Downsampling video coding, whereby downsampled frames are encoded, provides improved perceptual quality in rate-constrained situations. This method shows considerable advantages over other approaches, particularly in wide-spreading high-definition video formats. This paper provides a comprehensive analysis of downsampling video coding. The study proposes a spatially scalable rate-distortion (RD) model, comprising quantization-distortion and quantization-rate models, and develops an optimal encoding frame size determination framework. The proposed method achieves a gain up to 2.3 dB peak signal-to-noise ratio (PSNR) at 1 Mb/s when compared with conventional full frame size coding. The RD performance is close to the optimal scenario, in which the ideal frame size is obtained by heuristically performing downsampling coding in various allowable sizes.

This paper proposes an image-based painterly rendering algorithm for automatically synthesizing an image with color ink diffusion. We suggest a mathematical model with a physical base to simulate the phenomenon of color colloidal ink diffusing into absorbent paper. Our algorithm contains three main parts: a feature extraction phase, a Kubelka-Munk (KM) color mixing phase, and a color ink diffusion synthesis phase. In the feature extraction phase, the information of the reference image is simplified by luminance division and color segmentation. In the color mixing phase, the KM theory is employed to approximate the result when one pigment is painted upon another pigment layer. Then, in the color ink diffusion synthesis phase, the physically-based model that we propose is employed to simulate the result of color ink diffusion in absorbent paper using a texture synthesis technique. Our image-based ink diffusing rendering (IBCIDR) algorithm eliminates the drawback of conventional Chinese ink simulations, which are limited to the black ink domain, and our approach demonstrates that, without using any strokes, a color image can be automatically converted to the diffused ink style with a visually pleasing appearance.