Environment- This article applies to Instant Access Points and tested in 184.108.40.206
Answer-IAP starting 4.0 supports uploading a customized logo image file to the built-in splash page for the Internal Captive Portal. Image file more than16KB in size is not supported.
Currently it supports following image formats, ".png", ".jpg", ".tif" & ".gif".
Splash page with logo
When any image chosen more than 16KB, it would throw an error as shown below.
Administrator can also delete existing logo and upload a new one at any point as show below.