subjective quality assessment.

The subjective assessment of the generalized perspective projection (parameterized with projection center d) was conducted using eight omnidirectional images, in equirectangular format, taken from the Salient360! dataset [1]. The Stimulus Comparison Adjectival Categorical Judgment (SCACJ) was selected as an evaluation method. More details about generalized perspective projection, rendered viewport images, and the subjective assessment procedure can be found in [2].