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Leptonica: classes are better

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This commit is contained in:
James R. Barlow
2016-02-08 15:14:44 -08:00
parent 2e6879ee51
commit 4ceb59215f
2 changed files with 43 additions and 94 deletions
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ocrmypdf/leptonica.py
+42 -93
View File
@@ -84,16 +84,34 @@ class LeptonicaIOError(LeptonicaError):
class Pix:
def __init__(self, cpix):
self.cpix = ffi.gc(cpix, _pix_destroy)
self.cpix = ffi.gc(cpix, Pix._pix_destroy)
def __repr__(self):
if self.cpix:
s = "<leptonica.Pix image size={0}x{1} depth={2} at 0x{3:x}>"
return s.format(self.cpix.w, self.cpix.h, self.cpix.d,
int(ffi.cast("intptr_t", self.cpix)))
else:
return "<leptonica.Pix image NULL>"
@classmethod
def read(cls, filename):
"""Load an image file into a PIX object.
Leptonica can load TIFF, PNM (PBM, PGM, PPM), PNG, and JPEG. If
loading fails then the object will wrap a C null pointer.
"""
with LeptonicaErrorTrap():
return cls(lept.pixRead(
filename.encode(sys.getfilesystemencoding())))
def write_implied_format(
self, filename, jpeg_quality=0, jpeg_progressive=0):
"""Write pix to the filename, with the extension indicating format.
jpeg_quality -- quality (iff JPEG; 1 - 100, 0 for default)
jpeg_progressive -- (iff JPEG; 0 for baseline seq., 1 for progressive)
"""
fileroot, extension = os.path.splitext(filename)
fix_pnm = False
if extension.lower() in ('.pbm', '.pgm', '.ppm'):
@@ -112,9 +130,19 @@ class Pix:
move(filename, filename[:-4]) # Remove .pnm suffix
def deskew(self, reduction_factor=0):
return Pix(lept.pixDeskew(self.cpix, reduction_factor))
"""Returns the deskewed pix object.
A clone of the original is returned when the algorithm cannot find a
skew angle with sufficient confidence.
reduction_factor -- amount to downsample (0 for default) when searching
for skew angle
"""
with LeptonicaErrorTrap():
return Pix(lept.pixDeskew(self.cpix, reduction_factor))
def scale(self, scalex, scaley):
"Returns the pix object rescaled according to the proportions given."
with LeptonicaErrorTrap():
return Pix(lept.pixScale(self.cpix, scalex, scaley))
@@ -123,6 +151,10 @@ class Pix:
return Pix(lept.pixRotate180(ffi.NULL, self.cpix))
def find_skew(self):
"""Returns a tuple (deskew angle in degrees, confidence value).
Returns (None, None) if no angle is available.
"""
with LeptonicaErrorTrap():
angle = ffi.new('float *', 0.0)
confidence = ffi.new('float *', 0.0)
@@ -140,85 +172,11 @@ class Pix:
raise LeptonicaError("Correlation failed")
return correlation[0]
def _pix_destroy(pix):
ptr_to_pix = ffi.new('PIX **', pix)
lept.pixDestroy(ptr_to_pix)
print('pix destroy ' + repr(pix))
def pixRead(filename):
"""Load an image file into a PIX object.
Leptonica can load TIFF, PNM (PBM, PGM, PPM), PNG, and JPEG. If loading
fails then the object will wrap a C null pointer.
"""
with LeptonicaErrorTrap():
pix = lept.pixRead(filename.encode(sys.getfilesystemencoding()))
return ffi.gc(pix, _pix_destroy)
def pixScale(pix, scalex, scaley):
"""Returns the pix object rescaled according to the proportions given."""
with LeptonicaErrorTrap():
return lept.pixScale(pix, scalex, scaley)
def pixDeskew(pix, reduction_factor=0):
"""Returns the deskewed pix object.
A clone of the original is returned when the algorithm cannot find a skew
angle with sufficient confidence.
reduction_factor -- amount to downsample (0 for default) when searching
for skew angle
"""
with LeptonicaErrorTrap():
deskewed = lept.pixDeskew(pix, reduction_factor)
return ffi.gc(deskewed, _pix_destroy)
def pixFindSkew(pix):
"""Returns a tuple (deskew angle in degrees, confidence value).
Returns (None, None) if no angle is available.
"""
with LeptonicaErrorTrap():
angle = ffi.new('float *', 0.0)
confidence = ffi.new('float *', 0.0)
result = lept.pixFindSkew(pix, angle, confidence)
if result == 0:
return (angle[0], confidence[0])
else:
return (None, None)
def pixWriteImpliedFormat(filename, pix, jpeg_quality=0, jpeg_progressive=0):
"""Write pix to the filename, with the extension indicating format.
jpeg_quality -- quality (iff JPEG; 1 - 100, 0 for default)
jpeg_progressive -- (iff JPEG; 0 for baseline seq., 1 for progressive)
"""
fileroot, extension = os.path.splitext(filename)
fix_pnm = False
if extension.lower() in ('.pbm', '.pgm', '.ppm'):
# Leptonica does not process handle these extensions correctly, but
# does handle .pnm correctly. Add another .pnm suffix.
filename += '.pnm'
fix_pnm = True
with LeptonicaErrorTrap():
lept.pixWriteImpliedFormat(
filename.encode(sys.getfilesystemencoding()),
pix, jpeg_quality, jpeg_progressive)
if fix_pnm:
from shutil import move
move(filename, filename[:-4]) # Remove .pnm suffix
@staticmethod
def _pix_destroy(pix):
ptr_to_pix = ffi.new('PIX **', pix)
lept.pixDestroy(ptr_to_pix)
print('pix destroy ' + repr(pix))
def getLeptonicaVersion():
@@ -227,14 +185,13 @@ def getLeptonicaVersion():
Caveat: Leptonica expects the caller to free this memory. We don't,
since that would involve binding to libc to access libc.free(),
a pointless effort to reclaim 100 bytes of memory.
"""
return ffi.string(lept.getLeptonicaVersion()).decode()
def deskew(infile, outfile, dpi):
try:
pix_source = pixRead(infile)
pix_source = Pix.read(infile)
print(repr(pix_source))
except LeptonicaIOError:
raise LeptonicaIOError("Failed to open file: %s" % infile)
@@ -243,23 +200,15 @@ def deskew(infile, outfile, dpi):
reduction_factor = 1 # Don't downsample too much if DPI is already low
else:
reduction_factor = 0 # Use default
pix_deskewed = pixDeskew(pix_source, reduction_factor)
pix_deskewed = pix_source.deskew(reduction_factor)
print(repr(pix_deskewed))
try:
pixWriteImpliedFormat(outfile, pix_deskewed)
pix_deskewed.write_implied_format(outfile)
except LeptonicaIOError:
raise LeptonicaIOError("Failed to open destination file: %s" % outfile)
def correlation_binary(pix1, pix2):
correlation = ffi.new('float *', 0.0)
result = lept.pixCorrelationBinary(pix1, pix2, correlation)
if result != 0:
raise LeptonicaError("Correlation failed")
return correlation[0]
if __name__ == '__main__':
parser = argparse.ArgumentParser(
description="Python wrapper to access Leptonica")
tests/test_main.py
+1 -1
View File
@@ -262,7 +262,7 @@ def test_autorotate(spoof_tesseract_cache, renderer):
pix_ref = leptonica.Pix.read(_outfile('reference.png'))
pix_ref_180 = pix_ref.rotate180()
correlation = leptonica.correlation_binary(pix_ref.cpix, pix_ref_180.cpix)
correlation = leptonica.Pix.correlation_binary(pix_ref, pix_ref_180)
assert correlation < 0.10
for n in range(1, 4+1):