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https://issues.apache.org/jira/browse/PDFBOX-6235?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=18104021#comment-18104021
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ASF subversion and git services commented on PDFBOX-6235:
---------------------------------------------------------
Commit 1937078 from Tilman Hausherr in branch 'pdfbox/branches/2.0'
[ https://svn.apache.org/r1937078 ]
PDFBOX-6235: optimize
> JPEGFactory.createFromImage() throws NullPointerException for 4-component
> (CMYK) BufferedImages
> -----------------------------------------------------------------------------------------------
>
> Key: PDFBOX-6235
> URL: https://issues.apache.org/jira/browse/PDFBOX-6235
> Project: PDFBox
> Issue Type: Bug
> Components: PDModel
> Affects Versions: 2.0.36, 3.0.1 PDFBox, 3.0.7 PDFBox
> Environment: PDFBox 3.0.1
> Java: Amazon Corretto 21.0.8+9-LTS (aarch64)
> OS: macOS (Apple Silicon)
> Reporter: Seungmin Lee
> Priority: Minor
> Labels: CMYK
> Fix For: 2.0.38, 3.0.9 PDFBox, 4.0.0
>
> Attachments: PDFBOX-6235-cmyk.jpg, PDFBOX-6235-cmyk.pdf,
> PDFBOX-6235-decode-comparison.png, PDFBOX-6235.patch
>
>
> JPEGFactory.createFromImage() fails with a NullPointerException for any
> BufferedImage backed by a 4-component CMYK color space -- for example the
> result of ImageIO.read() on a CMYK JPEG, which is common for print-ready
> assets.
> Reproduced on 2.0.36, 3.0.1 and 3.0.7 (same failure, only the line number
> differs: 396 / 372 / 376). The same unguarded dereference is still present on
> trunk.
> h3. Root cause
> encodeImageToJPEGStream() dereferences the app0JFIF metadata node without a
> null check:
> {code:java}
> Element tree = (Element) data.getAsTree("javax_imageio_jpeg_image_1.0");
> Element jfif = (Element) tree.getElementsByTagName("app0JFIF").item(0);
> String dpiString = Integer.toString(dpi);
> jfif.setAttribute("Xdensity", dpiString); // <-- NPE
> jfif.setAttribute("Ydensity", dpiString);
> jfif.setAttribute("resUnits", "1");
> {code}
> The JFIF APP0 segment is only defined for 1-component (grayscale) and
> 3-component (YCbCr) JPEGs. When the ImageIO JPEG writer encodes a 4-component
> image it emits an Adobe APP14 marker instead, so the default metadata tree
> contains no "app0JFIF" node and item(0) returns null.
> Note that the NPE comes from the metadata of the *re-encoded output*, not
> from the input file -- a CMYK input JPEG that does carry a JFIF APP0 marker
> fails just the same.
> This appears to be an oversight rather than intentionally unsupported input:
> getColorSpaceFromAWT() explicitly handles ColorSpace.TYPE_CMYK, so the
> factory otherwise looks intended to accept 4-component images.
> h3. Steps to reproduce
> 1. Create a 4-component CMYK JPEG (no attachment needed):
> {noformat}
> magick -size 200x200 gradient:red-blue -colorspace CMYK cmyk.jpg
> {noformat}
> Verify with {{file cmyk.jpg}} -> "JPEG image data, baseline, precision 8,
> 200x200, components 4"
> 2. Run:
> {code:java}
> BufferedImage src = ImageIO.read(new File("cmyk.jpg"));
> // src.getType() == TYPE_CUSTOM (0)
> // src.getColorModel().getNumComponents() == 4
> // src.getColorModel().getColorSpace().getType() == ColorSpace.TYPE_CMYK (9)
> try (PDDocument doc = new PDDocument()) {
> JPEGFactory.createFromImage(doc, src);
> }
> {code}
> h3. Actual result
> {noformat}
> java.lang.NullPointerException: Cannot invoke
> "org.w3c.dom.Element.setAttribute(String, String)" because "jfif" is null
> at
> org.apache.pdfbox.pdmodel.graphics.image.JPEGFactory.encodeImageToJPEGStream(JPEGFactory.java:376)
> at
> org.apache.pdfbox.pdmodel.graphics.image.JPEGFactory.createJPEG(JPEGFactory.java:312)
> at
> org.apache.pdfbox.pdmodel.graphics.image.JPEGFactory.createFromImage(JPEGFactory.java:278)
> at
> org.apache.pdfbox.pdmodel.graphics.image.JPEGFactory.createFromImage(JPEGFactory.java:255)
> at
> org.apache.pdfbox.pdmodel.graphics.image.JPEGFactory.createFromImage(JPEGFactory.java:233)
> {noformat}
> (stack trace from 3.0.7)
> h3. Expected result
> Either a PDImageXObject is created with a DeviceCMYK color space, or a
> descriptive exception is thrown stating that 4-component images are not
> supported.
> h3. Suggested fix
> Guard the dereference. The DPI metadata simply cannot be expressed in a
> non-JFIF stream, so skipping those three attributes when jfif is null seems
> sufficient:
> {code:java}
> Element jfif = (Element) tree.getElementsByTagName("app0JFIF").item(0);
> if (jfif != null)
> {
> String dpiString = Integer.toString(dpi);
> jfif.setAttribute("Xdensity", dpiString);
> jfif.setAttribute("Ydensity", dpiString);
> jfif.setAttribute("resUnits", "1"); // 1 = dots/inch
> }
> {code}
> h3. Workaround
> When the image does not need resampling, embedding the original bytes with
> JPEGFactory.createFromByteArray() avoids the re-encode entirely and also
> preserves the DeviceCMYK color space. This is not an option when the image
> must be resized.
> Possibly related (all older, different symptoms): PDFBOX-2057, PDFBOX-2128,
> PDFBOX-3823.
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