Pierce's system of signification suggests that images read in a non-linear, spatial manner. Extrapolated from its definition, a sign can still allude to a common image that is already present within the viewer's mind, for example, by seeing smoke, a viewer could read the presence of fire.
On the other hand, it is difficult to say the same for words, and so often, text remains linear and absolute.
However, whilst in some instances text can conclude a work, as in the titles Sally Mann gives to her photographs, it can also open meaning and explore interpretation, a good example being 'Missing House', by Christian Boltanski, the statement-like abruptness in this instance in fact encouraging the viewer to expand interpretations, leading to a poignancy and multitude of imagined images, beyond the power of one single image.
(image from: http://www.chgs.umn.edu/museum/memorials/berlin/nameplaguesa.jpg)