let's see the result here you will see the Timeline will be set for the duration of the sequence and it will show the format of the image here in the Viewer: the format specified here is 1920x1012 pixels and the Project Settings was set with the data of this image which was the first image imported into the project frames 396 to 459 the format was not set as the standard format but you will see it has a new custom format which was identified and automatically created as you are bringing images that are not standard formats 