I have an application that I want to export high-resolution (or rather, high pixel density?) images for printing - for example, I want images that print at 250 dots per inch (DPI), instead of the default, which I understand to be 72 DPI.
I'm using a BufferedImage with a Graphics2D object to draw the image, then ImageIO.write() to save the image.
Any idea how I can set the DPI?
Kurt's answer showed the way, still it took me quite some time to get it run, so here is the code that sets DPI when saving a PNG. There is a lot to do to get the proper writers and such...
private BufferedImage gridImage;
...
private void saveGridImage(File output) throws IOException {
output.delete();
final String formatName = "png";
for (Iterator<ImageWriter> iw = ImageIO.getImageWritersByFormatName(formatName); iw.hasNext();) {
ImageWriter writer = iw.next();
ImageWriteParam writeParam = writer.getDefaultWriteParam();
ImageTypeSpecifier typeSpecifier = ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB);
IIOMetadata metadata = writer.getDefaultImageMetadata(typeSpecifier, writeParam);
if (metadata.isReadOnly() || !metadata.isStandardMetadataFormatSupported()) {
continue;
}
setDPI(metadata);
final ImageOutputStream stream = ImageIO.createImageOutputStream(output);
try {
writer.setOutput(stream);
writer.write(metadata, new IIOImage(gridImage, null, metadata), writeParam);
} finally {
stream.close();
}
break;
}
}
private void setDPI(IIOMetadata metadata) throws IIOInvalidTreeException {
// for PMG, it's dots per millimeter
double dotsPerMilli = 1.0 * DPI / 10 / INCH_2_CM;
IIOMetadataNode horiz = new IIOMetadataNode("HorizontalPixelSize");
horiz.setAttribute("value", Double.toString(dotsPerMilli));
IIOMetadataNode vert = new IIOMetadataNode("VerticalPixelSize");
vert.setAttribute("value", Double.toString(dotsPerMilli));
IIOMetadataNode dim = new IIOMetadataNode("Dimension");
dim.appendChild(horiz);
dim.appendChild(vert);
IIOMetadataNode root = new IIOMetadataNode("javax_imageio_1.0");
root.appendChild(dim);
metadata.mergeTree("javax_imageio_1.0", root);
}
If you want to set dpi for TIFF, try to do that by next steps:
private static IIOMetadata createMetadata(ImageWriter writer, ImageWriteParam writerParams, int resolution) throws
IIOInvalidTreeException
{
// Get default metadata from writer
ImageTypeSpecifier type = ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_BYTE_GRAY);
IIOMetadata meta = writer.getDefaultImageMetadata(type, writerParams);
// Convert default metadata to TIFF metadata
TIFFDirectory dir = TIFFDirectory.createFromMetadata(meta);
// Get {X,Y} resolution tags
BaselineTIFFTagSet base = BaselineTIFFTagSet.getInstance();
TIFFTag tagXRes = base.getTag(BaselineTIFFTagSet.TAG_X_RESOLUTION);
TIFFTag tagYRes = base.getTag(BaselineTIFFTagSet.TAG_Y_RESOLUTION);
// Create {X,Y} resolution fields
TIFFField fieldXRes = new TIFFField(tagXRes, TIFFTag.TIFF_RATIONAL, 1, new long[][] { { resolution, 1 } });
TIFFField fieldYRes = new TIFFField(tagYRes, TIFFTag.TIFF_RATIONAL, 1, new long[][] { { resolution, 1 } });
// Add {X,Y} resolution fields to TIFFDirectory
dir.addTIFFField(fieldXRes);
dir.addTIFFField(fieldYRes);
// Add unit field to TIFFDirectory (change to RESOLUTION_UNIT_CENTIMETER if necessary)
dir.addTIFFField(new TIFFField(base.getTag(BaselineTIFFTagSet.TAG_RESOLUTION_UNIT), BaselineTIFFTagSet.RESOLUTION_UNIT_INCH));
// Return TIFF metadata so it can be picked up by the IIOImage
return dir.getAsMetadata();
}
Also, similar way you can setting up any TIFF tag.
Read more at the source
i am using this code for tiff file in my project and it works well..
import java.awt.image.BufferedImage;
import java.awt.image.RenderedImage;
import java.io.File;
import java.io.FileOutputStream;
import java.io.IOException;
import java.io.OutputStream;
import java.util.ArrayList;
import java.util.List;
import javax.imageio.ImageIO;
import javax.media.jai.NullOpImage;
import javax.media.jai.OpImage;
import javax.media.jai.PlanarImage;
import com.sun.media.jai.codec.FileSeekableStream;
import com.sun.media.jai.codec.ImageCodec;
import com.sun.media.jai.codec.ImageDecoder;
import com.sun.media.jai.codec.ImageEncoder;
import com.sun.media.jai.codec.SeekableStream;
import com.sun.media.jai.codec.TIFFEncodeParam;
import com.sun.media.jai.codec.TIFFField;
class SetDDPI
{
static void tiff_Maker(List<BufferedImage> output, String result) throws IOException
{
TIFFEncodeParam params = new TIFFEncodeParam();
OutputStream out = new FileOutputStream(result);
List<BufferedImage> imageList = new ArrayList<BufferedImage>();
for (int i = 1; i < output.size(); i++)
{
imageList.add(output.get(i));
}
params.setWriteTiled(true);
params.setCompression(TIFFEncodeParam.COMPRESSION_GROUP4);
params.setExtraImages(imageList.iterator());
TIFFField[] extras = new TIFFField[2];
extras[0] = new TIFFField(282, TIFFField.TIFF_RATIONAL, 1, (Object) new long[][] { { (long) 300, (long) 1 },
{ (long) 0, (long) 0 } });
extras[1] = new TIFFField(283, TIFFField.TIFF_RATIONAL, 1, (Object) new long[][] { { (long) 300, (long) 1 },
{ (long) 0, (long) 0 } });
params.setExtraFields(extras);
ImageEncoder encoder = ImageCodec.createImageEncoder("tiff", out, params);
encoder.encode(output.get(0));
out.close();
}
static List<BufferedImage> tiff_Extractor(File tiff) throws IOException
{
List<BufferedImage> images = new ArrayList<BufferedImage>();
SeekableStream ss = new FileSeekableStream(tiff);
ImageDecoder decoder = ImageCodec.createImageDecoder("tiff", ss, null);
int numPages = decoder.getNumPages();
for (int j = 0; j < numPages; j++)
{
PlanarImage op = new NullOpImage(decoder.decodeAsRenderedImage(j), null, null, OpImage.OP_IO_BOUND);
images.add(op.getAsBufferedImage());
}
return images;
}
}
this is to set 300 DPI of Tiff image. you can change it according to your need.
extras[0] = new TIFFField(282, TIFFField.TIFF_RATIONAL, 1, (Object) new
long[][] { { (long) 300, (long) 1 },{ (long) 0, (long) 0 } });
extras[1] = new TIFFField(283, TIFFField.TIFF_RATIONAL, 1, (Object) new
long[][] { { (long) 300, (long) 1 },{ (long) 0, (long) 0 } });
