13. A non-transitory computer readable medium storing instructions thereon which, when executed by a system, cause the system to perform a method comprising: representing a group of document images using a plurality of visualizations that visualize document layout information for the group of document images based on one or more display device characteristics and based on content of the group of documents; and adapting the plurality of visualizations to an available display width by removing one or more visualizations from the plurality of visualizations based on at least two functional values, wherein the plurality of visualizations are adapted to the available display utilizing a layout function to minimize a dissimilarity of each of the plurality of visualizations that fit into the available display, wherein the plurality of visualizations comprises an iconic tree representation of layout features of a document collection, wherein each icon in the iconic tree representation includes a first part that represents a geometric feature of a layout element and a second part that represents a content type of the layout element, and wherein adapting the plurality of visualizations comprises adapting the iconic tree representation by pruning one or more icon subtrees with a non-greedy selection that is based on a ratio determined from a plurality of tree functional values to create a pruned tree, wherein the plurality of tree functional values utilized by the non-greedy selection include, for each subtree, at least a real-valued distortion function value computed from a subtree considered with a real-valued resource function value computed for a width of an iconic representation of the subtree, and wherein the ratio utilized by the non-greedy selection is a ratio of a real-valued resource function value versus a real-valued distortion function value for a subtree.
13. A non-transitory computer readable medium storing instructions thereon which, when executed by a system, cause the system to perform a method comprising: representing a group of document images using a plurality of visualizations that visualize document layout information for the group of document images based on one or more display device characteristics and based on content of the group of documents; and adapting the plurality of visualizations to an available display width by removing one or more visualizations from the plurality of visualizations based on at least two functional values, wherein the plurality of visualizations are adapted to the available display utilizing a layout function to minimize a dissimilarity of each of the plurality of visualizations that fit into the available display, wherein the plurality of visualizations comprises an iconic tree representation of layout features of a document collection, wherein each icon in the iconic tree representation includes a first part that represents a geometric feature of a layout element and a second part that represents a content type of the layout element, and wherein adapting the plurality of visualizations comprises adapting the iconic tree representation by pruning one or more icon subtrees with a non-greedy selection that is based on a ratio determined from a plurality of tree functional values to create a pruned tree, wherein the plurality of tree functional values utilized by the non-greedy selection include, for each subtree, at least a real-valued distortion function value computed from a subtree considered with a real-valued resource function value computed for a width of an iconic representation of the subtree, and wherein the ratio utilized by the non-greedy selection is a ratio of a real-valued resource function value versus a real-valued distortion function value for a subtree. 17. The non-transitory computer readable medium defined in claim 13 wherein adapting the plurality of visualizations to an available display width comprises removing icon trees via a subtree selection based on tree functionals.