在图片周围添加背景从而增加分辨率，而不是拉伸或者压缩

img2 = cv2.imread('image.png')
cons = cv2.copyMakeBorder(img2,30,30,280,280,cv2.BORDER_CONSTANT,value=0)
vis = np.concatenate((cons,img1),axis = 0)
cv2.imwrite('out.png',vis)