point of view. The Laplacian goes for the exact solution. Yet, the inverting of the CDF in the Laplacian is also imperfect, as the computed “cumulative density function” is only an approximation of the true CDF, aspect enhanced by the significant number of iterations, which are required to fill the discontinuities. Another point is that the full inversion is possible because the Laplacian uses 1D feature description, thus being less richer than the multi-dimensional one used for the neural version.

Concluding, just by looking at the richness of the two algorithms, the neural style transfer may be grossly perceived as a significant step ahead with respect to the Laplacian counterpart.

Databases {#Sect:Databases}
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For the various experiments undertaken, several databases have been employed. These are either a collection of digitized paintings, either a collection of digital photographs. In the next paragraphs we summarize their main characteristics.

WikiArt database
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The WikiArt is a collection of digitized paintings used to popularize art. It is in continuous expansion, as every day new works of art are added. The version used is the same as in [@Karayev2014] and it contains approximately 80,000 digitized images of fine-art paintings. We note that this version is 