Negative pixel compensation in a touch sensor panel is disclosed. A method can compensate for a negative pixel effect in touch signal outputs due to poor grounding of an object touching the panel. To do so, the method can include determining at least one bound for a negative pixel compensation factor based on touch signal values, estimating the compensation factor within the determined bound based on the touch signal values that are negative, where the negative values indicate the presence of the negative pixel effect, and applying the estimated compensation factor to the touch signal outputs to compensate the touch signal values for the negative pixel effect.