import numpy as np
from PIL import Image

def letterbox_image(image, size):
    iw, ih = image.size
    w, h = size

    scale = min(w / iw, h / ih)
    nw = int(iw * scale)
    nh = int(ih * scale)

    image   = image.resize((nw, nh), Image.BICUBIC)
    new_image = Image.new('RGB', size, (128, 128, 128))
    new_image.paste(image, ((w - nw) // 2, (h - nh) // 2))

    return new_image

def get_classes(classes_path):
    with open(classes_path, encoding='utf-8') as f:
        class_names = f.readlines()
    class_names = [c.strip() for c in class_names]
    return class_names, len(class_names)

def cvtColor(image):
    if len(np.shape(image)) == 3 and np.shape(image)[2] == 3:
        return image 
    else:
        image = image.convert('RGB')
        return image 

def preprocess_input(x):
    x /= 127.5
    x -= 1.
    return x