Add more interpolation modes.

py360convert/c2e.py

@@ -12,6 +12,7 @@
     cube_list2h,
     equirect_facetype,
     equirect_uvgrid,
+    mode_to_order,
     sample_cubefaces,
 )
 
@@ -72,12 +73,7 @@ def c2e(
     np.ndarray
         Equirectangular image.
     """
-    if mode == "bilinear":
-        order = 1
-    elif mode == "nearest":
-        order = 0
-    else:
-        raise ValueError(f'Unknown mode "{mode}".')
+    order = mode_to_order(mode)
 
     if cube_format == "horizon":
         if not isinstance(cubemap, np.ndarray):

py360convert/e2c.py

@@ -10,6 +10,7 @@
     cube_h2dice,
     cube_h2dict,
     cube_h2list,
+    mode_to_order,
     sample_equirec,
     uv2coor,
     xyz2uv,
@@ -77,12 +78,7 @@ def e2c(
         squeeze = False
 
     h, w = e_img.shape[:2]
-    if mode == "bilinear":
-        order = 1
-    elif mode == "nearest":
-        order = 0
-    else:
-        raise ValueError(f'Unknown mode: "{mode}".')
+    order = mode_to_order(mode)
 
     xyz = xyzcube(face_w)
     uv = xyz2uv(xyz)

py360convert/e2p.py

@@ -7,6 +7,7 @@
 from .utils import (
     DType,
     InterpolationMode,
+    mode_to_order,
     sample_equirec,
     uv2coor,
     xyz2uv,
@@ -64,12 +65,7 @@ def e2p(
 
     in_rot = np.deg2rad(in_rot_deg)
 
-    if mode == "bilinear":
-        order = 1
-    elif mode == "nearest":
-        order = 0
-    else:
-        raise ValueError(f'Unknown mode: "{mode}".')
+    order = mode_to_order(mode)
 
     u = -u_deg * np.pi / 180
     v = v_deg * np.pi / 180

py360convert/utils.py

@@ -5,11 +5,57 @@
 from numpy.typing import NDArray
 from scipy.ndimage import map_coordinates
 
+_mode_to_order = {
+    "nearest": 0,
+    "linear": 1,
+    "bilinear": 1,
+    "biquadratic": 2,
+    "quadratic": 2,
+    "quad": 2,
+    "bicubic": 3,
+    "cubic": 3,
+    "biquartic": 4,
+    "quartic": 4,
+    "biquintic": 5,
+    "quintic": 5,
+}
+
 CubeFormat = Literal["horizon", "list", "dict", "dice"]
-InterpolationMode = Literal["bilinear", "nearest"]
+InterpolationMode = Literal[
+    "nearest",
+    "linear",
+    "bilinear",
+    "biquadratic",
+    "quadratic",
+    "quad",
+    "bicubic",
+    "cubic",
+    "biquartic",
+    "quartic",
+    "biquintic",
+    "quintic",
+]
 DType = TypeVar("DType", bound=np.generic, covariant=True)
 
 
+def mode_to_order(mode: InterpolationMode) -> int:
+    """Convert a human-friendly interpolation string to integer equivalent.
+
+    Parameters
+    ----------
+    mode: str
+        Human-friendly interpolation string.
+
+    Returns
+    -------
+    The order of the spline interpolation
+    """
+    try:
+        return _mode_to_order[mode.lower()]
+    except KeyError:
+        raise ValueError(f'Unknown mode "{mode}".') from None
+
+
 def xyzcube(face_w: int) -> NDArray[np.float32]:
     """
     Return the xyz coordinates of the unit cube in [F R B L U D] format.