HTML img 이미지 최적화

<img srcset="img1.png 320w,
             img2.png 480w,
             img3.png 800w"
     sizes="(max-width: 320px) 280px,
            (max-width: 480px) 440px,
            800px"
     src="img.png" alt="메인 이미지">

 <picture>
  <source media="(min-width:650px)" srcset="img_pink_flowers.jpg">
  <source media="(min-width:465px)" srcset="img_white_flower.jpg">
  <img src="img_orange_flowers.jpg" alt="Flowers" style="width:auto;">
</picture>