Vector Driven 2.5D printing
The Centre For Print Research Vector Driven 2.5D printing research, led by Professor Carinna Parraman, Professor Stephen Hoskins and Dr Paul O'Dowd
For over twelve years the Centre for Fine Print Research (CFPR) has conducted significant research into the interface between practioners’ tacit understanding of materials and the latest 3D digital production technologies.
Beginning with a re-appraisal of the 19th century continuous tone printing technologies that influenced the development of colour imaging for the inkjet printing industry, this research is investigating moving beyond the ubiquitious flat inkjet surface to more dynamic textures and surface effects.
The AHRC have funded a follow on project reflecting on the development of texture and colour printing. This project has investigated the relationship between on screen images, the development of colour separation algorithms, and the computer-aided methods for the physical application of paints and inks to paper.
This research departs from traditional methods of colour separation and printing methods, as it incorporates an extra half dimension or 2.5D printing. 2.5D printing connects emerging interests in the technical, creative and physical approaches to practice.
The process explores capturing, modelling and the application of textured marks that emulate the textured appearance of materials. This research was inspired by an AHRC funded study (2004) which investigated printing methods, over layering of inks, and colour mixing approaches that could assist in the development of colour inkjet technology and evolving digital colour printing methods for artists. The project in 2004 looked at how screen printed colour - the newest multi-colour printing and layering process in the 60s and 70s - was used by artists and commercial printers at that time. It also included translucent and opaque inks, multi-layering, the use of white, fluorescent and metallic inks, and different patterns and tones to build up deep, rich and highly colourful prints. This period of graphic printing demonstrated the range of opportunities for both the commercial designer and the fine artist. Whether screen printed colour could be considered as a theoretical model for the development of inkjet in 2004, the conclusions gained at that time highlighted the need to develop alternative approaches to the printing and over layering of colour. Now ten years later, the focus of this project is within a digital context. The investigations into creating complex pictorial compositions rendering colour and texture information by combined print methods present technologists with new challenges: over layering of colour, digital deposition, methods of colour separation, colour measurement and colour appearance. The terminology ‘combined’ is used as the emphasis here is applying colour and texture at the same time; not a printed texture upon which a halftone over-layer is applied.
The research investigates the ability to physically print combined colour and texture onto a 2D substrate. The motivation is to explore human-analogous gestures for the deposition of mediums toward a digital machine capable of physically reproducing painterly styles and to produce visual effects which exploit the character of materials used. Our inspiration is the work of old masters of painting, able to describe great detail with relatively few strokes. In order to perform this task, we have developed a 2.5D printer and the writing of specific software to address the overprinting, layering of colours and colour workflow methods. To develop and investigate such a machine requires data to drive its operation. Based on available resources the digital image has been selected as the research input, from which a software process generates an interpretation as a vector-based composition. Our approach to image segmentation methods of coloured images into stroke based rendering has considered two different image-making routes:
Auto-segmentation – where bitmap based images (bit-for-bit, raster graphics, pixels, points, image, and jpeg) such as photos, screengrabs, and iPad art can be converted to vectors. The algorithm automatically separates the image into coloured layers. The layers are determined by: edge strength, texture direction, x/y pixel adjacency, hue/saturation/ brightness.
Autographic – where vector based graphics (paths, points, handles, anchors, Bézier curves, smooth lines) such as AutoCAD, Illustrator, Freehand, can be exported as vector based images (linework, x-y-z, postscript, svg, animation). Layers, brush dimensions and lengths, characterisation of brush strokes can be maintained and used to drive the painting machine. These two different approaches, methods, hardware and settings are fully explained in two ‘how to’ guides.
In order to establish a robust working methodology, and as we have continued to explore the subject in greater depth, we have found that 2.5D printing has proven to be a highly complex but enthralling subject. In seeking a definition as to what the significant qualities of 2.5D printing are we have looked across a wide range of disciplines including perception, camouflage, art history, design, archaeology and conservation. We have considered the pictorial representation of objects and landscapes, in particular, investigation of painting, drawing and composition methods by artists to ensure pictorial representations of the world are convincing. The novelty here is that the artist can make multiples of the same image, trying different colour-ways or develop variations – as one would proof a print. The difference here is that whilst the process is digitally driven and colours are machine applied, it uses analogue methods and materials to print the image and attempts to emulate the gestural marks of the artist to create a more dynamic composition. Although current advances in colour management and inkjet printing have meant that users can expect high-quality colour and resolution in the printed image, digital methods for transferring a photographic coloured image from screen to paper are constrained by pixel count, file size, colorimetric conversion between colour spaces and the gamut limits of input and output devices.
Through recent trends in the application of digitally printed decorative finishes to products and packaging, computer aided design, additive layer manufacturing and research in material perception, there is a growing interest in the relationship between accurate rendering of texture, materials, tangible displays and the printed artefact.
This research considers alternative approaches to image making and printing that moves from the on-screen representation of images and painting applications, to the physical generation and methods for surface deposition or 2.5D printing. The research investigates the application of new materials and print processes, as an alternative to four-colour separation and halftoning.
This research and the related papers describe two research strands:
- the development of photographic continuous tone prints by varying the depth of pigment to create a surface topology, and
- the application of pigments that emulates a painting method to create a physical textured surface.
Both methods differ from traditional halftone screening in as much they incorporate a vector approach to image construction. In both cases, the objective is not just to apply an image to an extruded or textured surface, but where the relationship of surface deposition and image are integral.
The Development of Novel Inkjet Inks
Awarding body: Arts and Humanities Research Council (AHRC)
Awarded to: Parraman, Carinna
Researcher participants: O’Dowd, Paul
INDUSTRIAL partnerS: Pulse Roll Label Products Ltd
Project duration: 31/07/2014 – 31/07/2015
In 2004, Dr Carinna Parraman undertook an AHRC funded project entitled "Screenprinted colour as a theoretical model for the development of inkjet technology". The Development of Novel Inkjet Inks seeks to build upon and extend the methods developed working in collaboration with Pulse Roll Label Products Ltd, a specialist manufacturer of inks and varnishes for the label printing and the packaging industries.
Carinna has been invited to be on the conference committee for a new conference - within the IS&T/SPIE Electronic Imaging' family' of conferences http://spie.org/x16218.xml The conference aims to build a new community around the area of 2.5D and 3D display and printing technologies.
The chairs of the committee are:
Maria Ortiz (Canon-OCE, Paris, France)
Philipp Urban (TU Darmstadt, Germany)
Jan Allebach (Purdue Univ., United States)
The other confirmed members of the committee are:
Susan Farnand (RIT, United States)
James Ferwerda (RIT, United States)
Andreas Höpe (PTB (Physikalisch Technische Bundesanstalt, Germany)
Carinna Parraman (University of West of England, United Kingdom)
Sabine Süsstrunk (EPFL, Switzerland)
The conference will cover the following topics:
Methods for estimating and measuring distinct material properties
Quality evaluation of 2.5D and 3D soft- and hard-copy reproductions (display and printing)
Methods for material appearance modeling
Methods for measuring perceived material properties such as texture and glossiness
Effects of environmental aspects in material perception (lighting, observers position, printing media
Sensory input (visual, touch, audio) effect in material perception
Saliency of 2.5D and 3D soft- and hard-copy reproductions (display and printing)
Data acquisition methods for different types of material
Softproofing methods for 2.5D and 3D printing
Aesthetic aspects evaluation of 2.5D and 3D soft- and hard-copy reproductions (display and printing)
Models of material difference perception
Models of BRDFs, BTFs and BSSRDFs
And the first conference was held in San Francisco in 2014.