transparency.png

Author: POV-Ray source code. 2005 version by Daniel G.. 2009 version by Ed g2s. 2019 version by CyberShadow.
License: Creative Commons Attribution-Share Alike 3.0 Unported license
Source: https://en.wikipedia.org/wiki/PNG#/media/File:PNG_transparency_demonstration_1.png

test_chart.png

Author: Acser123
License: Creative Commons Attribution-Share Alike 4.0 International
Source: https://en.wikipedia.org/wiki/File:Color_Checker.pdf

blackout.heic, rainbow.jpg, whiteout.jpg

Author: Aleksi "DDoS" Sapon
License: Attribution-NonCommercial 4.0 International