使用Python将图片转正方形的两种方法实例代码详解

def trans_square(image):
  r"""Open the image using PIL."""
  image = image.convert('RGB')
  w, h = image.size
  background = Image.new('RGB', size=(max(w, h), max(w, h)), color=(127, 127, 127)) # 创建背景图，颜色值为127
  length = int(abs(w - h) // 2) # 一侧需要填充的长度
  box = (length, 0) if w < h else (0, length) # 粘贴的位置
  background.paste(image, box)
  return background

 def trans_square(image):
  	r"""Open the image using PIL."""
    img = image.convert('RGB')
    img = np.array(img, dtype=np.uint8) # 图片转numpy
    img_h, img_w, img_c = img.shape
    if img_h != img_w:
      long_side = max(img_w, img_h)
      short_side = min(img_w, img_h)
      loc = abs(img_w - img_h) // 2
      img = img.transpose((1, 0, 2)) if img_w < img_h else img # 如果高是长边则换轴，最后再换回来
      background = np.zeros((long_side, long_side, img_c), dtype=np.uint8) # 创建正方形背景
      background[loc: loc + short_side] = img[...] # 数据填充在中间位置
      img = background.transpose((1, 0, 2)) if img_w < img_h else background
    return Image.fromarray(img, 'RGB')

def trans_square(image):
  r"""transform square.
  :return PIL image
  """
  img = transforms.ToTensor()(image)
  C, H, W = img.shape
  pad_1 = int(abs(H - W) // 2) # 一侧填充长度
  pad_2 = int(abs(H - W) - pad_1) # 另一侧填充长度
  img = img.unsqueeze(0) # 加轴
  if H > W:
    img = nn.ZeroPad2d((pad_1, pad_2, 0, 0))(img) # 左右填充，填充值是0
    # img = nn.ConstantPad2d((pad_1, pad_2, 0, 0), 127)(img) # 左右填充，填充值是127
  elif H < W:
    img = nn.ZeroPad2d((0, 0, pad_1, pad_2))(img) # 上下填充，填充值是0
    # img = nn.ConstantPad2d((0, 0, pad_1, pad_2), 127)(img) # 上下填充，填充值是127
  img = img.squeeze(0) # 减轴
  img = transforms.ToPILImage()(img)
  return img

from PIL import Image 
import sys 
#先将 input image 填充为正方形 
def fill_image(image): 
  width, height = image.size   
  #选取长和宽中较大值作为新图片的 
  new_image_length = width if width > height else height   
  #生成新图片[白底] 
  new_image = Image.new(image.mode, (new_image_length, new_image_length), color='white')  #注意这个函数！ 
  #将之前的图粘贴在新图上，居中  
  if width > height:#原图宽大于高，则填充图片的竖直维度 #(x,y)二元组表示粘贴上图相对下图的起始位置,是个坐标点。 
    new_image.paste(image, (0, int((new_image_length - height) / 2))) 
  else: 
    new_image.paste(image, (int((new_image_length - width) / 2),0))   
  return new_image 
def cut_image(image):
  width, height = image.size
  item_width = int(width / 3) 
  box_list = []
  # (left, upper, right, lower)
  for i in range(0,3):
    for j in range(0,3):
      #print((i*item_width,j*item_width,(i+1)*item_width,(j+1)*item_width))
      box = (j*item_width,i*item_width,(j+1)*item_width,(i+1)*item_width)
      box_list.append(box)
  image_list = [image.crop(box) for box in box_list]
  return image_list
#保存 
def save_images(image_list): 
  index = 1  
  for image in image_list: 
    image.save(str(index) + '.png', 'PNG') 
    index += 1 
if __name__ == '__main__': 
  file_path = "***"#填入图片名 
  image = Image.open(file_path)   
  #image.show() 
  image = fill_image(image) 
  image_list = cut_image(image) 
  save_images(image_list)