A former Wollongong High School teacher has been sentenced to 16 months' periodic detention for accessing child pornography images on his home computer.Robert Andrew Dunwoodie was described as an unimpressive witness when he faced Wollongong Local Court this morning for sentencing."The explanations advanced by the defendant were self serving, often inherently improbable, and at times disturbing,'' Magistrate Ian Guy said.The 44-year-old Figtree man had pleaded guilty to knowingly accessing 612 child pornography images between January and June 2008.Dunwoodie will serve all of the 16 months' weekend detention, after which he will be placed on a three-year good behaviour bond.In court last week Dunwoodie said he had suffered depression over several years and became engrossed in adult pornography.During the course of viewing "trillions'' of legal images, Dunwoodie claimed he stumbled upon child pornography."There was a legal site and (it had the word or) something like 'teens', it didn't have anything more than that," he told the court."With my curiosity I opened up several of those."He also conceded that he had tarnished the teaching profession by his actions."I know the girls at Wollongong High School were taken aside and questioned in detail about whether I had sexually assaulted them," he told the court last week."I know the anguish (this has caused) many parents."I'm sorry the teaching profession has been tarnished by me."I was placed in a position of trust and I let that down."For more coverage see Saturday's Mercury.