1. A method executed by a computer for visualizing data, comprising: receiving, by the computer, an input data set having a plurality of data items; determining, by the computer, a density distribution of the data items to identify groups of the data items having data values within respective predefined ranges; determining, by the computer, relevance factors for the data items, wherein determining the relevance factors comprises comparing data values of the data items to a predefined threshold; applying, by the computer, data thinning processing to identify data items in the input data set to deselect from visualizing in a visualization screen, wherein identifying the data items to deselect from visualizing is based at least on density of the data items and on the relevance factors, and on deselection of attributes of the input data set to reduce a number of the attributes to be visualized, wherein identifying the data items to deselect from visualizing based on the density comprises identifying, to deselect from visualizing, at least one of the groups of the data items with a higher density than another group, wherein identifying the data items to deselect based on the relevance factors comprises deselecting the data items having data values with a predefined relationship with respect to the predefined threshold, wherein the data items with the predefined relationship with respect to the predefined threshold are lower relevance data items; and presenting, by the computer, for display in the visualization screen, the input data set after applying the data thinning processing.