Structure-preserving NPR framework for image abstraction and stylization

Abstract

This work presents a structure-preserving non-photorealistic rendering (NPR) framework that can produce an effective structure-preserving abstracted and stylized output by manipulating visual features from 2D color image. The proposed framework distills the prominent structural features, dominant edges, medium-scale details, curved discontinued edges, silhouette, dendritic structures and curved boundaries and suppresses the superfluous details like noise, texture, irregular gradients, small-scale details and block artifacts. This framework effectively enhanced the significant image properties such as color, contrast, edge strength and sharpness at every stage based on the obtained statistical features availability information and the predefined conditions. This leads to enhancement of quality assessment features such as PSNR, SSIM and suppressing the image complexity and noise. It considers image and object space information to produce abstraction and stylization, thereby identifying emphasized elements of the structure using Harris feature detector algorithm. The proposed framework effectively preserves the structural features in the foreground of an image by comprehensively integrating the sequence of NPR image filters through rigorous experimental analysis simultaneously diminishing the background content of an image. Implementation of the proposed work is carried out in MATLAB 2018 with high-performance computer of 6.6 teraflop/s computing environment and Nvidia Tesla P100 GPU. The proposed framework evaluates every stage output with various subjective matters and quality assessment techniques with various statistical essences. By this manner, contextual features in an image have been identified and well preserved. Effectiveness of the proposed work has been validated by conducting the experiments taking David Mould dataset and Flickr images as references and comparing the obtained results with similar contemporary work cited in the literature. In addition, user’s visual feedback and the standard quality assessment techniques were also used to evaluate the work. Finally, this work lists out the structures preserving applications, constraints, framework implementation challenges and future work in the fields of image abstraction and stylization.