MATLAB Function Reference

multibandwrite

Write multiband data to file

Syntax

• multibandwrite(data,filename,interleave)
  multibandwrite(data,filename,interleave,start,totalsize)
  multibandwrite(...,param,value,...)
  

Description

multibandwrite(data,filename,interleave) writes data, a two- or three-dimensional numeric or logical array, to the binary file specified by filename. The length of the third dimension of data determines the number of bands written to the file. The bands are written to the file in the form specified by interleave. See Interleave Methods for more information about this argument.

If filename already exists, multibandwrite overwrites it unless you specify the optional offset parameter. See the last alternate syntax for multibandwrite for information about other optional parameters.

multibandwrite(data,filename,interleave,start,totalsize) writes data to the binary file filename in chunks. In this syntax, data is a subset of the complete data set.

start is a 1-by-3 array [firstrow firstcolumn firstband] that specifies the location to start writing data. firstrow and firstcolumn specify the location of the upper left image pixel. firstband gives the index of the first band to write. For example, data(I,J,K) contains the data for the pixel at [firstrow+I-1, firstcolumn+J-1] in the (firstband+K-1)-th band.

totalsize is a 1-by-3 array, [totalrows,totalcolumns,totalbands], which specifies the full, three-dimensional size of the data to be written to the file.

Note    In this syntax, you must call multibandwrite multiple times to write all the data to the file. The first time it is called, multibandwrite writes the complete file, using the fill value for all values outside the data subset. In each subsequent call, multibandwrite overwrites these fill values with the data subset in data. The parameters filename, interleave, offset, and totalsize must remain constant throughout the writing of the file.

multibandwrite(...,param,value...) writes the multiband data to a file, specifying any of these optional parameter/value pairs.

Parameter	Description
'precision'	String specifying the form and size of each element written to the file. See the help for fwrite for a list of valid values. The default precision is the class of the data.
'offset'	The number of bytes to skip before the first data element. If the file does not already exist, multibandwrite writes ASCII null values to fill the space. To specify a different fill value, use the parameter 'fillvalue'. This option is useful when you are writing a header to the file before or after writing the data. When writing the header to the file after the data is written, open the file with fopen using 'r+' permission.
machfmt	String to control the format in which the data is written to the file. Typical values are 'ieee-le' for little endian and 'ieee-be' for big endian. See the help for fopen for a complete list of available formats. The default machine format is the local machine format.
fillvalue	A number specifying the value to use in place of missing data. 'fillvalue' can be a single number, specifying the fill value for all missing data, or a 1-by-Number-of-bands vector of numbers specifying the fill value for each band. This value is used to fill space when data is written in chunks.

Interleave Methods

interleave is a string that specifies how multibandwrite interleaves the bands as it writes data to the file. If data is two-dimensional, multibandwrite ignores the interleave argument. The following table lists the supported methods and uses this example multiband file to illustrate each method.

Supported methods of interleaving bands include those listed below.

Method	String	Description	Example
Band-Interleaved-by-Line	'bil'	Write an entire row from each band	AAAAABBBBBCCCCC AAAAABBBBBCCCCC AAAAABBBBBCCCCC
Band-Interleaved-by-Pixel	'bip'	Write a pixel from each band	ABCABCABCABCABC...
Band-Sequential	'bsq'	Write each band in its entirety	AAAAA AAAAA AAAAA BBBBB BBBBB BBBBB CCCCC CCCCC CCCCC

Examples

In this example, all the data is written to the file with one function call. The bands are interleaved by line.

• multibandwrite(data,'data.img','bil');
  

This example uses multibandwrite in a loop to write each band to a file separately.

• for i=1:totalBands
     multibandwrite(bandData,'data.img','bip',[1 1 i],...
     [totalColumns, totalRows, totalBands]);
  end
  

In this example, only a subset of each band is available for each call to multibandwrite. For example, an entire data set can have three bands with 1024-by-1024 pixels each (a 1024-by-1024-by-3 matrix). Only 128-by-128 chunks are available to be written to the file with each call to multibandwrite.

• numBands = 3;
  totalDataSize =  [1024 1024 numBands];
  for i=1:numBands
     for k=1:8
         for j=1:8
            upperLeft = [(k-1)*128 (j-1)*128 i];
            multibandwrite(data,'banddata.img','bsq',...
                           upperLeft,totalDataSize);
         end
     end
  end
  

See Also

multibandread, fwrite, fread

multibandread

munlock

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