Fast Rendering of Image Mosaics and ASCII Art

Abstract

An image mosaic is an assembly of a large number of small images, usually called tiles, taken from a specific dictionary/codebook. When viewed as a whole, the appearance of a single large image emerges, i.e. each tile approximates a small block of pixels. ASCII art is a related (and older) graphic design technique for producing images from printable characters. Although automatic procedures for both of these visualization schemes have been studied in the past, some are computationally heavy and cannot offer real-time and interactive performance. We propose an algorithm able to reproduce the quality of existing non-photorealistic rendering techniques, in particular ASCII art and image mosaics, obtaining large performance speed-ups. The basic idea is to partition the input image into a rectangular grid and use a decision tree to assign a tile from a pre-determined codebook to each cell. Our implementation can process video streams from webcams in real time and it is suitable for modestly equipped devices. We evaluate our technique by generating the renderings of a variety of images and videos, with good results. The source code of our engine is publicly available.

Preserving Command Line Workflow for a Package Management System Using ASCII DAG Visualization

“…2b shows our depiction of the same graph for comparison. General image to ASCII converters [29,32,45] focus on emulating tone differences across an image and thus are a poor fit for node-link diagrams. Xu et al [53] present an algorithm for converting vector line art to ASCII, but their method requires several minutes to generate an image, which is unacceptable in our workflow.…”

Photo collage-based photograph display system on mobile computing platform

“…They employed genetic feature selection for building an optimized image set and GPU-accelerated pattern searching of CUDA for minimizing computation cost. On the other hand, Markuš et al [22] proposed an image mosaic method that exhibited large performance speed-up by employing a decision tree to decide the most appropriate photo tile using a pre-determined codebook for each cell. Their implementation is capable of processing video streams in real time.…”

Bir Sanat Dalı Olarak Piksel Sanatının Kimlik ve Temsil Sorunları

“…Ekranlarda kullanılabilen renk sayısının kısıtlı olması ve çözünürlüklerin çok düşük olması, belirgin bir grafik tarzı dayatmıştır. Geleneksel sanatlardan kanaviçe ya da mozaik ile kıyaslanabilecek bu tarz (Markus, 2015), önceleri oldukça primitif bir yapıdadır; öyle ki 1970'lere kadar piksel bazı grafik oluşturmak için bir arayüz henüz geliştirilmemiştir. Ancak yıllar içinde, hem teknolojinin gelişmesi ve popülerleşmesi, hem de bu alanda çalışan grafik sanatçılarının deneyim kazanması ile, şartların dayattığı bu tarzın 1980'li yıllara gelindiğinde kendi izleyici kitlesi oluşmaya başlamıştır.…”