unwrap: Change 1D unwrapper from float to double.

skimage/exposure/_unwrap_1d.pyx

@@ -6,11 +6,11 @@
 from libc.math cimport M_PI
 
 
-def unwrap_1d(float[::1] image, float[::1] unwrapped_image):
+def unwrap_1d(double[::1] image, double[::1] unwrapped_image):
     '''Phase unwrapping using the naive approach.'''
     cdef:
         Py_ssize_t i
-        float difference
+        double difference
         long periods = 0
     unwrapped_image[0] = image[0]
     for i in range(1, image.shape[0]):

skimage/exposure/unwrap.py

@@ -90,6 +90,8 @@ def unwrap_phase(image, wrap_around=False):
     image_unwrapped = np.empty_like(image, dtype=np.float32, order='C')
 
     if image.ndim == 1:
+        image_not_masked = np.asarray(image, dtype=np.float64, order='C')
+        image_unwrapped = np.empty_like(image, dtype=np.float64, order='C')
         unwrap_1d(image_not_masked, image_unwrapped)
     elif image.ndim == 2:
         image_not_masked = np.asarray(image, dtype=np.float64, order='C')