如何使用 java 获取图像的高度和宽度？

Question

Is there any other way besides using ImageIO.read to get image height and width?

Because I encounter an issue that locks up the thread.

at com.sun.medialib.codec.jpeg.Decoder.njpeg_decode(Native Method)      
at com.sun.medialib.codec.jpeg.Decoder.decode(Decoder.java:87)      
at com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader.decode(CLibJPEGImageReader.java:73)     
 - locked <0xd96fb668> (a com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader)      
at com.sun.media.imageioimpl.plugins.clib.CLibImageReader.getImage(CLibImageReader.java:320)    
 - locked <0xd96fb668> (a com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader)     
 at com.sun.media.imageioimpl.plugins.clib.CLibImageReader.read(CLibImageReader.java:384)   
 - locked <0xd96fb668> (a com.sun.media.imageioimpl.plugins.jpeg.CLibJPEGImageReader)      
at javax.imageio.ImageIO.read(ImageIO.java:1400)      
at javax.imageio.ImageIO.read(ImageIO.java:1322)

This error only occurs on a Sun app server and therefore I suspect that it is a Sun bug.

Answer 1

Here is something very simple and handy.

BufferedImage bimg = ImageIO.read(new File(filename));
int width          = bimg.getWidth();
int height         = bimg.getHeight();

Answer 2

This is a rewrite of the great post by @Kay, which throws IOException and provides an early exit:

/**
 * Gets image dimensions for given file 
 * @param imgFile image file
 * @return dimensions of image
 * @throws IOException if the file is not a known image
 */
public static Dimension getImageDimension(File imgFile) throws IOException {
  int pos = imgFile.getName().lastIndexOf(".");
  if (pos == -1)
    throw new IOException("No extension for file: " + imgFile.getAbsolutePath());
  String suffix = imgFile.getName().substring(pos + 1);
  Iterator<ImageReader> iter = ImageIO.getImageReadersBySuffix(suffix);
  while(iter.hasNext()) {
    ImageReader reader = iter.next();
    try {
      ImageInputStream stream = new FileImageInputStream(imgFile);
      reader.setInput(stream);
      int width = reader.getWidth(reader.getMinIndex());
      int height = reader.getHeight(reader.getMinIndex());
      return new Dimension(width, height);
    } catch (IOException e) {
      log.warn("Error reading: " + imgFile.getAbsolutePath(), e);
    } finally {
      reader.dispose();
    }
  }

  throw new IOException("Not a known image file: " + imgFile.getAbsolutePath());
}

I guess my rep is not high enough for my input to be considered worthy as a reply.

Answer 3

I have found another way to read an image size (more generic). You can use ImageIO class in cooperation with ImageReaders. Here is the sample code:

private Dimension getImageDim(final String path) {
    Dimension result = null;
    String suffix = this.getFileSuffix(path);
    Iterator<ImageReader> iter = ImageIO.getImageReadersBySuffix(suffix);
    if (iter.hasNext()) {
        ImageReader reader = iter.next();
        try {
            ImageInputStream stream = new FileImageInputStream(new File(path));
            reader.setInput(stream);
            int width = reader.getWidth(reader.getMinIndex());
            int height = reader.getHeight(reader.getMinIndex());
            result = new Dimension(width, height);
        } catch (IOException e) {
            log(e.getMessage());
        } finally {
            reader.dispose();
        }
    } else {
        log("No reader found for given format: " + suffix));
    }
    return result;
}

Note that getFileSuffix is method that returns extension of path without "." so eg: png, jpg etc. Example implementation is:

private String getFileSuffix(final String path) {
    String result = null;
    if (path != null) {
        result = "";
        if (path.lastIndexOf('.') != -1) {
            result = path.substring(path.lastIndexOf('.'));
            if (result.startsWith(".")) {
                result = result.substring(1);
            }
        }
    }
    return result;
}

This solution is very quick as only image size is read from the file and not the whole image. I tested it and there is no comparison to ImageIO.read performance. I hope someone will find this useful.

Answer 4

I tried to test performance using some of the various approaches listed. It's hard to make a rigorous test as many factors affect the result. I prepared two folders, one with 330 jpg files and another one with 330 png files. The average file size was 4Mb in both cases. Then I called getDimension for each file. Each implementation of getDimension method and each image type was tested separately (separate run). Here is the execution times that I got (first number for jpg, second number for png):

1(Apurv) - 101454ms, 84611ms
2(joinJpegs) - 471ms, N/A
3(Andrew Taylor) - 707ms, 68ms
4(Karussell, ImageIcon) - 106655ms, 100898ms
5(user350756) - 2649ms, 68ms

It's obvious that some methods load the whole file in order to get dimensions while others get by just reading some header information from the image. I think these numbers may be useful when application performance is critical.

Thank you everyone for the contribution to this thread - very helpful.

Answer 5

You can load jpeg binary data as a file and parse the jpeg headers yourself. The one you are looking for is the 0xFFC0 or Start of Frame header:

Start of frame marker (FFC0)

* the first two bytes, the length, after the marker indicate the number of bytes, including the two length bytes, that this header contains
* P -- one byte: sample precision in bits (usually 8, for baseline JPEG)
* Y -- two bytes
* X -- two bytes
* Nf -- one byte: the number of components in the image
      o 3 for color baseline JPEG images
      o 1 for grayscale baseline JPEG images

* Nf times:
      o Component ID -- one byte
      o H and V sampling factors -- one byte: H is first four bits and V is second four bits
      o Quantization table number-- one byte

The H and V sampling factors dictate the final size of the component they are associated with. For instance, the color space defaults to YCbCr and the H and V sampling factors for each component, Y, Cb, and Cr, default to 2, 1, and 1, respectively (2 for both H and V of the Y component, etc.) in the Jpeg-6a library by the Independent Jpeg Group. While this does mean that the Y component will be twice the size of the other two components--giving it a higher resolution, the lower resolution components are quartered in size during compression in order to achieve this difference. Thus, the Cb and Cr components must be quadrupled in size during decompression.

For more info about the headers check out wikipedia's jpeg entry or I got the above info here .

I used a method similar to the code below which I got from this post at the sun forums:

import java.awt.Dimension;
import java.io.*;

public class JPEGDim {

public static Dimension getJPEGDimension(File f) throws IOException {
    FileInputStream fis = new FileInputStream(f);

    // check for SOI marker
    if (fis.read() != 255 || fis.read() != 216)
        throw new RuntimeException("SOI (Start Of Image) marker 0xff 0xd8 missing");

    Dimension d = null;

    while (fis.read() == 255) {
        int marker = fis.read();
        int len = fis.read() << 8 | fis.read();

        if (marker == 192) {
            fis.skip(1);

            int height = fis.read() << 8 | fis.read();
            int width = fis.read() << 8 | fis.read();

            d = new Dimension(width, height);
            break;
        }

        fis.skip(len - 2);
    }

    fis.close();

    return d;
}

public static void main(String[] args) throws IOException {
    System.out.println(getJPEGDimension(new File(args[0])));
}

}

Answer 6

Simple way:

BufferedImage readImage = null;

try {
    readImage = ImageIO.read(new File(your path);
    int h = readImage.getHeight();
    int w = readImage.getWidth();
} catch (Exception e) {
    readImage = null;
}

Answer 7

You could use the Toolkit, no need for ImageIO

Image image = Toolkit.getDefaultToolkit().getImage(file.getAbsolutePath());
int width = image.getWidth(null);
int height = image.getHeight(null);

If you don't want to handle the loading of the image do

ImageIcon imageIcon = new ImageIcon(file.getAbsolutePath());
int height = imageIcon.getIconHeight();
int width = imageIcon.getIconWidth();

Answer 8

Problem with ImageIO.read is that it is really slow. All you need to do is to read image header to get the size. ImageIO.getImageReader is perfect candidate.

Here is the Groovy example, but the same thing applies to Java

def stream = ImageIO.createImageInputStream(newByteArrayInputStream(inputStream))
def formatReader = ImageIO.getImageWritersByFormatName(format).next() 
def reader = ImageIO.getImageReader(formatReader)
reader.setInput(stream, true)

println "width:reader.getWidth(0) -> height: reader.getHeight(0)"

The performance was the same as using SimpleImageInfo java library.

https://github.com/cbeust/personal/blob/master/src/main/java/com/beust/SimpleImageInfo.java

Answer 9

You can get width and height of image with BufferedImage object using java.

public void setWidthAndHeightImage(FileUploadEvent event){
    byte[] imageTest = event.getFile().getContents();
                baiStream = new ByteArrayInputStream(imageTest );
                BufferedImage bi = ImageIO.read(baiStream);
                //get width and height of image
                int imageWidth = bi.getWidth();
                int imageHeight = bi.getHeight();
    }

Answer 10

To get a Buffered Image with ImageIO.read is a very heavy method, as it's creating a complete uncompressed copy of the image in memory. For png's you may also use pngj and the code:

if (png)
    PngReader pngr = new PngReader(file);
    width = pngr.imgInfo.cols;
    height = pngr.imgInfo.rows;
    pngr.close();
}

Answer 11

Having struggled with ImageIO a lot in the past years, I think Andrew Taylor 's solution is by far the best compromise (fast: not using ImageIO#read , and versatile). Thanks man!!

But I was a little frustrated to be compelled to use a local file (File/String), especially in cases where you want to check image sizes coming from, say, a multipart/form-data request where you usually retrieve InputPart / InputStream 's. So I quickly made a variant that accepts File , InputStream and RandomAccessFile , based on the ability of ImageIO#createImageInputStream to do so.

Of course, such a method with Object input , may only remain private and you shall create as many polymorphic methods as needed, calling this one. You can also accept Path with Path#toFile() and URL with URL#openStream() prior to passing to this method:

  private static Dimension getImageDimensions(Object input) throws IOException {

    try (ImageInputStream stream = ImageIO.createImageInputStream(input)) { // accepts File, InputStream, RandomAccessFile
      if(stream != null) {
        IIORegistry iioRegistry = IIORegistry.getDefaultInstance();
        Iterator<ImageReaderSpi> iter = iioRegistry.getServiceProviders(ImageReaderSpi.class, true);
        while (iter.hasNext()) {
          ImageReaderSpi readerSpi = iter.next();
          if (readerSpi.canDecodeInput(stream)) {
            ImageReader reader = readerSpi.createReaderInstance();
            try {
              reader.setInput(stream);
              int width = reader.getWidth(reader.getMinIndex());
              int height = reader.getHeight(reader.getMinIndex());
              return new Dimension(width, height);
            } finally {
              reader.dispose();
            }
          }
        }
        throw new IllegalArgumentException("Can't find decoder for this image");
      } else {
        throw new IllegalArgumentException("Can't open stream for this image");
      }
    }
  }

Answer 12

So unfortunately, after trying all the answers from above, I did not get them to work after tireless times of trying. So I decided to do the real hack myself and I go this to work for me. I trust it would work perfectly for you too.

I am using this simple method to get the width of an image generated by the app and yet to be upload later for verification:

Pls. take note: you would have to enable permissions in manifest for access storage.

/ I made it static and put in my Global class so I can reference or access it from just one source and if there is any modification, it would all have to be done at just one place. Just maintaining a DRY concept in java. (anyway):) /

public static int getImageWidthOrHeight(String imgFilePath) {

            Log.d("img path : "+imgFilePath);

            // Decode image size
            BitmapFactory.Options o = new BitmapFactory.Options();
            o.inJustDecodeBounds = true;
            BitmapFactory.decodeFile(imgFilePath, o);

            int width_tmp = o.outWidth, height_tmp = o.outHeight;

            Log.d("Image width : ", Integer.toString(width_tmp) );

            //you can decide to rather return height_tmp to get the height.

            return width_tmp;

}

Answer 13

byte[] bytes = file.getBytes();
InputStream inputStream = new ByteArrayInputStream(bytes);
BufferedImage image = ImageIO.read(inputStream);
imageWidth = image.getWidth();
imageHeight = image.getHeight();

Answer 14

public static Optional<Dimension> getImageDimensions(Path imageFile) {

    Optional<String> suffixOpt = getExtension(imageFile);
    Iterator<ImageReader> iter = ImageIO.getImageReadersBySuffix(suffixOpt.orElse(""));
    while (iter.hasNext()) {
        ImageReader reader = iter.next();
        try (ImageInputStream stream = new FileImageInputStream(imageFile.toFile())) {
            reader.setInput(stream);
            return Optional.of(new Dimension(reader.getWidth(reader.getMinIndex()),
                    reader.getHeight(reader.getMinIndex())));
        } catch (IOException e) {
            log.warn("Error reading: " + imageFile, e); //or however you want to handle the exception
        } finally {
            reader.dispose();
        }
    }
    return Optional.empty();
}

public static Optional<String> getExtension(Path file) {
    int pos = file.getFileName().toString().lastIndexOf(".");
    if (pos == -1) {
        return Optional.empty();
    }
    return Optional.of(file.getFileName().toString().substring(pos + 1));
}

Revised the method by @Andrew Taylor to use Optionals.

Also uses the Java's NIO Path to make the transition to Path.getExt easier in Java 21 (the second method can be removed and getExtension(imageFile) can be replaced with imageFile.getExtension() ).

Also uses the try-with-resources design from Java.

One could instead use an external library in place of the second method if that's preferable.

Using a Spliterator could be another way, though in the end the code became more verbose as little is gained by converting from an Iterator.

Answer 15

To get size of emf file without EMF Image Reader you can use code:

Dimension getImageDimForEmf(final String path) throws IOException {

    ImageInputStream inputStream = new FileImageInputStream(new File(path));

    inputStream.setByteOrder(ByteOrder.LITTLE_ENDIAN);

    // Skip magic number and file size
    inputStream.skipBytes(6*4);

    int left   = inputStream.readInt();
    int top    = inputStream.readInt();
    int right  = inputStream.readInt();
    int bottom = inputStream.readInt();

    // Skip other headers
    inputStream.skipBytes(30);

    int deviceSizeInPixelX = inputStream.readInt();
    int deviceSizeInPixelY = inputStream.readInt();

    int deviceSizeInMlmX = inputStream.readInt();
    int deviceSizeInMlmY = inputStream.readInt();

    int widthInPixel = (int) Math.round(0.5 + ((right - left + 1.0) * deviceSizeInPixelX / deviceSizeInMlmX) / 100.0);
    int heightInPixel = (int) Math.round(0.5 + ((bottom-top + 1.0) * deviceSizeInPixelY / deviceSizeInMlmY) / 100.0);

    inputStream.close();

    return new Dimension(widthInPixel, heightInPixel);
}