diff --git a/tests/test_main.py b/tests/test_main.py
index a08a0dde..4ef299fb 100644
--- a/tests/test_main.py
+++ b/tests/test_main.py
@@ -15,7 +15,6 @@
 # You should have received a copy of the GNU General Public License
 # along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
 
-import logging
 import os
 import shutil
 from math import isclose
@@ -23,15 +22,14 @@ from pathlib import Path
 from subprocess import PIPE, run
 from unittest.mock import patch
 
+import pikepdf
 import PIL
 import pytest
 from PIL import Image
 
 import ocrmypdf
-import pikepdf
 from ocrmypdf.exceptions import ExitCode, MissingDependencyError
 from ocrmypdf.exec import ghostscript, qpdf, tesseract
-from ocrmypdf.leptonica import Pix
 from ocrmypdf.pdfa import file_claims_pdfa
 from ocrmypdf.pdfinfo import Colorspace, Encoding, PdfInfo
 
@@ -61,96 +59,6 @@ def test_quick(spoof_tesseract_cache, resources, outpdf):
     check_ocrmypdf(resources / 'ccitt.pdf', outpdf, env=spoof_tesseract_cache)
 
 
-def test_deskew(spoof_tesseract_noop, resources, outdir):
-    # Run with deskew
-    deskewed_pdf = check_ocrmypdf(
-        resources / 'skew.pdf', outdir / 'skew.pdf', '-d', env=spoof_tesseract_noop
-    )
-
-    # Now render as an image again and use Leptonica to find the skew angle
-    # to confirm that it was deskewed
-    log = logging.getLogger()
-
-    deskewed_png = outdir / 'deskewed.png'
-
-    ghostscript.rasterize_pdf(
-        deskewed_pdf,
-        deskewed_png,
-        xres=150,
-        yres=150,
-        raster_device='pngmono',
-        log=log,
-        pageno=1,
-    )
-
-    pix = Pix.open(deskewed_png)
-    skew_angle, _skew_confidence = pix.find_skew()
-
-    print(skew_angle)
-    assert -0.5 < skew_angle < 0.5, "Deskewing failed"
-
-
-def test_remove_background(spoof_tesseract_noop, resources, outdir):
-    # Ensure the input image does not contain pure white/black
-    with Image.open(resources / 'congress.jpg') as im:
-        assert im.getextrema() != ((0, 255), (0, 255), (0, 255))
-
-    output_pdf = check_ocrmypdf(
-        resources / 'congress.jpg',
-        outdir / 'test_remove_bg.pdf',
-        '--remove-background',
-        '--image-dpi',
-        '150',
-        env=spoof_tesseract_noop,
-    )
-
-    log = logging.getLogger()
-
-    output_png = outdir / 'remove_bg.png'
-
-    ghostscript.rasterize_pdf(
-        output_pdf,
-        output_png,
-        xres=100,
-        yres=100,
-        raster_device='png16m',
-        log=log,
-        pageno=1,
-    )
-
-    # The output image should contain pure white and black
-    with Image.open(output_png) as im:
-        assert im.getextrema() == ((0, 255), (0, 255), (0, 255))
-
-
-# This will run 5 * 2 * 2 = 20 test cases
-@pytest.mark.parametrize(
-    "pdf", ['palette.pdf', 'cmyk.pdf', 'ccitt.pdf', 'jbig2.pdf', 'lichtenstein.pdf']
-)
-@pytest.mark.parametrize("renderer", ['sandwich', 'hocr'])
-@pytest.mark.parametrize("output_type", ['pdf', 'pdfa'])
-def test_exotic_image(
-    spoof_tesseract_cache, pdf, renderer, output_type, resources, outdir
-):
-    outfile = outdir / f'test_{pdf}_{renderer}.pdf'
-    check_ocrmypdf(
-        resources / pdf,
-        outfile,
-        '-dc' if pytest.helpers.have_unpaper() else '-d',
-        '-v',
-        '1',
-        '--output-type',
-        output_type,
-        '--sidecar',
-        '--skip-text',
-        '--pdf-renderer',
-        renderer,
-        env=spoof_tesseract_cache,
-    )
-
-    assert outfile.with_suffix('.pdf.txt').exists()
-
-
 @pytest.mark.parametrize('renderer', RENDERERS)
 def test_oversample(spoof_tesseract_cache, renderer, resources, outpdf):
     oversampled_pdf = check_ocrmypdf(
@@ -442,64 +350,6 @@ def test_algo4(resources, spoof_tesseract_noop, outpdf):
     assert p.returncode == ExitCode.encrypted_pdf
 
 
-@pytest.mark.parametrize('renderer', RENDERERS)
-def test_non_square_resolution(renderer, spoof_tesseract_cache, resources, outpdf):
-    # Confirm input image is non-square resolution
-    in_pageinfo = PdfInfo(resources / 'aspect.pdf')
-    assert in_pageinfo[0].xres != in_pageinfo[0].yres
-
-    check_ocrmypdf(
-        resources / 'aspect.pdf',
-        outpdf,
-        '--pdf-renderer',
-        renderer,
-        env=spoof_tesseract_cache,
-    )
-
-    out_pageinfo = PdfInfo(outpdf)
-
-    # Confirm resolution was kept the same
-    assert in_pageinfo[0].xres == out_pageinfo[0].xres
-    assert in_pageinfo[0].yres == out_pageinfo[0].yres
-
-
-@pytest.mark.parametrize('renderer', RENDERERS)
-def test_convert_to_square_resolution(
-    renderer, spoof_tesseract_cache, resources, outpdf
-):
-    # Confirm input image is non-square resolution
-    in_pageinfo = PdfInfo(resources / 'aspect.pdf')
-    assert in_pageinfo[0].xres != in_pageinfo[0].yres
-
-    # --force-ocr requires means forced conversion to square resolution
-    check_ocrmypdf(
-        resources / 'aspect.pdf',
-        outpdf,
-        '--force-ocr',
-        '--pdf-renderer',
-        renderer,
-        env=spoof_tesseract_cache,
-    )
-
-    out_pageinfo = PdfInfo(outpdf)
-
-    in_p0, out_p0 = in_pageinfo[0], out_pageinfo[0]
-
-    # Resolution show now be equal
-    assert out_p0.xres == out_p0.yres
-
-    # Page size should match input page size
-    assert isclose(in_p0.width_inches, out_p0.width_inches)
-    assert isclose(in_p0.height_inches, out_p0.height_inches)
-
-    # Because we rasterized the page to produce a new image, it should occupy
-    # the entire page
-    out_im_w = out_p0.images[0].width / out_p0.images[0].xres
-    out_im_h = out_p0.images[0].height / out_p0.images[0].yres
-    assert isclose(out_p0.width_inches, out_im_w)
-    assert isclose(out_p0.height_inches, out_im_h)
-
-
 def test_image_to_pdf(spoof_tesseract_noop, resources, outpdf):
     check_ocrmypdf(
         resources / 'crom.png', outpdf, '--image-dpi', '200', env=spoof_tesseract_noop
diff --git a/tests/test_preprocessing.py b/tests/test_preprocessing.py
new file mode 100644
index 00000000..4054e4e4
--- /dev/null
+++ b/tests/test_preprocessing.py
@@ -0,0 +1,185 @@
+# © 2019 James R. Barlow: github.com/jbarlow83
+#
+# This file is part of OCRmyPDF.
+#
+# OCRmyPDF is free software: you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published by
+# the Free Software Foundation, either version 3 of the License, or
+# (at your option) any later version.
+#
+# OCRmyPDF is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with OCRmyPDF.  If not, see <http://www.gnu.org/licenses/>.
+
+import logging
+from math import isclose
+
+import pytest
+from PIL import Image
+
+from ocrmypdf.exec import ghostscript
+from ocrmypdf.leptonica import Pix
+from ocrmypdf.pdfinfo import PdfInfo
+
+# pytest.helpers is dynamic
+# pylint: disable=no-member,redefined-outer-name
+
+check_ocrmypdf = pytest.helpers.check_ocrmypdf
+run_ocrmypdf = pytest.helpers.run_ocrmypdf
+run_ocrmypdf_api = pytest.helpers.run_ocrmypdf_api
+spoof = pytest.helpers.spoof
+
+
+RENDERERS = ['hocr', 'sandwich']
+
+
+def test_deskew(spoof_tesseract_noop, resources, outdir):
+    # Run with deskew
+    deskewed_pdf = check_ocrmypdf(
+        resources / 'skew.pdf', outdir / 'skew.pdf', '-d', env=spoof_tesseract_noop
+    )
+
+    # Now render as an image again and use Leptonica to find the skew angle
+    # to confirm that it was deskewed
+    log = logging.getLogger()
+
+    deskewed_png = outdir / 'deskewed.png'
+
+    ghostscript.rasterize_pdf(
+        deskewed_pdf,
+        deskewed_png,
+        xres=150,
+        yres=150,
+        raster_device='pngmono',
+        log=log,
+        pageno=1,
+    )
+
+    pix = Pix.open(deskewed_png)
+    skew_angle, _skew_confidence = pix.find_skew()
+
+    print(skew_angle)
+    assert -0.5 < skew_angle < 0.5, "Deskewing failed"
+
+
+def test_remove_background(spoof_tesseract_noop, resources, outdir):
+    # Ensure the input image does not contain pure white/black
+    with Image.open(resources / 'congress.jpg') as im:
+        assert im.getextrema() != ((0, 255), (0, 255), (0, 255))
+
+    output_pdf = check_ocrmypdf(
+        resources / 'congress.jpg',
+        outdir / 'test_remove_bg.pdf',
+        '--remove-background',
+        '--image-dpi',
+        '150',
+        env=spoof_tesseract_noop,
+    )
+
+    log = logging.getLogger()
+
+    output_png = outdir / 'remove_bg.png'
+
+    ghostscript.rasterize_pdf(
+        output_pdf,
+        output_png,
+        xres=100,
+        yres=100,
+        raster_device='png16m',
+        log=log,
+        pageno=1,
+    )
+
+    # The output image should contain pure white and black
+    with Image.open(output_png) as im:
+        assert im.getextrema() == ((0, 255), (0, 255), (0, 255))
+
+
+# This will run 5 * 2 * 2 = 20 test cases
+@pytest.mark.parametrize(
+    "pdf", ['palette.pdf', 'cmyk.pdf', 'ccitt.pdf', 'jbig2.pdf', 'lichtenstein.pdf']
+)
+@pytest.mark.parametrize("renderer", ['sandwich', 'hocr'])
+@pytest.mark.parametrize("output_type", ['pdf', 'pdfa'])
+def test_exotic_image(
+    spoof_tesseract_cache, pdf, renderer, output_type, resources, outdir
+):
+    outfile = outdir / f'test_{pdf}_{renderer}.pdf'
+    check_ocrmypdf(
+        resources / pdf,
+        outfile,
+        '-dc' if pytest.helpers.have_unpaper() else '-d',
+        '-v',
+        '1',
+        '--output-type',
+        output_type,
+        '--sidecar',
+        '--skip-text',
+        '--pdf-renderer',
+        renderer,
+        env=spoof_tesseract_cache,
+    )
+
+    assert outfile.with_suffix('.pdf.txt').exists()
+
+
+@pytest.mark.parametrize('renderer', RENDERERS)
+def test_non_square_resolution(renderer, spoof_tesseract_cache, resources, outpdf):
+    # Confirm input image is non-square resolution
+    in_pageinfo = PdfInfo(resources / 'aspect.pdf')
+    assert in_pageinfo[0].xres != in_pageinfo[0].yres
+
+    check_ocrmypdf(
+        resources / 'aspect.pdf',
+        outpdf,
+        '--pdf-renderer',
+        renderer,
+        env=spoof_tesseract_cache,
+    )
+
+    out_pageinfo = PdfInfo(outpdf)
+
+    # Confirm resolution was kept the same
+    assert in_pageinfo[0].xres == out_pageinfo[0].xres
+    assert in_pageinfo[0].yres == out_pageinfo[0].yres
+
+
+@pytest.mark.parametrize('renderer', RENDERERS)
+def test_convert_to_square_resolution(
+    renderer, spoof_tesseract_cache, resources, outpdf
+):
+    # Confirm input image is non-square resolution
+    in_pageinfo = PdfInfo(resources / 'aspect.pdf')
+    assert in_pageinfo[0].xres != in_pageinfo[0].yres
+
+    # --force-ocr requires means forced conversion to square resolution
+    check_ocrmypdf(
+        resources / 'aspect.pdf',
+        outpdf,
+        '--force-ocr',
+        '--pdf-renderer',
+        renderer,
+        env=spoof_tesseract_cache,
+    )
+
+    out_pageinfo = PdfInfo(outpdf)
+
+    in_p0, out_p0 = in_pageinfo[0], out_pageinfo[0]
+
+    # Resolution show now be equal
+    assert out_p0.xres == out_p0.yres
+
+    # Page size should match input page size
+    assert isclose(in_p0.width_inches, out_p0.width_inches)
+    assert isclose(in_p0.height_inches, out_p0.height_inches)
+
+    # Because we rasterized the page to produce a new image, it should occupy
+    # the entire page
+    out_im_w = out_p0.images[0].width / out_p0.images[0].xres
+    out_im_h = out_p0.images[0].height / out_p0.images[0].yres
+    assert isclose(out_p0.width_inches, out_im_w)
+    assert isclose(out_p0.height_inches, out_im_h)