19/04/2017 · The image compression must be done on the "onload" event of the image created from the uploaded file so the compression function actually has something complete to compress. Because this event happens asynchronously, the upload from the control begins prior to the onload event firing. Once the image is compressed, saving it back to the args.get_fileInputField().files array has no effect So, I have configured the core image field to automatically scale down the images to 1024x1024. This significantly reduces the file size. Are there any other ways to automatically reduce the size of uploaded images? Please note that I am talking about the original files, not image styles.