Form refers to the presentation of the image, The painter Ben Shahn said that form is the shape of content. To name the elements and objects is all formal description has to do. Describing subject matter, critics name what they see and also characterize it. The creator gives us images, the critic gives us words for them. The description of medium involves more than just denominating the technic it also has to discuss the effects that the use of it has on the expression.
Every image is intentionally, or accidentally, situated within a context.
The time in which an image was made and the circumstances in which the creator had to make it, are all important for the description. Even the life style and the social engagements of the creator are part of it. Description deals with facts, but all facts are dependent on theory, so all descriptions are interwoven with interpretation and evaluation.