Working with metadata in PNG images Leave feedback
The GroupDocs.Metadata API supports extracting format-specific information from PNG images.
The following are the steps to read the native PNG metadata.
- Load a PNG image
- Get the root metadata package
- Extract the native metadata package using PngRootPackage.getPngPackage
- Read the PNG metadata properties
advanced_usage.managing_metadata_for_specific_formats.
try (Metadata metadata = new Metadata(Constants.InputPng)) {
PngRootPackage root = metadata.getRootPackageGeneric();
for (PngTextChunk chunk : root.getPngPackage().getTextChunks()) {
System.out.println(chunk.getKeyword());
System.out.println(chunk.getText());
if (chunk instanceof PngCompressedTextChunk) {
PngCompressedTextChunk compressedChunk = (PngCompressedTextChunk) chunk;
System.out.println(compressedChunk.getCompressionMethod());
}
if (chunk instanceof PngInternationalTextChunk) {
PngInternationalTextChunk internationalChunk = (PngInternationalTextChunk) chunk;
System.out.println(internationalChunk.isCompressed());
System.out.println(internationalChunk.getLanguage());
System.out.println(internationalChunk.getTranslatedKeyword());
}
}
}
GroupDocs.Metadata for Java allows managing XMP metadata in PNG images. For more details please refer to the following guide: Working with XMP Metadata.
The code sample below shows how to update XMP properties in a PNG image. If the image has no XMP package or the required schemes yet, they are created first.
advanced_usage.managing_metadata_for_specific_formats.
try (Metadata metadata = new Metadata(Constants.PngWithXmp)) {
IXmp root = (IXmp) metadata.getRootPackage();
if (root.getXmpPackage() == null) {
root.setXmpPackage(new XmpPacketWrapper());
}
if (root.getXmpPackage().getSchemes().getDublinCore() == null) {
root.getXmpPackage().getSchemes().setDublinCore(new XmpDublinCorePackage());
}
root.getXmpPackage().getSchemes().getDublinCore().setFormat("image/png");
root.getXmpPackage().getSchemes().getDublinCore().setRights("Copyright (C) 2011-2026 GroupDocs. All Rights Reserved.");
root.getXmpPackage().getSchemes().getDublinCore().setSubject("test");
if (root.getXmpPackage().getSchemes().getXmpBasic() == null) {
root.getXmpPackage().getSchemes().setXmpBasic(new XmpBasicPackage());
}
root.getXmpPackage().getSchemes().getXmpBasic().setCreateDate(new Date());
root.getXmpPackage().getSchemes().getXmpBasic().setLabel("GroupDocs");
root.getXmpPackage().getSchemes().getXmpBasic().setRating(5);
root.getXmpPackage().getSchemes().getXmpBasic().setCreatorTool("GroupDocs.Metadata");
// ...
metadata.save(Constants.OutputPng);
}
The GroupDocs.Metadata API supports handling EXIF metadata in PNG images. Please find appropriate code samples in the Working with EXIF Metadata section.
You may easily run the code above and see the feature in action in our GitHub examples:
The PNG Metadata Editing app is available to view and edit metadata of PNG images, including text chunks, XMP, EXIF, and other properties.
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