Vector Driven 2.5D printing

Research led by Dr Carinna Parraman, Dr Paul O’Dowd, Mikaela Harding, Centre for Fine Print Research, UWE.

The AHRC funded a follow on project to ‘The Development of Novel Injet Inks‘ in 2014 to reflect 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.

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:

1. 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.

2. 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.

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 are the significant qualities of 2.5D printing 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.

Project Outcome: The development of vector based 2.5D print methods for a painting machine


Through recent trends in the application of digitally printed decorative finishes to products, CAD, 3D additive manufacturing and research in material perception, there is a growing interest in the accurate rendering of materials and tangible displays. Although current advances in colour management and inkjet printing has meant that users can take for granted high-quality colour and resolution in their printed images, digital methods for transferring a photographic coloured image from screen to paper is constrained by pixel count, file size, colorimetric conversion between colour spaces and the gamut limits of input and output devices.

This paper considers new approaches to applying alternative colour palettes by using a vector based approach through the application of paint mixtures, towards what could be described as a 2.5D printing method. The objective is to not apply an image to a textured surface, but where texture and colour are integral to the mark, that like a brush, delineates the contours in the image. The paper describes the difference between the way inks and paints are mixed and applied. When transcribing the fluid appearance of a brush stroke, there is a difference between a halftone printed mark and a painted mark. The issue of surface quality is significant to subjective qualities when studying the appearance of ink or paint on paper. The paper provides examples of a range of vector marks that are then transcribed into brush stokes by the painting machine.

Project Outcome: Generation of Texture in Continuous Tone Digital Images


In a digital age where artists and printers are required to learn a wide range of skills, from graphic design to colour science, is it possible to return to a more artistic application of colour, tone and texture with a mechanically printed image using CAD software?

The reproduction of digitally generated works is divided between the onscreen (RGB) representation of colour and a colorimetric translation through an imaging pipeline to a printing device (CMYK). The developers’ goal of inkjet hardware and software is to match printed colour and texture as close as possible to its on screen representation.

The texture in this case is a simulation though contrast, tone and through the illusional properties of halftoning. So far inkjet has not fully addressed the three dimensional rendering of texture. As touch-screen devices develop and evolve to replicate the creative methods of the artist, can an onscreen difference in appearance between a thickly applied paint or watercolour, be replicated in the same way through the printing hardware?

Drawing tablets have made digital imput devices closer to how an artist would intuitively generate the image, so now is it the turn of the digital printer to bring the prints closer to how artists would apply the colour?

The research includes a survey of 19th Century photomechanical methods of low relief continuous tone images, these methods translated a two-dimensional tonal gradation present in the image to a three dimensional model in gelatine. The research moves into the 21st century investigating alternative methods that incorporates vector based software and 3D printing technologies.

Continuous tone digital output using archivally proven printing methods and material


Whilst the primary focus for the creation and preservation of digitally based artwork in hardcopy has relied in recent years on the gradual refinement of digital printing devices, reference points for their development often appear to follow a strictly linear route. To broaden the current possibilities for permanent, accurate digital hardcopy, Thirkell and the Centre for Fine Print Research has been engaged in the re-assessment of some early photomechanical printing processes which were eclipsed by the mainstream printing approaches long before the advent of the digital era.

Thirkell’s paper drew on a three-part methodology surveying printing techniques through historical and current literature, examining actual printed examples and testing findings through practice. The paper re-evaluated the high resolution and archival qualities of three unique 19th century printing processes in the context of current digital practice. Although in mainstream terms such techniques have become redundant, this re-assessment identified and demonstrated valuable principles such as lightfast ink qualities and continuous tone image rendering which has once again renewed currency in the rapidly expanding field of museum quality digital imaging and printing.

As a result of this research a small AHRC grant was awarded to create The Woodburytype Database. A web-based database of all articles in English relating to the process and production of the Woodburytype.

CFPR is only one of three centres in the world who have tried to recreate this process. This process died out in the early C20th but as the only truly continuous tone printing process ever invented has been accepted internationally by companies such as Hewlett Packard, Ricoh and Kodak as a benchmark against which current digital output can be viewed.

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