What is the test for reversing a finding of not guilty on appeal?

On appeal, we begin with the presumption that the trial court's judgment is correct and supported by substantial evidence. (Marriage of Arceneaux (1990) 51 Cal.3d 1130, 1133.) Consistent with this presumption, we draw all inferences in favor of the judgment unless the record expressly contradicts them. (Ibid.) An appellant must affirmatively demonstrate grounds for reversal because trial court error will not be assumed. (People v. Sullivan (2007) 151 Cal.App.4th 524, 549.)