Gradient colour banding on EGLFS Linux device

[jars121]

G'day,

I'm using a QConicalGradient with an Opacity Mask in my QML-based GUI. On my development machines (Mac OSX and Ubuntu 16.04), this displays perfectly with an unnoticeable transition between colours. However, when I deploy the application to my target device (Embedded Linux on an iMX6-based device), there is very noticeable colour banding on the gradient. I thought this may have been a colour depth issue, but fbset correctly lists the rgba colour depth as 32 bit.

What else do I need to investigate to correct this (and related) colour banding issues on a device, which aren't replicated on different platforms/OSes?

Thanks!