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  1. PO
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    <p>I had to do the the same thing some days ago.. I have not found the exact solution on the internet either but looking at the <code>com.sun.imageio.plugins.png.PNGMetadata</code> class I could achieve some results.. </p> <p>To write a custom metadata to a PNG file:</p> <pre><code>public byte[] writeCustomData(BufferedImage buffImg, String key, String value) throws Exception { ImageWriter writer = ImageIO.getImageWritersByFormatName("png").next(); ImageWriteParam writeParam = writer.getDefaultWriteParam(); ImageTypeSpecifier typeSpecifier = ImageTypeSpecifier.createFromBufferedImageType(BufferedImage.TYPE_INT_RGB); //adding metadata IIOMetadata metadata = writer.getDefaultImageMetadata(typeSpecifier, writeParam); IIOMetadataNode textEntry = new IIOMetadataNode("tEXtEntry"); textEntry.setAttribute("keyword", key); textEntry.setAttribute("value", value); IIOMetadataNode text = new IIOMetadataNode("tEXt"); text.appendChild(textEntry); IIOMetadataNode root = new IIOMetadataNode("javax_imageio_png_1.0"); root.appendChild(text); metadata.mergeTree("javax_imageio_png_1.0", root); //writing the data ByteArrayOutputStream baos = new ByteArrayOutputStream(); ImageOutputStream stream = ImageIO.createImageOutputStream(baos); writer.setOutput(stream); writer.write(metadata, new IIOImage(buffImg, null, metadata), writeParam); stream.close(); return baos.toByteArray(); } </code></pre> <p>Then, to read the data:</p> <pre><code>public String readCustomData(byte[] imageData, String key) throws IOException{ ImageReader imageReader = ImageIO.getImageReadersByFormatName("png").next(); imageReader.setInput(ImageIO.createImageInputStream(new ByteArrayInputStream(imageData)), true); // read metadata of first image IIOMetadata metadata = imageReader.getImageMetadata(0); //this cast helps getting the contents PNGMetadata pngmeta = (PNGMetadata) metadata; NodeList childNodes = pngmeta.getStandardTextNode().getChildNodes(); for (int i = 0; i &lt; childNodes.getLength(); i++) { Node node = childNodes.item(i); String keyword = node.getAttributes().getNamedItem("keyword").getNodeValue(); String value = node.getAttributes().getNamedItem("value").getNodeValue(); if(key.equals(keyword)){ return value; } } return null; } </code></pre>
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    1. POWriting image metadata in Java, preferably PNG
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    1. USRogel Garcia
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      1. VTUpMod
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    1. COthanks this really helped me out
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      1. USAlexis Laporte
 

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