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utils/dataloader.py

+from random import shuffle
+import numpy as np
+import torch
+import torch.nn as nn
+import math
+import torch.nn.functional as F
+from PIL import Image
+from torch.autograd import Variable
+from torch.utils.data import DataLoader
+from torch.utils.data.dataset import Dataset
+from matplotlib.colors import rgb_to_hsv, hsv_to_rgb
+
+MEANS = (104, 117, 123)
+class SSDDataset(Dataset):
+    def __init__(self, train_lines, image_size):
+        super(SSDDataset, self).__init__()
+
+        self.train_lines = train_lines
+        self.train_batches = len(train_lines)
+        self.image_size = image_size
+
+    def __len__(self):
+        return self.train_batches
+
+    def rand(self, a=0, b=1):
+        return np.random.rand() * (b - a) + a
+
+    def get_random_data(self, annotation_line, input_shape, jitter=.3, hue=.1, sat=1.5, val=1.5):
+        """实时数据增强的随机预处理"""
+        line = annotation_line.split()
+        image = Image.open(line[0])
+        iw, ih = image.size
+        h, w = input_shape
+        box = np.array([np.array(list(map(int, box.split(',')))) for box in line[1:]])
+
+        # 调整图片大小
+        new_ar = w / h * self.rand(1 - jitter, 1 + jitter) / self.rand(1 - jitter, 1 + jitter)
+        scale = self.rand(.25, 2)
+        if new_ar < 1:
+            nh = int(scale * h)
+            nw = int(nh * new_ar)
+        else:
+            nw = int(scale * w)
+            nh = int(nw / new_ar)
+        image = image.resize((nw, nh), Image.BICUBIC)
+
+        # 放置图片
+        dx = int(self.rand(0, w - nw))
+        dy = int(self.rand(0, h - nh))
+        new_image = Image.new('RGB', (w, h),
+                              (np.random.randint(0, 255), np.random.randint(0, 255), np.random.randint(0, 255)))
+        new_image.paste(image, (dx, dy))
+        image = new_image
+
+        # 是否翻转图片
+        flip = self.rand() < .5
+        if flip:
+            image = image.transpose(Image.FLIP_LEFT_RIGHT)
+
+        # 色域变换
+        hue = self.rand(-hue, hue)
+        sat = self.rand(1, sat) if self.rand() < .5 else 1 / self.rand(1, sat)
+        val = self.rand(1, val) if self.rand() < .5 else 1 / self.rand(1, val)
+        x = rgb_to_hsv(np.array(image) / 255.)
+        x[..., 0] += hue
+        x[..., 0][x[..., 0] > 1] -= 1
+        x[..., 0][x[..., 0] < 0] += 1
+        x[..., 1] *= sat
+        x[..., 2] *= val
+        x[x > 1] = 1
+        x[x < 0] = 0
+        image_data = hsv_to_rgb(x) * 255  # numpy array, 0 to 1
+
+        # 调整目标框坐标
+        box_data = np.zeros((len(box), 5))
+        if len(box) > 0:
+            np.random.shuffle(box)
+            box[:, [0, 2]] = box[:, [0, 2]] * nw / iw + dx
+            box[:, [1, 3]] = box[:, [1, 3]] * nh / ih + dy
+            if flip:
+                box[:, [0, 2]] = w - box[:, [2, 0]]
+            box[:, 0:2][box[:, 0:2] < 0] = 0
+            box[:, 2][box[:, 2] > w] = w
+            box[:, 3][box[:, 3] > h] = h
+            box_w = box[:, 2] - box[:, 0]
+            box_h = box[:, 3] - box[:, 1]
+            box = box[np.logical_and(box_w > 1, box_h > 1)]  # 保留有效框
+            box_data = np.zeros((len(box), 5))
+            box_data[:len(box)] = box
+        if len(box) == 0:
+            return image_data, []
+
+        if (box_data[:, :4] > 0).any():
+            return image_data, box_data
+        else:
+            return image_data, []
+
+    def __getitem__(self, index):
+        if index == 0:
+            shuffle(self.train_lines)
+        lines = self.train_lines
+        n = self.train_batches
+        index = index % n
+        while True:
+            img, y = self.get_random_data(lines[index], self.image_size[0:2])
+            if len(y)==0:
+                continue
+            boxes = np.array(y[:,:4],dtype=np.float32)
+            boxes[:,0] = boxes[:,0]/self.image_size[1]
+            boxes[:,1] = boxes[:,1]/self.image_size[0]
+            boxes[:,2] = boxes[:,2]/self.image_size[1]
+            boxes[:,3] = boxes[:,3]/self.image_size[0]
+            boxes = np.maximum(np.minimum(boxes,1),0)
+            if ((boxes[:,3]-boxes[:,1])<=0).any() and ((boxes[:,2]-boxes[:,0])<=0).any():
+                continue
+            y = np.concatenate([boxes,y[:,-1:]],axis=-1)
+            index = (index + 1) % n
+            break
+            
+        img = np.array(img, dtype=np.float32)
+        tmp_inp = np.transpose(img-MEANS,(2,0,1))
+        tmp_targets = np.array(y, dtype=np.float32)
+        return tmp_inp, tmp_targets
+
+
+# DataLoader中collate_fn使用
+def ssd_dataset_collate(batch):
+    images = []
+    bboxes = []
+    for img, box in batch:
+        images.append(img)
+        bboxes.append(box)
+    images = np.array(images)
+    bboxes = np.array(bboxes)
+    return images, bboxes
+