//File input = ...
//InputStream input = ...
//byte[] input = ...
//ByteReader input = ...

TIFFImage tiffImage = TiffReader.readTiff(input);
List<FileDirectory> directories = tiffImage.getFileDirectories();
FileDirectory directory = directories.get(0);
Rasters rasters = directory.readRasters();

int width = 256;
int height = 256;
int samplesPerPixel = 1;
FieldType fieldType = FieldType.FLOAT;
int bitsPerSample = fieldType.getBits();

Rasters rasters = new Rasters(width, height, samplesPerPixel,
		fieldType);

int rowsPerStrip = rasters.calculateRowsPerStrip(
		TiffConstants.PLANAR_CONFIGURATION_CHUNKY);

FileDirectory directory = new FileDirectory();
directory.setImageWidth(width);
directory.setImageHeight(height);
directory.setBitsPerSample(bitsPerSample);
directory.setCompression(TiffConstants.COMPRESSION_NO);
directory.setPhotometricInterpretation(
		TiffConstants.PHOTOMETRIC_INTERPRETATION_BLACK_IS_ZERO);
directory.setSamplesPerPixel(samplesPerPixel);
directory.setRowsPerStrip(rowsPerStrip);
directory.setPlanarConfiguration(
		TiffConstants.PLANAR_CONFIGURATION_CHUNKY);
directory.setSampleFormat(TiffConstants.SAMPLE_FORMAT_FLOAT);
directory.setWriteRasters(rasters);

for (int y = 0; y < height; y++) {
	for (int x = 0; x < width; x++) {
		float pixelValue = 1.0f; // any pixel value
		rasters.setFirstPixelSample(x, y, pixelValue);
	}
}

TIFFImage tiffImage = new TIFFImage();
tiffImage.add(directory);
byte[] bytes = TiffWriter.writeTiffToBytes(tiffImage);
// or
// File file = ...
// TiffWriter.writeTiff(file, tiffImage);