StorageReference childRef2 = [your firebase storage path]
storageRef.child(UserDetails.username+"profilepic.jpg");
                    Bitmap bmp = MediaStore.Images.Media.getBitmap(getContentResolver(), filePath);
                    ByteArrayOutputStream baos = new ByteArrayOutputStream();
                    bmp.compress(Bitmap.CompressFormat.JPEG, 25, baos);
                    byte[] data = baos.toByteArray();
                    //uploading the image
                    UploadTask uploadTask2 = childRef2.putBytes(data);
                    uploadTask2.addOnSuccessListener(new OnSuccessListener<UploadTask.TaskSnapshot>() {
                        @Override
                        public void onSuccess(UploadTask.TaskSnapshot taskSnapshot) {
                            Toast.makeText(Profilepic.this, "Upload successful", Toast.LENGTH_LONG).show();
                        }
                    }).addOnFailureListener(new OnFailureListener() {
                        @Override
                        public void onFailure(@NonNull Exception e) {
                            Toast.makeText(Profilepic.this, "Upload Failed -> " + e, Toast.LENGTH_LONG).show();
                        }
                    });`

只需继续执行上述步骤，它将减小您的图片大小，并将其上传到Firebase上，将图片大小减小至1到2 mb 就像我的经验一样，4mb文件变成了304kb.

just go ahead and do above steps it will reduce your image size and upload it on firebase it reduce the image size upto 1 to 2 mb like on my experience 4mb file became 304kb .

filepath是所选图像的File和File对象. :)

filepath is and File object of your selected image. :)