你可以在 upload 之后创建一个 cloud-function 来替换原始图像。你可以按照这个示例来得到一些想法。您需要注意存储上传以触发您的功能。

Loading images from firebase storage is very slow, it was taking more than 2sec to show image in my web page. Is there any way to seed up image loading? Will it seed up when give read access to world Like: allow read: if true?

Please guide me, what is the best way to upload and download images from firebase storage? Thanks.

Following is my Storage Rule:

service firebase.storage {
  match /b/test-project-faac7.appspot.com/o {
    match /{allPaths=**} {
      allow read: if request.auth != null;
      allow write: if request.auth != null;
    }
  }
}

Code to get Download Url :

 this.storage.ref(item.imgQuestion).getDownloadURL().then(url => {
    item.imgQuestionUrl = url;
 })

You could create a cloud-function where the image can be compressed after upload and replace the original image. You can follow this sample to get some idea. You will need to watch for storage upload to trigger your functions.