feat: add --mode strip to remove the OCR text layer without rasterizing

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.

docs/cookbook.md

@@ -249,19 +249,34 @@ case. Use `--tesseract-non-ocr-timeout` to control the timeout for
 non-OCR operations, if needed.
 :::
 
-### Remove all text or OCR from my PDF
+### Remove the OCR text layer from my PDF
 
-This is getting ridiculous, but OCRmyPDF can complete strip all textual
-information from a PDF and reconstruct it as a \"bag of images\" PDF.
+To remove the invisible OCR text layer while keeping the original pages
+exactly as they are -- no rasterizing, no change to images or visible
+content, and a smaller output file -- use `--mode strip`:
+
+```bash
+ocrmypdf --mode strip input.pdf output.pdf
+```
+
+Why would you want to do this? Perhaps you have a PDF where OCR failed to
+produce useful results and you simply want to get rid of it.
+
+`--mode strip` removes only text drawn as *invisible* (PDF text render
+mode 3), which is how OCRmyPDF and most OCR tools add a searchable layer
+over a scanned page. Some OCR products -- and OCRmyPDF v2.2 and earlier --
+instead draw *visible* text and paint an opaque image on top of it. That
+text is part of the visible page, so `--mode strip` cannot remove it
+without altering the page's appearance.
+
+To strip *all* text, including such visible text, rasterize the whole page
+into a \"bag of images\" PDF instead (this rebuilds every page as an image,
+so the file usually grows and vector content is lost):
 
 ```bash
 ocrmypdf --ocr-engine none --force-ocr input.pdf output.pdf
 ```
 
-Why would you want to do this? Perhaps you have a PDF where OCR fails to
-produce useful results, and just want to get rid of all OCR information.
-This command also removes OCR generated by third party tools.
-
 ### Optimize images without performing OCR
 
 You can also optimize all images without performing any OCR:

docs/releasenotes/version17.md

@@ -80,6 +80,13 @@
   interpreted "lots of diacritics - possibly poor OCR" hint, but now also emits
   Tesseract's raw message at debug verbosity (``-v 1``) so the original wording
   is available for diagnosis. {issue}`1566`
+- Added ``--mode strip``, which removes the invisible OCR text layer from a PDF
+  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. Only text drawn as invisible (PDF text render mode
+  3) is removed; some OCR engines -- and OCRmyPDF v2.2 and earlier -- express
+  text as visible glyphs covered by an opaque image, and that text cannot be
+  removed this way. {issue}`1435`
 
 ## v17.5.0
 

src/ocrmypdf/_graft.py

@@ -342,6 +342,14 @@ class OcrGrafter:
             ocr_tree: OCR tree for fpdf2 renderer.
             autorotate_correction: Orientation correction in degrees (0, 90, 180, 270).
         """
+        if self.context.options.mode == ProcessingMode.strip_text:
+            # Strip mode: remove the invisible OCR text layer in place without
+            # rasterizing or grafting anything. Honor --pages if specified.
+            options = self.context.options
+            if not options.pages or pageno in options.pages:
+                strip_invisible_text(self.pdf_base, self.pdf_base.pages[pageno])
+            return
+
         if ocr_output and ocr_tree:
             raise ValueError(
                 'Cannot specify both ocr_output and ocr_tree for fpdf2 renderer'

src/ocrmypdf/_options.py

@@ -43,12 +43,16 @@ class ProcessingMode(StrEnum):
     - ``force``: Rasterize all content and run OCR regardless of existing text
     - ``skip``: Skip OCR on pages that already have text
     - ``redo``: Re-OCR pages, stripping old invisible text layer
+    - ``strip``: Remove the invisible OCR text layer in place; do not OCR
     """
 
     default = 'default'
     force = 'force'
     skip = 'skip'
     redo = 'redo'
+    # User-facing value is '--mode strip'; the member is named strip_text to
+    # avoid shadowing str.strip on this str-based enum.
+    strip_text = 'strip'
 
 
 class TaggedPdfMode(StrEnum):
@@ -79,8 +83,7 @@ def _resolve_page_token(token: str, total_pages: int | None) -> int:
     if token.lower() == 'end':
         if total_pages is None:
             raise BadArgsError(
-                "'end' was used in --pages but the total page count is not yet "
-                "known"
+                "'end' was used in --pages but the total page count is not yet known"
             )
         return total_pages
     return int(token)

src/ocrmypdf/_pipeline.py

@@ -334,6 +334,11 @@ def is_ocr_required(page_context: PageContext) -> bool:
     pageinfo = page_context.pageinfo
     options = page_context.options
 
+    if options.mode == ProcessingMode.strip_text:
+        # Strip mode removes the OCR text layer in place; it never rasterizes
+        # or runs OCR. The stripping happens in OcrGrafter.graft_page.
+        return False
+
     ocr_required = True
 
     if options.pages and pageinfo.pageno not in options.pages:

src/ocrmypdf/_validation.py

@@ -17,7 +17,7 @@ import pikepdf
 
 from ocrmypdf._defaults import DEFAULT_ROTATE_PAGES_THRESHOLD
 from ocrmypdf._exec import unpaper
-from ocrmypdf._options import OcrOptions
+from ocrmypdf._options import OcrOptions, ProcessingMode
 from ocrmypdf._plugin_manager import OcrmypdfPluginManager
 from ocrmypdf.exceptions import (
     BadArgsError,
@@ -118,8 +118,36 @@ def check_options_preprocessing(options: OcrOptions) -> None:
         )
 
 
+def check_options_strip(options: OcrOptions) -> None:
+    """Reject options that cannot apply in strip mode.
+
+    ``--mode strip`` removes the OCR text layer in place without rasterizing or
+    running OCR, so image-processing and OCR-output options have no effect.
+    """
+    if options.mode != ProcessingMode.strip_text:
+        return
+    incompatible = {
+        '--deskew': options.deskew,
+        '--clean': options.clean,
+        '--clean-final': options.clean_final,
+        '--remove-background': options.remove_background,
+        '--rotate-pages': options.rotate_pages,
+        '--oversample': options.oversample,
+        '--remove-vectors': options.remove_vectors,
+        '--sidecar': options.sidecar,
+    }
+    used = sorted(name for name, value in incompatible.items() if value)
+    if used:
+        raise BadArgsError(
+            "--mode strip removes the OCR text layer without rasterizing or "
+            "running OCR, so these options have no effect and are not allowed: "
+            f"{', '.join(used)}"
+        )
+
+
 def _check_plugin_invariant_options(options: OcrOptions) -> None:
     check_platform()
+    check_options_strip(options)
     check_options_sidecar(options)
     check_options_preprocessing(options)
 

src/ocrmypdf/cli.py

@@ -327,7 +327,11 @@ Online documentation is located at:
         "'default' errors if text is found. "
         "'force' rasterizes all content and runs OCR (same as --force-ocr). "
         "'skip' skips pages with existing text (same as --skip-text). "
-        "'redo' re-OCRs pages, replacing old invisible text (same as --redo-ocr).",
+        "'redo' re-OCRs pages, replacing old invisible text (same as --redo-ocr). "
+        "'strip' removes the invisible OCR text layer without rasterizing or "
+        "running OCR, producing a smaller file; only text drawn as invisible "
+        "(render mode 3) is removed, so text from some OCR engines cannot be "
+        "removed this way.",
     )
     # Legacy flags for backward compatibility - these set the mode internally
     ocrsettings.add_argument(

tests/test_strip.py

@@ -0,0 +1,71 @@
+# SPDX-FileCopyrightText: 2026 James R. Barlow
+# SPDX-License-Identifier: MPL-2.0
+
+"""Tests for --mode strip (remove the OCR text layer in place)."""
+
+from __future__ import annotations
+
+import pikepdf
+import pytest
+
+from ocrmypdf.exceptions import BadArgsError
+from ocrmypdf.pdfinfo import PdfInfo
+
+from .conftest import check_ocrmypdf, run_ocrmypdf_api
+
+
+def _image_raw_bytes(pdf_path):
+    """Return raw (still-compressed) stream bytes of each image on page 1."""
+    out = []
+    with pikepdf.open(pdf_path) as pdf:
+        resources = pdf.pages[0].get('/Resources', {})
+        for _name, xobj in resources.get('/XObject', {}).items():
+            if xobj.get('/Subtype') == pikepdf.Name.Image:
+                out.append(bytes(xobj.read_raw_bytes()))
+    return out
+
+
+def test_mode_strip_removes_ocr_layer(resources, outpdf):
+    """--mode strip removes the invisible OCR layer without rasterizing.
+
+    The page image is preserved byte-for-byte and the output is no larger than
+    the input.
+    """
+    input_pdf = resources / 'graph_ocred.pdf'
+    assert PdfInfo(input_pdf, detailed_analysis=True)[0].has_text
+
+    out = check_ocrmypdf(
+        input_pdf, outpdf, '--mode', 'strip', '--output-type', 'pdf', '--optimize', '0'
+    )
+
+    info = PdfInfo(out, detailed_analysis=True)
+    assert len(info) == 1, "page count must be unchanged"
+    assert not info[0].has_text, "OCR text layer should be removed"
+    assert _image_raw_bytes(out) == _image_raw_bytes(input_pdf), (
+        "page image must be preserved byte-for-byte (no rasterization)"
+    )
+    assert out.stat().st_size <= input_pdf.stat().st_size, (
+        "removing the text layer must not grow the file"
+    )
+
+
+def test_mode_strip_preserves_visible_text(resources, outpdf):
+    """--mode strip leaves visible/born-digital text untouched (render mode != 3).
+
+    type3_font_nomapping.pdf is born-digital text with no images (the #1608
+    case): its visible text must survive strip, which only removes invisible
+    OCR text.
+    """
+    input_pdf = resources / 'type3_font_nomapping.pdf'
+    out = check_ocrmypdf(
+        input_pdf, outpdf, '--mode', 'strip', '--output-type', 'pdf', '--optimize', '0'
+    )
+    assert PdfInfo(out, detailed_analysis=True)[0].has_text
+
+
+def test_mode_strip_rejects_image_processing_options(resources, no_outpdf):
+    """Options requiring rasterization/OCR are rejected in strip mode."""
+    with pytest.raises(BadArgsError, match=r'--deskew'):
+        run_ocrmypdf_api(
+            resources / 'graph_ocred.pdf', no_outpdf, '--mode', 'strip', '--deskew'
+        )