in thumbnails4j-pdf/src/main/java/co/elastic/thumbnails4j/pdf/PDFThumbnailer.java [122:135]
private List<COSDictionary> collectImages(COSDictionary dictionary){
List<COSDictionary> values = new ArrayList<>();
for(Map.Entry<COSName, COSBase> entry : dictionary.entrySet()){
COSBase value = unwrapPDFObject(entry.getValue());
if (value instanceof COSDictionary) {
if (isImage((COSDictionary) value)){
values.add((COSDictionary) value);
} else {
values.addAll(collectImages((COSDictionary) value));
}
}
}
return values;
}