Removing ripples from PWM controlled LED in camera vision application
If you used an inductor (with maybe a capacitor) filter in line with the LEDs you would get much lower ripple voltage on the LEDs. At the moment it sounds like the LEDs are being modulated directly by the PWM frequency and this will generate "beats" with the video frame and line rate. This produces ripples in the same way as aliasing can occur when sampling a frequency that is too high. You could also try increasing the PWM frequency or maybe locking it to the video signal somehow.

Here's a circuit that does this: -



By the way the circuit link doesn't work for me.