the function to create the files.
fname = 'output_image';
custom_enviwrite(image_data, fname, coordinate_information, wavelength_data);
To know more about the ‘strcmp’ or ’class’ functions in MATLAB, you can refer the following documentations:
- https://www.mathworks.com/help/matlab/ref/strcmp.html
- https://www.mathworks.com/help/matlab/ref/class.html
Hope this helps!
