Post-processing software products have a growing importance in the modern film production because of the large amount of 3D content. These software split the production of the final scene into distinct components. Each component can be recalculated on its own if it is necessary thereby avoiding of the costly re-rendering of the whole image. One of these possible components is for example the ambient occlusion which simulates the effect of diffuse illumination. The topic of my thesis is developing of a plugin to the Nuke3D post-processing software, which allows the user to calculate ambient occlusion using screen space methods and then compare their speed and results. It approximates the results of the costly ray tracing methods. Screen Space Ambient Occlusion (SSAO) methods don’t need the concrete data of the geometry; it only uses the depth field, the normal vectors and the camera parameters. Regardless of the complexity of the scene, this effect can be calculated and re-calculated for every frame faster, if it is necessary.