The image rights metadata framework through Schema.org and IPTC now covers copyright fields.
As of 08th November, a web markup is available to embed the copyright on the webpage via Schema.org. This means there are now two mechanisms for image licensors or publishers to provide copyright data that will appear to users in the Image Viewer on Image Search: IPTC and Schema.org.
The benefit of this web markup schema extension is to allow licensors or publishers with images already published on the web to easily update the webpage instead of reprocessing images. For new images being licensed, it would still be recommended to use IPTC so the copyright metadata can "live on" within the image.
The attached note provides context and additional information.
Note on image rights information parity
The idea of the Licensable Badge goes back to a collaboration started in 2017 with Google, when Alfonso Gutierrez was the president of CEPIC.
More information on the CEPIC website
Google’s new licensable images features: Towards a new era in image licensing
Licensable Images Badge (by Alfonso Gutierrez, president of CEPIC 2013-2021)