TVP5151: what impact can be seen when ADC resolution change from 10bit to 9bit?

Hello,

My customer uses a video decoder with internal 10bit ADC. On their system, input is composite signal, output is 8bits.

If video decoder change to other video decoder with internal 9bit ADC, what impact on image can be seen from above device? 

Now TI doesn't provide an EVM of the TVP5151, they cannot evaluate before design. So please give your comment and advise.

Best regards,

Katsu