The source JPEG images used in the comparison tests are by Keith Martin. They may be used for private and public test purposes, but you must contact me if you want to use them for display use not related to software or hardware tests or experiments. They are available in both equirectangular and cubeface formats.
Large:
8000x4000px equirectangular JPEG - 2.9MB
2309px cubeface JPEGs (zip archive) - 2.9MB
8000x4000px equirectangular TIFF (zip archive) - 78.4MB
Medium:
6000x3000px equirectangular JPEG - 1.9MB
1732px cubeface JPEGs (zip archive) - 1.9MB
6000x3000px equirectangular TIFF (zip archive) - 44.3MB
Small:
4000x2000px equirectangular JPEG - 956KB
1155px cubeface JPEGs (zip archive) - 980KB
4000x2000px equirectangular TIFF (zip archive) - 19.1MB
Contact Keith by email if you have further questions or if you would like to submit new panorama comparison samples.