I made a mediaservice.Saving event that will check on already existing media item if the image's width and the new image's width are the same. If not, the save will be rejected and the original image will be kept. The problem is that as soon as the saving event is reached, my old image get replaced in the media folder and I can't go back. This is my code:

protected override void ApplicationStarted(UmbracoApplicationBase umbracoApplication, ApplicationContext applicationContext)
    {
        //when saving something in MEDIA section - before save
        MediaService.Saving += MediaServiceSaving;
    }

    //When saving an image that already existed, this event will check if the image has the same aspect ratio as the previous image and allow replacing the image
    void MediaServiceSaving(IMediaService sender, SaveEventArgs<IMedia> e)
    {
        foreach (var page in e.SavedEntities)
        {
            //getting the image id
            string id = page.Id + "";
            //Checking media item is not new
            if (id != "0")
            {
                //Querying for image location
                string str = "";
                var db = ApplicationContext.Current.DatabaseContext.Database;
                var result = db.Query<string>("SELECT mediaPath FROM cmsMedia WHERE nodeId = " + id + ";");
                foreach (var row in result)
                    str = row;
                //extracting the id from the path
                id = str.Substring(7, 4);
                //getting the name of the images + extension
                string name = str.Substring(str.LastIndexOf('/') + 1);
                //Path to folder containing original image
                string path = HttpContext.Current.Server.MapPath("~/Media");
                string complete = path + "/" + id + "/" + name;

                //check if image needs to be resized by checking if size folders exists
                if (Directory.Exists(path + "/" + id + "/tile/") || Directory.Exists(path + "/" + id + "/carousel/") || Directory.Exists(path + "/" + id + "/product/") ||
                    Directory.Exists(path + "/" + id + "/mobileTile/") || Directory.Exists(path + "/" + id + "/mobileProduct/"))
                {
                    //Check if new image has acceptable aspect ratio
                    //getting previous image's aspect ratio
                    Bitmap bitmap1 = new Bitmap(complete);
                    double initWidth = bitmap1.Width;
                    double initHeight = bitmap1.Height;
                    double initRatio = (initWidth / initHeight);

                    //getting new image's aspect ratio
                    double height = 0;
                    double width = 0;
                    foreach (var prop in page.Properties)
                    {
                        if (prop.Alias == "umbracoHeight")
                            height = Double.Parse(prop.Value.ToString());
                        if (prop.Alias == "umbracoWidth")
                            width = Double.Parse(prop.Value.ToString());
                    }
                    double ratio = width / height;

                    if (initRatio != ratio)
                    {
                        e.CancelOperation(new EventMessage("Error","Aspect ratio not respected. Choose another image", EventMessageType.Error));
                    }
                    else
                        e.Messages.Add(new EventMessage("Success", "Your new image has the same aspect ratio as the previous", EventMessageType.Success));
                }
            }
        }
    }