Getty Images(Credit: Getty Images)Some of the biggest tech companies in the world served ads on a website featuring images of child abuse, helping to fund its operations. It shines a light into the dark corners of digital advertising.Sometimes you come across an image online that's so horrifying you can't unsee it. For Krzysztof Franaszek, it happened at work.Franaszek runs the advertising research firm Adalytics based in the US. Recently, he was studying where ads for the US Department of Homel...