Often occurs when you use words to describe an activity on a web forum, one whose users typically relate better to photos.
By posting, you have "gotten it (the topic) off of your chest," so to speak. However, other, perhaps, less intelligent forum users - accustomed to photos, instead of words - express their discontent, causing you to feel an obligaton to edit the post, include photos and undergo all the work that might entail
I have a photo debt running on the car forum I use. I described my work on three different car projects, but the wording was too complicated for most of the forum users to grasp and they told me so. Therefore, if I wish to stay in the good graces of the forum, I am in a "photo debt" to them until I provide photos of the projects I described