Woodblock printing as a means for 2.5D and 3D surface evaluation

Baar, Teun; Olen, Melissa; Parraman, Carinna; Ortiz Segovia, Maria

Abstract

Inspired by traditional Chiaroscuro woodblock printing techniques of the 16th century, we explore the use of multicolour impressions produced by relief prints as a means to evaluate the surface rendered with 2.5D and 3D printing technologies. Even though topography and micro-imaging methods can be used to measure surfaces, perceptual quality evaluation from surfaces rendered by additive printing methods is still a challenge. By reducing the dimension from 3D or 2.5D back to 2D, classic methods to measure quality that have already found a correlation with human perception would become available to us.
A traditional relief print is created through the combination of a raised printing surface and the surface qualities of the printing block (end-grain hardwood, chipboard, linoleum, acrylic), which is then inked and printed under great downward pressure. The block surface is manipulated by engraving, cutting and abrasion (traditional tools include sharp V shape or U shaped chisels). In order to obtain a high quality printed image, the inked plate needs to produce a solid and well defined line with uniform colour.
As a benchmark of our idea, we employed different methods to control the modulation of a surface by either carving (laser cutting, CNC engraving) from an existing material (acrylic, wood, model board) or building relief using additive fabrication (Makerbot, Océ 2.5D printer prototype). For print analysis we created a set of two targets generated to test special resolution and edge detail. Following traditional printmaking processes the blocks were inked, and subjected to a high level of downward pressure in a press to create impressions (i.e. the surface is embossed by the physical force). All of the blocks were inked and printed in the same way. Instead of evaluating the quality of the surface rendered by each of the methods directly, we perform the evaluation on the impressions made with the blocks.
Each of the testing blocks was adapted from optical frequency test patterns in order to access special resolution and edge detail in print. The first test target uses the 1951 USAF resolution test chart where groups of three horizontal and vertical lines, referred to as elements, are depicted at varying sizes and orientations. By finding the element with the smallest discernible set of lines, we can indicate the resolution corresponding to a given printing block fabrication method. For the second target we utilised a Zone plate ring pattern with a special frequency up to 2 line pairs per millimeter (LP/mm). Different aspects can be assessed on the impressions such as the density of ink, the uniformity of the surfaces, the sharpness of the edges and the spatial resolution at different angles. For instance, the Modulation Transfer Function (MTF) describing the print accuracy for different frequencies in horizontal, vertical and diagonal directions can be found for each of the methods based on the impressions.
In our paper, we discuss the results of our method with each of the available technologies and the possible extension of our solution for the evaluation of more complex features.

Citation

Baar, T., Olen, M., Parraman, C., & Ortiz Segovia, M. (2015, May). Woodblock printing as a means for 2.5D and 3D surface evaluation. Paper presented at AIC2015 Tokyo

• Presentation Conference Type: Conference Paper (unpublished)
• Conference Name: AIC2015 Tokyo
• Start Date: May 19, 2015
• End Date: May 22, 2015
• Publication Date: May 20, 2015
• Peer Reviewed: Peer Reviewed
• Keywords: chiaroscuro woodblock printing techniques, relief prints, 2.5D and 3D printing technologies, topography, micro-imaging
• Publisher URL: http://aic2015.org/
• Additional Information: Title of Conference or Conference Proceedings : AIC2015