Structure-Aware Halftoning Using the Iterative Method Controlling the Dot Placement

Abstract

Many image reproduction devices, such as printers, are limited to only a few numbers of printing inks. Halftoning, which is the process to convert a continuous-tone image into a binary one, is, therefore, an essential part of printing. An iterative halftoning method, called Iterative Halftoning Method Controlling the Dot Placement (IMCDP), which has already been studied by research scholars, generally results in halftones of good quality. In this paper, we propose a structure-based alternative to this algorithm that improves the halftone image quality in terms of sharpness, structural similarity, and tone preservation. By employing appropriate symmetrical and non-symmetrical Gaussian filters inside the proposed halftoning method, it is possible to adaptively change the degree of sharpening in different parts of the continuous-tone image. This is done by identifying a dominant line in the neighborhood of each pixel in the original image, utilizing the Hough Transform, and aligning the dots along the dominant line. The objective and subjective quality assessments verify that the proposed structure-based method not only results in sharper halftones, giving more three-dimensional impression, but also improves the structural similarity and tone preservation. The adaptive nature of the proposed halftoning method makes it an appropriate algorithm to be further developed to a 3D halftoning method, which could be adapted to different parts of a 3D object by exploiting both the structure of the images being mapped and the 3D geometrical structure of the underlying printed surface.

Estimation of Motion Sickness in Automated Vehicles using Stereoscopic Visual Simulation

“…In our previous work, we used the local orientation of pixels to develop a structure-aware halftoning method based on IMCDP [21]. It has been shown that the structure-aware version of the IMCDP reproduces sharper halftones and better preserves the tone and structure similarity of the input image.…”

“…Abedini et al used the local orientations of the original image to align the halftone structure with the dominant line in each neighborhood. Their proposed structure-aware halftoning reproduces sharper halftones, while better preserves tonal and structural similarities compared to its non-structure-aware version [21]. Not all the proposed structure-aware halftoning methods have been tested on color images.…”

“…In this paper, we aim to improve the recently proposed monochromatic structure-aware IMCDP [21] by introducing a faster and more stable approach for extracting the local orientations, extend it to color halftoning by investigating the effect of running an independent or dependent halftoning over each colorant channel, and improve its flexibility by proposing an adaptive sharpness enhancement across the image.…”

“…Halftoning techniques have gone through different improvements by supplementing the halftoning algorithm with supplemental information about the original image content to better preserve tonal and structural resemblance to the original continuous-tone input image [12][13][14][15][16][17][18][19][20][21]. As these techniques are aware of details and structures of the original image, they are referred to as structure-aware or structure-based halftoning.…”

“…It is an extension of the IMCDP halftoning algorithm, which reproduces well-formed halftone structures with the possibility of changing the halftone's shape and structure. The achromatic structure-aware IMCDP was recently proposed as a structure-aware halftoning algorithm that improves the sharpness of the halftone image and simultaneously better preserves the tone and structure similarity compared to the original IMCDP [21]. However, the preprocessing step of the algorithm was slow, and it has been applied only to monochrome images.…”