经过base64转码后的图片，转化为PixelMap并进行压缩，分享出去的小程序缩略图会变得模糊不清，但是如果不压缩，或者压缩不够的话就提示无法分享，
请问这有什么好的解决方案吗？
let imagePackerApi = image.createImagePacker();
let packOpts: image.PackingOption = { format: "image/png", quality: 100 }
if (shareBean.thumData && !StrUtil.isEmpty(shareBean.thumData)) {

  ImageUtilStaticLibrary.base64ToPixelMap(shareBean.thumData).then(async (result) => {
    let thumbBuffer = new ArrayBuffer(1024 * 1024 * 5);
    thumbBuffer = await CEMBImageUtility.compressedImage(result, 64, packOpts)
    mediaMessage.thumbData = new Uint8Array(thumbBuffer)

    const req = new wxopensdk.SendMessageToWXReq()
    req.scene = shareScene == 0 ? this.wxChatScene : this.wxFriendsScene
    req.message = mediaMessage
    let finished = await wxopensdk.WXAPIFactory.createWXAPI(CommonConstants.WX_APP_ID)
      .sendReq(getContext(this) as common.UIAbilityContext, req)
    if (!finished) {
      CEMBAppDialogUtility.showFeedBackDialog("提示", "您目前的微信版本过低或未安装微信，需要安装微信才能使用")
    }
  })
}