Changing my input image resolution for my neural network

Hello! I am training a neural network and my dataset is in COCO format. Now I would like to change my input images’ resolution to a smaller one since my resources in terms of memory is only limited. I tried using cv2.resize but it does not work. Can anyone suggest any ways to achieve what I want? by the way here is my code loading my images

import os
import cv2
import torch
import torchvision
from PIL import Image
from pycocotools.coco import COCO

class myOwnDataset(
    IMG_SIZE = 100

    def __init__(self, root, annotation, transforms=None):
        self.root = root
        self.transforms = transforms
        self.coco = COCO(annotation)
        self.ids = list(sorted(self.coco.imgs.keys()))

    def __getitem__(self, index):
        # Own coco file
        coco = self.coco
        # Image ID
        img_id = self.ids[index]
        # List: get annotation id from coco
        ann_ids = coco.getAnnIds(imgIds=img_id)
        # Dictionary: target coco_annotation file for an image
        coco_annotation = coco.loadAnns(ann_ids)
        # path for input image
        path = coco.loadImgs(img_id)[0]['file_name']
        # open the input image
        img =, path))
        img = cv2.resize(img, (self.IMG_SIZE, self.IMG_SIZE), interpolation = cv2.INTER_AREA)

        # number of objects in the image
        num_objs = len(coco_annotation)

        # Bounding boxes for objects
        # In coco format, bbox = [xmin, ymin, width, height]
        # In pytorch, the input should be [xmin, ymin, xmax, ymax]
        boxes = []
        for i in range(num_objs):
            xmin = coco_annotation[i]['bbox'][0]
            ymin = coco_annotation[i]['bbox'][1]
            xmax = xmin + coco_annotation[i]['bbox'][2]
            ymax = ymin + coco_annotation[i]['bbox'][3]
            boxes.append([xmin, ymin, xmax, ymax])
        boxes = torch.as_tensor(boxes, dtype=torch.float32)
        # Labels (In my case, I only one class: target class or background)
        labels = torch.ones((num_objs,), dtype=torch.int64)
        # Tensorise img_id
        img_id = torch.tensor([img_id])
        # Size of bbox (Rectangular)
        areas = []
        for i in range(num_objs):
        areas = torch.as_tensor(areas, dtype=torch.float32)
        # Iscrowd
        iscrowd = torch.zeros((num_objs,), dtype=torch.int64)

        # Annotation is in dictionary format
        my_annotation = {}
        my_annotation["boxes"] = boxes
        my_annotation["labels"] = labels
        my_annotation["image_id"] = img_id
        my_annotation["area"] = areas
        my_annotation["iscrowd"] = iscrowd

        if self.transforms is not None:
            img = self.transforms(img)

        return img, my_annotation

    def __len__(self):
        return len(self.ids)

# In my case, just added ToTensor
def get_transform():
    custom_transforms = []
    return torchvision.transforms.Compose(custom_transforms)

train_data_dir = '/content/TACO/data'
train_coco = '/content/TACO/data/annotations.json'

# create own Dataset
my_dataset = myOwnDataset(root=train_data_dir,

# collate_fn needs for batch
def collate_fn(batch):
    return tuple(zip(*batch))

# Batch size
train_batch_size = 1

# own DataLoader
data_loader =,

img =…)
img = img.resize((self.IMG_SIZE, self.IMG_SIZE))