feat sketch 提取接口

fix

app/service/image2sketch/util/image_pool.py

@@ -0,0 +1,54 @@
+import random
+import torch
+
+
+class ImagePool():
+    """This class implements an image buffer that stores previously generated images.
+
+    This buffer enables us to update discriminators using a history of generated images
+    rather than the ones produced by the latest generators.
+    """
+
+    def __init__(self, pool_size):
+        """Initialize the ImagePool class
+
+        Parameters:
+            pool_size (int) -- the size of image buffer, if pool_size=0, no buffer will be created
+        """
+        self.pool_size = pool_size
+        if self.pool_size > 0:  # create an empty pool
+            self.num_imgs = 0
+            self.images = []
+
+    def query(self, images):
+        """Return an image from the pool.
+
+        Parameters:
+            images: the latest generated images from the generator
+
+        Returns images from the buffer.
+
+        By 50/100, the buffer will return input images.
+        By 50/100, the buffer will return images previously stored in the buffer,
+        and insert the current images to the buffer.
+        """
+        if self.pool_size == 0:  # if the buffer size is 0, do nothing
+            return images
+        return_images = []
+        for image in images:
+            image = torch.unsqueeze(image.data, 0)
+            if self.num_imgs < self.pool_size:   # if the buffer is not full; keep inserting current images to the buffer
+                self.num_imgs = self.num_imgs + 1
+                self.images.append(image)
+                return_images.append(image)
+            else:
+                p = random.uniform(0, 1)
+                if p > 0.5:  # by 50% chance, the buffer will return a previously stored image, and insert the current image into the buffer
+                    random_id = random.randint(0, self.pool_size - 1)  # randint is inclusive
+                    tmp = self.images[random_id].clone()
+                    self.images[random_id] = image
+                    return_images.append(tmp)
+                else:       # by another 50% chance, the buffer will return the current image
+                    return_images.append(image)
+        return_images = torch.cat(return_images, 0)   # collect all the images and return
+        return return_images