i did read images using opencv, then i had to make my own transform functions. Then i used transforms.ToTensor()  It worked pretty well for me. thanks again !!! 
class resize_rescale():
def init(self, output_size):
assert isinstance(output_size, int)
self.output_size = output_size
def __call__(self, img):         
    img = cv2.resize(img, (self.output_size, self.output_size)) #(width, height)
    return img

dataset = siamese_dataset(att_faces_dataset,
transform = transforms.Compose([resize_rescale(224), transforms.ToTensor(),
transforms.Normalize(mean=[0.485, 0.456, 0.406],
std=[0.229, 0.224, 0.225])]))