Artistic minimal rendering with lines and blocks

Abstract

Many non-photorealistic rendering techniques exist to produce artistic effects from given images. Inspired by various artists, interesting effects can be produced by using a minimal rendering, where the minimum refers to the number of tones as well as the number and complexity of the primitives used for rendering. Our method is based on various computer vision techniques, and uses a combination of refined lines and blocks (potentially simplified), as well as a small number of tones, to produce abstracted artistic rendering with sufficient elements from the original image. We also considered a variety of methods to produce different artistic styles, such as colour and two-tone drawings, and use semantic information to improve renderings for faces. By changing some intuitive parameters a wide range of visually pleasing results can be produced. Our method is fully automatic. We demonstrate the effectiveness of our method with extensive experiments and a user study.

Use of non-photorealistic rendering and photometric stereo in making bas-reliefs from photographs

“…It closely follows that used in [8,9] for producing pictures, but omits the stage that performs region extraction. To handle features at multiple resolutions, a three level pyramid is created from the input image, and NPR is applied at each level, the results being combined by averaging.…”

“…Then, given a new face photo (converted to monochrome if necessary), we first use NPR to abstract its appearance, and then apply the rest of the pipeline to get the final bas-relief surface. A detailed description of the NPR method we use [8,9] is given in Section 4. The alternative approach of using photometric stereo is given in Section 5.…”

“…They enhance salient shapes, simplify texture features, and suppress unwanted detail in other areas. Motivated by how sculptors abstract appearance, in this paper, we show this can be achieved by use of a non-photorealistic rending (NPR) method [8,9] specifically designed for abstraction of face images. The addition of this abstraction step significantly improves quality compared to our previous results.…”

Watercolour Rendering of Portraits

“…In addition to performing rendering at a higher resolution for the eyes, other elements in the processing can ensure accuracy. For instance, in [20] morphological cleaning of lines was uniformly applied to remove clutter and noise. However, the size threshold for cleaning was reduced for the eye regions to avoid the possibility of removing critical detail.…”

Efficient Circular Thresholding

“…The monochrome method from [33] is adapted to produce artistic colour renderings that both simplify the image (by smoothing and thresholding) and retain and enhance salient detail by overlaying both black and white lines. The lines are extracted using the approach by Kang et al [34] …”