fix(document_loaders): handle 1-bit images in PyPDFParser.extract_images_from_page#542
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Sonic-79 wants to merge 1 commit intolangchain-ai:mainfrom
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fix(document_loaders): handle 1-bit images in PyPDFParser.extract_images_from_page#542Sonic-79 wants to merge 1 commit intolangchain-ai:mainfrom
Sonic-79 wants to merge 1 commit intolangchain-ai:mainfrom
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…ges_from_page Read /BitsPerComponent from PDF image XObject and unpack 1-bit monochrome images correctly using np.unpackbits(), accounting for row-level byte-boundary padding. Adds a ValueError catch as safety net for unexpected data shapes. Closes langchain-ai#307 Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
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Summary
ValueError: cannot reshape array of size N into shape (H,W,newaxis)whenextract_images_from_page()encounters 1-bit monochrome images in PDFs (common in scanned documents using CCITT Fax, JBIG2, or FlateDecode compression)/BitsPerComponentfrom PDF image XObject and unpack 1-bit images correctly usingnp.unpackbits(), accounting for row-level byte-boundary paddingValueErrorcatch as safety net for other unexpected data shapesRoot cause: The code assumes every pixel occupies one byte (
dtype=np.uint8), but 1-bit images pack 8 pixels per byte. For example, a 430×645 image expects 277,350 bytes but only has 34,830 — exactly 1/8th, because each bit represents one pixel.Closes #307
Related: langchain-ai/langchain#31724
Test plan
test_1bit_image_does_not_raise— regression test with real-world dimensions (430×645, CCITT)test_1bit_pixel_values— verifies correct bit unpacking and 0/255 scalingtest_1bit_row_padding— verifies correct handling of non-byte-aligned row widthstest_8bit_image_unaffected— confirms no regression for standard 8-bit imagesAI Disclosure
This fix was developed with assistance from Claude (Anthropic). The root cause analysis, fix design, and testing were performed collaboratively between a human developer and AI.
🤖 Generated with Claude Code