see if this is what you want, and this

for example, we have figure A, figure B, and figure An is a very small blurred picture. Figure B is the original picture with larger volume. When the loading of picture B completes the trigger event, replace figure A with figure B

give several references:

1. CDN automatic Compression + program displays how is the effect from blur to clarity when the new version of Zhihu loads the picture? -Tw93's answer
2. Progressive JPEG use Progressive JPEG to enhance user experience