@Override
    protected List<PackagePart> getMainDocumentParts() {
        List<PackagePart> parts = new ArrayList<>();
        //TODO: consider: getPackage().getPartsByName(Pattern.compile("/ppt/embeddings/.*?
        //TODO: consider: getPackage().getPartsByName(Pattern.compile("/ppt/media/.*?
        PackageRelationshipCollection slidePRC = null;
        try {
            slidePRC = mainDocument.getRelationshipsByType(XSLFRelation.SLIDE.getRelation());
        } catch (InvalidFormatException e) {
            metadata.add(TikaCoreProperties.TIKA_META_EXCEPTION_WARNING,
                    ExceptionUtils.getStackTrace(e));

        }
        if (slidePRC != null) {
            for (int i = 0; i < slidePRC.size(); i++) {
                PackagePart slidePart = null;
                try {
                    slidePart = mainDocument.getRelatedPart(slidePRC.getRelationship(i));
                } catch (InvalidFormatException e) {
                    metadata.add(TikaCoreProperties.TIKA_META_EXCEPTION_WARNING,
                            ExceptionUtils.getStackTrace(e));
                }
                addSlideParts(slidePart, parts);
            }
        }

        parts.add(mainDocument);
        for (String rel : new String[]{XSLFRelation.SLIDE_MASTER.getRelation(), HANDOUT_MASTER}) {

            PackageRelationshipCollection prc = null;
            try {
                prc = mainDocument.getRelationshipsByType(rel);
            } catch (InvalidFormatException e) {
                metadata.add(TikaCoreProperties.TIKA_META_EXCEPTION_WARNING,
                        ExceptionUtils.getStackTrace(e));
            }
            if (prc != null) {
                for (int i = 0; i < prc.size(); i++) {
                    PackagePart pp = null;
                    try {
                        pp = mainDocument.getRelatedPart(prc.getRelationship(i));
                    } catch (InvalidFormatException e) {
                        metadata.add(TikaCoreProperties.TIKA_META_EXCEPTION_WARNING,
                                ExceptionUtils.getStackTrace(e));
                    }
                    if (pp != null) {
                        parts.add(pp);
                    }
                }
            }
        }

        return parts;
    }
In PowerPoint files, slides have things embedded in them,
and slide drawings which have the images
tika-parsers/tika-parsers-standard/tika-parsers-standard-modules/tika-parser-microsoft-module/src/main/java/org/apache/tika/parser/microsoft/ooxml/SXSLFPowerPointExtractorDecorator.java