The selection of medium whether it's a written version or a visual image, affect your understanding of the theme. The written version medium could give a more detailed description of the theme rather than the visual image. However, it still depends on your knowledge of the theme. If you have much knowledge of the theme, thus it will not be a problem to understand the theme in both of the medium.
The selection of the medium affects our understanding by giving us details of an image we see in our text when we read the written version we compare the visual version to what we know from reading the written version.
