Update pyocr to use psm_parameter based on tesseract version

src/pyocr/builders.py

@@ -304,8 +304,9 @@ class TextBuilder(BaseBuilder):
 
     def __init__(self, tesseract_layout=3, cuneiform_dotmatrix=False,
                  cuneiform_fax=False, cuneiform_singlecolumn=False):
+        from .tesseract import psm_parameter
+        tess_flags = [psm_parameter(), str(tesseract_layout)]
         file_ext = ["txt"]
-        tess_flags = ["-psm", str(tesseract_layout)]
         cun_args = ["-f", "text"]
         # Add custom cuneiform parameters if needed
         for par, arg in [(cuneiform_dotmatrix, "--dotmatrix"),
@@ -561,8 +562,9 @@ class WordBoxBuilder(BaseBuilder):
     """
 
     def __init__(self, tesseract_layout=1):
+        from .tesseract import psm_parameter
+        tess_flags = [psm_parameter(), str(tesseract_layout)]
         file_ext = ["html", "hocr"]
-        tess_flags = ["-psm", str(tesseract_layout)]
         tess_conf = ["hocr"]
         cun_args = ["-f", "hocr"]
         super(WordBoxBuilder, self).__init__(file_ext, tess_flags, tess_conf,
@@ -637,8 +639,9 @@ class LineBoxBuilder(BaseBuilder):
     """
 
     def __init__(self, tesseract_layout=1):
+        from .tesseract import psm_parameter
+        tess_flags = [psm_parameter(), str(tesseract_layout)]
         file_ext = ["html", "hocr"]
-        tess_flags = ["-psm", str(tesseract_layout)]
         tess_conf = ["hocr"]
         cun_args = ["-f", "hocr"]
         super(LineBoxBuilder, self).__init__(file_ext, tess_flags, tess_conf,

src/pyocr/tesseract.py

@@ -161,6 +161,12 @@ def can_detect_orientation():
     )
 
 
+def psm_parameter():
+    """Return the psm option string depending on the Tesseract version."""
+    version = get_version()
+    return "--psm" if version[0] > 3 else "-psm"
+
+
 def detect_orientation(image, lang=None):
     """
     Arguments:
@@ -178,7 +184,7 @@ def detect_orientation(image, lang=None):
     """
     _set_environment()
     with temp_dir() as tmpdir:
-        command = [TESSERACT_CMD, "input.bmp", 'stdout', "-psm", "0"]
+        command = [TESSERACT_CMD, "input.bmp", 'stdout', psm_parameter(), "0"]
         version = get_version()
         if version[0] >= 4:
             # XXX: temporary fix to remove once Tesseract 4 is stable