src/main/java/org/apache/commons/imaging/formats/pnm/PnmImageParser.java - commons-imaging - Git at Google

 /*
  * Licensed to the Apache Software Foundation (ASF) under one or more
  * contributor license agreements.  See the NOTICE file distributed with
  * this work for additional information regarding copyright ownership.
  * The ASF licenses this file to You under the Apache License, Version 2.0
  * (the "License"); you may not use this file except in compliance with
  * the License.  You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */
 package org.apache.commons.imaging.formats.pnm;

 import java.awt.Dimension;
 import java.awt.image.BufferedImage;
 import java.io.File;
 import java.io.IOException;
 import java.io.InputStream;
 import java.io.OutputStream;
 import java.io.PrintWriter;
 import java.util.ArrayList;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
 import java.util.StringTokenizer;

 import org.apache.commons.imaging.ImageFormat;
 import org.apache.commons.imaging.ImageFormats;
 import org.apache.commons.imaging.ImageInfo;
 import org.apache.commons.imaging.ImageParser;
 import org.apache.commons.imaging.ImageReadException;
 import org.apache.commons.imaging.ImageWriteException;
 import org.apache.commons.imaging.common.ByteOrder;
 import org.apache.commons.imaging.common.IImageMetadata;
 import org.apache.commons.imaging.common.ImageBuilder;
 import org.apache.commons.imaging.common.bytesource.ByteSource;
 import org.apache.commons.imaging.palette.PaletteFactory;
 import org.apache.commons.imaging.util.IoUtils;

 public class PnmImageParser extends ImageParser implements PnmConstants {

     public PnmImageParser() {
         super.setByteOrder(ByteOrder.LITTLE_ENDIAN);
         // setDebug(true);
     }

     @Override
     public String getName() {
         return "Pbm-Custom";
     }

     @Override
     public String getDefaultExtension() {
         return DEFAULT_EXTENSION;
     }

     private static final String DEFAULT_EXTENSION = ".pnm";

     private static final String ACCEPTED_EXTENSIONS[] = { ".pbm", ".pgm",
             ".ppm", ".pnm", ".pam" };

     @Override
     protected String[] getAcceptedExtensions() {
         return ACCEPTED_EXTENSIONS;
     }

     @Override
     protected ImageFormat[] getAcceptedTypes() {
         return new ImageFormat[] {
                 ImageFormats.PBM, //
                 ImageFormats.PGM, //
                 ImageFormats.PPM, //
                 ImageFormats.PNM,
                 ImageFormats.PAM
         };
     }

     private FileInfo readHeader(final InputStream is) throws ImageReadException,
             IOException {
         final byte identifier1 = readByte("Identifier1", is, "Not a Valid PNM File");
         final byte identifier2 = readByte("Identifier2", is, "Not a Valid PNM File");

         if (identifier1 != PNM_PREFIX_BYTE) {
             throw new ImageReadException("PNM file has invalid prefix byte 1");
         }

         final WhiteSpaceReader wsr = new WhiteSpaceReader(is);

         if (identifier2 == PBM_TEXT_CODE ||
                 identifier2 == PBM_RAW_CODE ||
                 identifier2 == PGM_TEXT_CODE ||
                 identifier2 == PGM_RAW_CODE ||
                 identifier2 == PPM_TEXT_CODE ||
                 identifier2 == PPM_RAW_CODE) {

             final int width = Integer.parseInt(wsr.readtoWhiteSpace());
             final int height = Integer.parseInt(wsr.readtoWhiteSpace());

             if (identifier2 == PBM_TEXT_CODE) {
                 return new PbmFileInfo(width, height, false);
             } else if (identifier2 == PBM_RAW_CODE) {
                 return new PbmFileInfo(width, height, true);
             } else if (identifier2 == PGM_TEXT_CODE) {
                 final int maxgray = Integer.parseInt(wsr.readtoWhiteSpace());
                 return new PgmFileInfo(width, height, false, maxgray);
             } else if (identifier2 == PGM_RAW_CODE) {
                 final int maxgray = Integer.parseInt(wsr.readtoWhiteSpace());
                 return new PgmFileInfo(width, height, true, maxgray);
             } else if (identifier2 == PPM_TEXT_CODE) {
                 final int max = Integer.parseInt(wsr.readtoWhiteSpace());
                 return new PpmFileInfo(width, height, false, max);
             } else if (identifier2 == PPM_RAW_CODE) {
                 final int max = Integer.parseInt(wsr.readtoWhiteSpace());
                 return new PpmFileInfo(width, height, true, max);
             } else {
                 throw new ImageReadException("PNM file has invalid header.");
             }
         } else if (identifier2 == PAM_RAW_CODE) {
             int width = -1;
             boolean seenWidth = false;
             int height = -1;
             boolean seenHeight = false;
             int depth = -1;
             boolean seenDepth = false;
             int maxVal = -1;
             boolean seenMaxVal = false;
             String tupleType = "";
             boolean seenTupleType = false;

             // Advance to next line
             wsr.readLine();
             String line;
             while ((line = wsr.readLine()) != null) {
                 line = line.trim();
                 if (line.startsWith("#")) {
                     continue;
                 }
                 final StringTokenizer tokenizer = new StringTokenizer(line, " ", false);
                 final String type = tokenizer.nextToken();
                 if (type.equals("WIDTH")) {
                     seenWidth = true;
                     width = Integer.parseInt(tokenizer.nextToken());
                 } else if (type.equals("HEIGHT")) {
                     seenHeight = true;
                     height = Integer.parseInt(tokenizer.nextToken());
                 } else if (type.equals("DEPTH")) {
                     seenDepth = true;
                     depth = Integer.parseInt(tokenizer.nextToken());
                 } else if (type.equals("MAXVAL")) {
                     seenMaxVal = true;
                     maxVal = Integer.parseInt(tokenizer.nextToken());
                 } else if (type.equals("TUPLTYPE")) {
                     seenTupleType = true;
                     tupleType += tokenizer.nextToken();
                 } else if (type.equals("ENDHDR")) {
                     break;
                 } else {
                     throw new ImageReadException("Invalid PAM file header type " + type);
                 }
             }

             if (!seenWidth) {
                 throw new ImageReadException("PAM header has no WIDTH");
             } else if (!seenHeight) {
                 throw new ImageReadException("PAM header has no HEIGHT");
             } else if (!seenDepth) {
                 throw new ImageReadException("PAM header has no DEPTH");
             } else if (!seenMaxVal) {
                 throw new ImageReadException("PAM header has no MAXVAL");
             } else if (!seenTupleType) {
                 throw new ImageReadException("PAM header has no TUPLTYPE");
             }

             return new PamFileInfo(width, height, depth, maxVal, tupleType);
         } else {
             throw new ImageReadException("PNM file has invalid prefix byte 2");
         }
     }

     private FileInfo readHeader(final ByteSource byteSource)
             throws ImageReadException, IOException {
         InputStream is = null;
         boolean canThrow = false;
         try {
             is = byteSource.getInputStream();

             final FileInfo ret = readHeader(is);
             canThrow = true;
             return ret;
         } finally {
             IoUtils.closeQuietly(canThrow, is);
         }
     }

     @Override
     public byte[] getICCProfileBytes(final ByteSource byteSource, final Map<String,Object> params)
             throws ImageReadException, IOException {
         return null;
     }

     @Override
     public Dimension getImageSize(final ByteSource byteSource, final Map<String,Object> params)
             throws ImageReadException, IOException {
         final FileInfo info = readHeader(byteSource);

         if (info == null) {
             throw new ImageReadException("PNM: Couldn't read Header");
         }

         return new Dimension(info.width, info.height);
     }

     public byte[] embedICCProfile(final byte image[], final byte profile[]) {
         return null;
     }

     @Override
     public boolean embedICCProfile(final File src, final File dst, final byte profile[]) {
         return false;
     }

     @Override
     public IImageMetadata getMetadata(final ByteSource byteSource, final Map<String,Object> params)
             throws ImageReadException, IOException {
         return null;
     }

     @Override
     public ImageInfo getImageInfo(final ByteSource byteSource, final Map<String,Object> params)
             throws ImageReadException, IOException {
         final FileInfo info = readHeader(byteSource);

         if (info == null) {
             throw new ImageReadException("PNM: Couldn't read Header");
         }

         final List<String> Comments = new ArrayList<String>();

         final int BitsPerPixel = info.getBitDepth() * info.getNumComponents();
         final ImageFormat Format = info.getImageType();
         final String FormatName = info.getImageTypeDescription();
         final String MimeType = info.getMIMEType();
         final int NumberOfImages = 1;
         final boolean isProgressive = false;

         // boolean isProgressive = (fPNGChunkIHDR.InterlaceMethod != 0);
         //
         final int PhysicalWidthDpi = 72;
         final float PhysicalWidthInch = (float) ((double) info.width / (double) PhysicalWidthDpi);
         final int PhysicalHeightDpi = 72;
         final float PhysicalHeightInch = (float) ((double) info.height / (double) PhysicalHeightDpi);

         final String FormatDetails = info.getImageTypeDescription();

         final boolean isTransparent = info.hasAlpha();
         final boolean usesPalette = false;

         final int ColorType = info.getColorType();
         final String compressionAlgorithm = ImageInfo.COMPRESSION_ALGORITHM_NONE;

         final ImageInfo result = new ImageInfo(FormatDetails, BitsPerPixel, Comments,
                 Format, FormatName, info.height, MimeType, NumberOfImages,
                 PhysicalHeightDpi, PhysicalHeightInch, PhysicalWidthDpi,
                 PhysicalWidthInch, info.width, isProgressive, isTransparent,
                 usesPalette, ColorType, compressionAlgorithm);

         return result;
     }

     @Override
     public boolean dumpImageFile(final PrintWriter pw, final ByteSource byteSource)
             throws ImageReadException, IOException {
         pw.println("pnm.dumpImageFile");

         final ImageInfo imageData = getImageInfo(byteSource);
         if (imageData == null) {
             return false;
         }

         imageData.toString(pw, "");

         pw.println("");

         return true;
     }

     @Override
     public BufferedImage getBufferedImage(final ByteSource byteSource, final Map<String,Object> params)
             throws ImageReadException, IOException {
         InputStream is = null;
         boolean canThrow = false;
         try {
             is = byteSource.getInputStream();

             final FileInfo info = readHeader(is);

             final int width = info.width;
             final int height = info.height;

             final boolean hasAlpha = info.hasAlpha();
             final ImageBuilder imageBuilder = new ImageBuilder(width, height,
                     hasAlpha);
             info.readImage(imageBuilder, is);

             final BufferedImage ret = imageBuilder.getBufferedImage();
             canThrow = true;
             return ret;
         } finally {
             IoUtils.closeQuietly(canThrow, is);
         }
     }

     public static final String PARAM_KEY_PNM_RAWBITS = "PNM_RAWBITS";
     public static final String PARAM_VALUE_PNM_RAWBITS_YES = "YES";
     public static final String PARAM_VALUE_PNM_RAWBITS_NO = "NO";

     @Override
     public void writeImage(final BufferedImage src, final OutputStream os, Map<String,Object> params)
             throws ImageWriteException, IOException {
         PnmWriter writer = null;
         boolean useRawbits = true;
         final boolean hasAlpha = new PaletteFactory().hasTransparency(src);

         if (params != null) {
             final Object useRawbitsParam = params.get(PARAM_KEY_PNM_RAWBITS);
             if (useRawbitsParam != null) {
                 if (useRawbitsParam.equals(PARAM_VALUE_PNM_RAWBITS_NO)) {
                     useRawbits = false;
                 }
             }

             final Object subtype = params.get(PARAM_KEY_FORMAT);
             if (subtype != null) {
                 if (subtype.equals(ImageFormats.PBM)) {
                     writer = new PbmWriter(useRawbits);
                 } else if (subtype.equals(ImageFormats.PGM)) {
                     writer = new PgmWriter(useRawbits);
                 } else if (subtype.equals(ImageFormats.PPM)) {
                     writer = new PpmWriter(useRawbits);
                 } else if (subtype.equals(ImageFormats.PAM)) {
                     writer = new PamWriter();
                 }
             }
         }

         if (writer == null) {
             if (hasAlpha) {
                 writer = new PamWriter();
             } else {
                 writer = new PpmWriter(useRawbits);
             }
         }

         // make copy of params; we'll clear keys as we consume them.
         if (params != null) {
             params = new HashMap<String,Object>(params);
         } else {
             params = new HashMap<String,Object>();
         }

         // clear format key.
         if (params.containsKey(PARAM_KEY_FORMAT)) {
             params.remove(PARAM_KEY_FORMAT);
         }

         if (params.size() > 0) {
             final Object firstKey = params.keySet().iterator().next();
             throw new ImageWriteException("Unknown parameter: " + firstKey);
         }

         writer.writeImage(src, os, params);
     }

     /**
      * Extracts embedded XML metadata as XML string.
      * <p>
      *
      * @param byteSource
      *            File containing image data.
      * @param params
      *            Map of optional parameters, defined in ImagingConstants.
      * @return Xmp Xml as String, if present. Otherwise, returns null.
      */
     @Override
     public String getXmpXml(final ByteSource byteSource, final Map<String,Object> params)
             throws ImageReadException, IOException {
         return null;
     }
 }
	/*
	* Licensed to the Apache Software Foundation (ASF) under one or more
	* contributor license agreements. See the NOTICE file distributed with
	* this work for additional information regarding copyright ownership.
	* The ASF licenses this file to You under the Apache License, Version 2.0
	* (the "License"); you may not use this file except in compliance with
	* the License. You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/
	package org.apache.commons.imaging.formats.pnm;

	import java.awt.Dimension;
	import java.awt.image.BufferedImage;
	import java.io.File;
	import java.io.IOException;
	import java.io.InputStream;
	import java.io.OutputStream;
	import java.io.PrintWriter;
	import java.util.ArrayList;
	import java.util.HashMap;
	import java.util.List;
	import java.util.Map;
	import java.util.StringTokenizer;

	import org.apache.commons.imaging.ImageFormat;
	import org.apache.commons.imaging.ImageFormats;
	import org.apache.commons.imaging.ImageInfo;
	import org.apache.commons.imaging.ImageParser;
	import org.apache.commons.imaging.ImageReadException;
	import org.apache.commons.imaging.ImageWriteException;
	import org.apache.commons.imaging.common.ByteOrder;
	import org.apache.commons.imaging.common.IImageMetadata;
	import org.apache.commons.imaging.common.ImageBuilder;
	import org.apache.commons.imaging.common.bytesource.ByteSource;
	import org.apache.commons.imaging.palette.PaletteFactory;
	import org.apache.commons.imaging.util.IoUtils;

	public class PnmImageParser extends ImageParser implements PnmConstants {

	public PnmImageParser() {
	super.setByteOrder(ByteOrder.LITTLE_ENDIAN);
	// setDebug(true);
	}

	@Override
	public String getName() {
	return "Pbm-Custom";
	}

	@Override
	public String getDefaultExtension() {
	return DEFAULT_EXTENSION;
	}

	private static final String DEFAULT_EXTENSION = ".pnm";

	private static final String ACCEPTED_EXTENSIONS[] = { ".pbm", ".pgm",
	".ppm", ".pnm", ".pam" };

	@Override
	protected String[] getAcceptedExtensions() {
	return ACCEPTED_EXTENSIONS;
	}

	@Override
	protected ImageFormat[] getAcceptedTypes() {
	return new ImageFormat[] {
	ImageFormats.PBM, //
	ImageFormats.PGM, //
	ImageFormats.PPM, //
	ImageFormats.PNM,
	ImageFormats.PAM
	};
	}

	private FileInfo readHeader(final InputStream is) throws ImageReadException,
	IOException {
	final byte identifier1 = readByte("Identifier1", is, "Not a Valid PNM File");
	final byte identifier2 = readByte("Identifier2", is, "Not a Valid PNM File");

	if (identifier1 != PNM_PREFIX_BYTE) {
	throw new ImageReadException("PNM file has invalid prefix byte 1");
	}

	final WhiteSpaceReader wsr = new WhiteSpaceReader(is);

	if (identifier2 == PBM_TEXT_CODE \|\|
	identifier2 == PBM_RAW_CODE \|\|
	identifier2 == PGM_TEXT_CODE \|\|
	identifier2 == PGM_RAW_CODE \|\|
	identifier2 == PPM_TEXT_CODE \|\|
	identifier2 == PPM_RAW_CODE) {

	final int width = Integer.parseInt(wsr.readtoWhiteSpace());
	final int height = Integer.parseInt(wsr.readtoWhiteSpace());

	if (identifier2 == PBM_TEXT_CODE) {
	return new PbmFileInfo(width, height, false);
	} else if (identifier2 == PBM_RAW_CODE) {
	return new PbmFileInfo(width, height, true);
	} else if (identifier2 == PGM_TEXT_CODE) {
	final int maxgray = Integer.parseInt(wsr.readtoWhiteSpace());
	return new PgmFileInfo(width, height, false, maxgray);
	} else if (identifier2 == PGM_RAW_CODE) {
	final int maxgray = Integer.parseInt(wsr.readtoWhiteSpace());
	return new PgmFileInfo(width, height, true, maxgray);
	} else if (identifier2 == PPM_TEXT_CODE) {
	final int max = Integer.parseInt(wsr.readtoWhiteSpace());
	return new PpmFileInfo(width, height, false, max);
	} else if (identifier2 == PPM_RAW_CODE) {
	final int max = Integer.parseInt(wsr.readtoWhiteSpace());
	return new PpmFileInfo(width, height, true, max);
	} else {
	throw new ImageReadException("PNM file has invalid header.");
	}
	} else if (identifier2 == PAM_RAW_CODE) {
	int width = -1;
	boolean seenWidth = false;
	int height = -1;
	boolean seenHeight = false;
	int depth = -1;
	boolean seenDepth = false;
	int maxVal = -1;
	boolean seenMaxVal = false;
	String tupleType = "";
	boolean seenTupleType = false;

	// Advance to next line
	wsr.readLine();
	String line;
	while ((line = wsr.readLine()) != null) {
	line = line.trim();
	if (line.startsWith("#")) {
	continue;
	}
	final StringTokenizer tokenizer = new StringTokenizer(line, " ", false);
	final String type = tokenizer.nextToken();
	if (type.equals("WIDTH")) {
	seenWidth = true;
	width = Integer.parseInt(tokenizer.nextToken());
	} else if (type.equals("HEIGHT")) {
	seenHeight = true;
	height = Integer.parseInt(tokenizer.nextToken());
	} else if (type.equals("DEPTH")) {
	seenDepth = true;
	depth = Integer.parseInt(tokenizer.nextToken());
	} else if (type.equals("MAXVAL")) {
	seenMaxVal = true;
	maxVal = Integer.parseInt(tokenizer.nextToken());
	} else if (type.equals("TUPLTYPE")) {
	seenTupleType = true;
	tupleType += tokenizer.nextToken();
	} else if (type.equals("ENDHDR")) {
	break;
	} else {
	throw new ImageReadException("Invalid PAM file header type " + type);
	}
	}

	if (!seenWidth) {
	throw new ImageReadException("PAM header has no WIDTH");
	} else if (!seenHeight) {
	throw new ImageReadException("PAM header has no HEIGHT");
	} else if (!seenDepth) {
	throw new ImageReadException("PAM header has no DEPTH");
	} else if (!seenMaxVal) {
	throw new ImageReadException("PAM header has no MAXVAL");
	} else if (!seenTupleType) {
	throw new ImageReadException("PAM header has no TUPLTYPE");
	}

	return new PamFileInfo(width, height, depth, maxVal, tupleType);
	} else {
	throw new ImageReadException("PNM file has invalid prefix byte 2");
	}
	}

	private FileInfo readHeader(final ByteSource byteSource)
	throws ImageReadException, IOException {
	InputStream is = null;
	boolean canThrow = false;
	try {
	is = byteSource.getInputStream();

	final FileInfo ret = readHeader(is);
	canThrow = true;
	return ret;
	} finally {
	IoUtils.closeQuietly(canThrow, is);
	}
	}

	@Override
	public byte[] getICCProfileBytes(final ByteSource byteSource, final Map<String,Object> params)
	throws ImageReadException, IOException {
	return null;
	}

	@Override
	public Dimension getImageSize(final ByteSource byteSource, final Map<String,Object> params)
	throws ImageReadException, IOException {
	final FileInfo info = readHeader(byteSource);

	if (info == null) {
	throw new ImageReadException("PNM: Couldn't read Header");
	}

	return new Dimension(info.width, info.height);
	}

	public byte[] embedICCProfile(final byte image[], final byte profile[]) {
	return null;
	}

	@Override
	public boolean embedICCProfile(final File src, final File dst, final byte profile[]) {
	return false;
	}

	@Override
	public IImageMetadata getMetadata(final ByteSource byteSource, final Map<String,Object> params)
	throws ImageReadException, IOException {
	return null;
	}

	@Override
	public ImageInfo getImageInfo(final ByteSource byteSource, final Map<String,Object> params)
	throws ImageReadException, IOException {
	final FileInfo info = readHeader(byteSource);

	if (info == null) {
	throw new ImageReadException("PNM: Couldn't read Header");
	}

	final List<String> Comments = new ArrayList<String>();

	final int BitsPerPixel = info.getBitDepth() * info.getNumComponents();
	final ImageFormat Format = info.getImageType();
	final String FormatName = info.getImageTypeDescription();
	final String MimeType = info.getMIMEType();
	final int NumberOfImages = 1;
	final boolean isProgressive = false;

	// boolean isProgressive = (fPNGChunkIHDR.InterlaceMethod != 0);
	//
	final int PhysicalWidthDpi = 72;
	final float PhysicalWidthInch = (float) ((double) info.width / (double) PhysicalWidthDpi);
	final int PhysicalHeightDpi = 72;
	final float PhysicalHeightInch = (float) ((double) info.height / (double) PhysicalHeightDpi);

	final String FormatDetails = info.getImageTypeDescription();

	final boolean isTransparent = info.hasAlpha();
	final boolean usesPalette = false;

	final int ColorType = info.getColorType();
	final String compressionAlgorithm = ImageInfo.COMPRESSION_ALGORITHM_NONE;

	final ImageInfo result = new ImageInfo(FormatDetails, BitsPerPixel, Comments,
	Format, FormatName, info.height, MimeType, NumberOfImages,
	PhysicalHeightDpi, PhysicalHeightInch, PhysicalWidthDpi,
	PhysicalWidthInch, info.width, isProgressive, isTransparent,
	usesPalette, ColorType, compressionAlgorithm);

	return result;
	}

	@Override
	public boolean dumpImageFile(final PrintWriter pw, final ByteSource byteSource)
	throws ImageReadException, IOException {
	pw.println("pnm.dumpImageFile");

	final ImageInfo imageData = getImageInfo(byteSource);
	if (imageData == null) {
	return false;
	}

	imageData.toString(pw, "");

	pw.println("");

	return true;
	}

	@Override
	public BufferedImage getBufferedImage(final ByteSource byteSource, final Map<String,Object> params)
	throws ImageReadException, IOException {
	InputStream is = null;
	boolean canThrow = false;
	try {
	is = byteSource.getInputStream();

	final FileInfo info = readHeader(is);

	final int width = info.width;
	final int height = info.height;

	final boolean hasAlpha = info.hasAlpha();
	final ImageBuilder imageBuilder = new ImageBuilder(width, height,
	hasAlpha);
	info.readImage(imageBuilder, is);

	final BufferedImage ret = imageBuilder.getBufferedImage();
	canThrow = true;
	return ret;
	} finally {
	IoUtils.closeQuietly(canThrow, is);
	}
	}

	public static final String PARAM_KEY_PNM_RAWBITS = "PNM_RAWBITS";
	public static final String PARAM_VALUE_PNM_RAWBITS_YES = "YES";
	public static final String PARAM_VALUE_PNM_RAWBITS_NO = "NO";

	@Override
	public void writeImage(final BufferedImage src, final OutputStream os, Map<String,Object> params)
	throws ImageWriteException, IOException {
	PnmWriter writer = null;
	boolean useRawbits = true;
	final boolean hasAlpha = new PaletteFactory().hasTransparency(src);

	if (params != null) {
	final Object useRawbitsParam = params.get(PARAM_KEY_PNM_RAWBITS);
	if (useRawbitsParam != null) {
	if (useRawbitsParam.equals(PARAM_VALUE_PNM_RAWBITS_NO)) {
	useRawbits = false;
	}
	}

	final Object subtype = params.get(PARAM_KEY_FORMAT);
	if (subtype != null) {
	if (subtype.equals(ImageFormats.PBM)) {
	writer = new PbmWriter(useRawbits);
	} else if (subtype.equals(ImageFormats.PGM)) {
	writer = new PgmWriter(useRawbits);
	} else if (subtype.equals(ImageFormats.PPM)) {
	writer = new PpmWriter(useRawbits);
	} else if (subtype.equals(ImageFormats.PAM)) {
	writer = new PamWriter();
	}
	}
	}

	if (writer == null) {
	if (hasAlpha) {
	writer = new PamWriter();
	} else {
	writer = new PpmWriter(useRawbits);
	}
	}

	// make copy of params; we'll clear keys as we consume them.
	if (params != null) {
	params = new HashMap<String,Object>(params);
	} else {
	params = new HashMap<String,Object>();
	}

	// clear format key.
	if (params.containsKey(PARAM_KEY_FORMAT)) {
	params.remove(PARAM_KEY_FORMAT);
	}

	if (params.size() > 0) {
	final Object firstKey = params.keySet().iterator().next();
	throw new ImageWriteException("Unknown parameter: " + firstKey);
	}

	writer.writeImage(src, os, params);
	}

	/**
	* Extracts embedded XML metadata as XML string.
	* <p>
	*
	* @param byteSource
	* File containing image data.
	* @param params
	* Map of optional parameters, defined in ImagingConstants.
	* @return Xmp Xml as String, if present. Otherwise, returns null.
	*/
	@Override
	public String getXmpXml(final ByteSource byteSource, final Map<String,Object> params)
	throws ImageReadException, IOException {
	return null;
	}
	}