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0d4c3bcdcf
Adds a processing mode that removes the invisible (render mode 3) OCR text layer in place. Unlike `--ocr-engine none --force-ocr`, it does not rasterize the page, so images and visible content are preserved unchanged and the output is smaller rather than larger. Options that require rasterization or OCR (--deskew, --clean, --sidecar, etc.) are rejected. Only invisible text is removed; text drawn as visible glyphs under an opaque image (some OCR engines, and OCRmyPDF v2.2 and earlier) cannot be removed this way, as documented. Closes #1435.
72 lines
2.5 KiB
Python
72 lines
2.5 KiB
Python
# SPDX-FileCopyrightText: 2026 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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"""Tests for --mode strip (remove the OCR text layer in place)."""
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from __future__ import annotations
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import pikepdf
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import pytest
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from ocrmypdf.exceptions import BadArgsError
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from ocrmypdf.pdfinfo import PdfInfo
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from .conftest import check_ocrmypdf, run_ocrmypdf_api
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def _image_raw_bytes(pdf_path):
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"""Return raw (still-compressed) stream bytes of each image on page 1."""
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out = []
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with pikepdf.open(pdf_path) as pdf:
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resources = pdf.pages[0].get('/Resources', {})
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for _name, xobj in resources.get('/XObject', {}).items():
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if xobj.get('/Subtype') == pikepdf.Name.Image:
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out.append(bytes(xobj.read_raw_bytes()))
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return out
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def test_mode_strip_removes_ocr_layer(resources, outpdf):
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"""--mode strip removes the invisible OCR layer without rasterizing.
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The page image is preserved byte-for-byte and the output is no larger than
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the input.
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"""
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input_pdf = resources / 'graph_ocred.pdf'
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assert PdfInfo(input_pdf, detailed_analysis=True)[0].has_text
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out = check_ocrmypdf(
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input_pdf, outpdf, '--mode', 'strip', '--output-type', 'pdf', '--optimize', '0'
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)
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info = PdfInfo(out, detailed_analysis=True)
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assert len(info) == 1, "page count must be unchanged"
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assert not info[0].has_text, "OCR text layer should be removed"
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assert _image_raw_bytes(out) == _image_raw_bytes(input_pdf), (
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"page image must be preserved byte-for-byte (no rasterization)"
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)
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assert out.stat().st_size <= input_pdf.stat().st_size, (
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"removing the text layer must not grow the file"
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)
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def test_mode_strip_preserves_visible_text(resources, outpdf):
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"""--mode strip leaves visible/born-digital text untouched (render mode != 3).
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type3_font_nomapping.pdf is born-digital text with no images (the #1608
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case): its visible text must survive strip, which only removes invisible
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OCR text.
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"""
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input_pdf = resources / 'type3_font_nomapping.pdf'
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out = check_ocrmypdf(
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input_pdf, outpdf, '--mode', 'strip', '--output-type', 'pdf', '--optimize', '0'
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)
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assert PdfInfo(out, detailed_analysis=True)[0].has_text
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def test_mode_strip_rejects_image_processing_options(resources, no_outpdf):
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"""Options requiring rasterization/OCR are rejected in strip mode."""
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with pytest.raises(BadArgsError, match=r'--deskew'):
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run_ocrmypdf_api(
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resources / 'graph_ocred.pdf', no_outpdf, '--mode', 'strip', '--deskew'
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)
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