Add titl-shift effect

hakuimg/tilt_shift/__init__.py

@@ -0,0 +1,15 @@
+import cv2
+from PIL import Image
+
+from .utils import tilt_shift
+
+
+def run(np_img, focus_ratio: float, dof: int):
+    focus_ratio += 5
+
+    height = np_img.shape[0]
+
+    focus_height = round(height * (focus_ratio / 10))
+    np_img = tilt_shift(np_img, dof=dof, focus_height=focus_height)
+
+    return Image.fromarray(np_img)

hakuimg/tilt_shift/utils.py

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+"""
+Original: https://github.com/andrewdcampbell/tilt-shift/
+"""
+import cv2
+import numpy as np
+
+
+def tilt_shift(im, focus_height: int, dof: int = 60):
+    if focus_height < 2*dof:
+        focus_height = 2*dof
+    if focus_height > im.shape[0] - 2*dof:
+        focus_height = im.shape[0] - 2*dof
+
+    above_focus, below_focus = im[:focus_height,:], im[focus_height:,:]
+    above_focus = increasing_blur(above_focus[::-1,...], dof)[::-1,...]
+    below_focus = increasing_blur(below_focus, dof)
+    out = np.vstack((above_focus, below_focus))
+
+    return out
+
+def increasing_blur(im, dof=60):
+    BLEND_WIDTH = dof
+    blur_region = cv2.GaussianBlur(im[dof:,:], ksize=(15,15), sigmaX=0)
+    if blur_region.shape[0] > dof*2:
+        blur_region = increasing_blur(blur_region, dof)
+    blend_col = np.linspace(1.0, 0, num=BLEND_WIDTH)
+    blend_mask = np.tile(blend_col, (im.shape[1], 1)).T
+    res = np.zeros_like(im)
+    res[:dof,:] = im[:dof,:]
+    # alpha blend region of width BLEND_WIDTH to hide seams between blur layers
+    res[dof:dof+BLEND_WIDTH,:] = im[dof:dof+BLEND_WIDTH,:] * blend_mask[:, :, None] + \
+        blur_region[:BLEND_WIDTH,:] * (1-blend_mask[:, :, None])
+    res[dof+BLEND_WIDTH:,:] = blur_region[BLEND_WIDTH:]
+    return res