improving darken image

app.py

@@ -2,7 +2,7 @@ import gradio as gr
 import torch
 import torch.nn as nn
 import torchvision.transforms as transforms
-from PIL import Image, ImageEnhance
+from PIL import Image
 
 norm_layer = nn.InstanceNorm2d
 
@@ -117,9 +117,18 @@ def predict(input_img, ver):
             drawing = model1(input_img)[0].detach()
 
     drawing = transforms.ToPILImage()(drawing)
-    enhancer = ImageEnhance.Brightness(drawing)
-    factor = 0.6  # darkens the image
-    im_output = enhancer.enhance(factor)
+
+    # Making image darker
+    source = drawing.split()
+
+    R, G, B = 0, 1, 2
+    constant = 2  # constant by which each pixel is divided
+
+    Red = source[R].point(lambda i: i < 150 & i / constant)
+    Green = source[G].point(lambda i: i < 150 & i / constant)
+    Blue = source[B].point(lambda i: i < 150 & i / constant)
+
+    im = Image.merge(im.mode, (Red, Green, Blue))
     return im_output