Start project - Build a tool that generates png files combined with two images files.

Hi, I need one penetration tester. I have big project that will cost [login to view URL] project is for starter project, test project Very simple little task cost: 50USD. You should make one png file from two images with same size. On Png file, it should embed code, so at first time, first image should show. but from some exact time, second image should replace to show. And it should not be detected by malware systems. It will lead to long-term projects, because I have been hired by security team, and they know me penetration tester, I will give all tasks from my company to you, if you work well. LONG-TERM PROJECT, cheers!