Casey Reas's Process Series, Explained

Casey Reas's Process series is a body of generative artworks in which each work is a short English text describing simple machines and how they interact, and software written from that text draws the result on screen, step by step, with no fixed end. Reas developed the core of the series, Process 4 through Process 18, between 2004 and 2010, and documented it in the Process Compendium, a set of prints and a book published in 2010 (REAS.com).

This guide covers the series itself: where it came from, the vocabulary of Forms, Behaviors and Elements it is built on, how the texts relate to the code and the images, and how the works are exhibited and collected. For Reas's wider career, see his artist page. For the programming environment he co-created, see our guide to Processing art.

Key takeaways

• Each Process work is a short text. Reas writes that the text is primary and that software and hardware are "secondary interpretations that can shift over time."
• The series is built from a small vocabulary: a Form (a circle or a line), Behaviors (rules for movement), and Elements that combine one Form with one or more Behaviors.
• Process grew out of {Software} Structures, Reas's Whitney Artport commission, which responded directly to Sol LeWitt's instruction-based wall drawings.
• The Process Compendium (2010) documents Process 4 to Process 18 in two sets of fifteen 50 x 50 cm prints, each print pairing two images from the same text, plus a 128-page catalog.
• Process works are shown as running software, as prints, as installations and as sculpture. The V&A holds the code, CDs and documentation prints for Process 18 (Software 3).

What is Casey Reas's Process series?

The Process series is a set of rule-based drawing systems that Reas states in plain English and then realizes in software. In the introduction to the Process Compendium, Reas describes each software version as "a kinetic drawing machine with a beginning but no defined end." At every step, each Element on the surface updates itself according to its rules, and the image builds from the accumulated marks (Process Compendium).

The work is the system, so no single picture stands for it. Reas's studio site states the premise directly: the artwork "resides in the rules themselves," and any given image is one of countless possible interpretations (REAS.com). The same page describes the series as "one of the most comprehensive articulations of generative art in the early twenty-first century," which is the studio's own assessment.

Process 4, 5 and 6 made their debut as software and related prints in March 2005, in the exhibition Process / Drawing at bitforms gallery in New York (REAS.com).

How did the Process series begin?

The series began with a Whitney Museum of American Art commission. Reas's site says that in 2001, curator Christiane Paul invited him to create {Software} Structures for Artport, the Whitney's online portal for internet and new media art, as a work linking conceptual art to software (REAS.com). The Whitney dates the finished commission to 2004, with a restored version in 2016, and the Process Compendium also gives 2004 as the commission year (Whitney).

{Software} Structures started with a question. On the Whitney's page, Reas says he asked whether "the history of conceptual art" was "relevant to the idea of software as art." He answered it by implementing three of Sol LeWitt's wall drawings in software, then writing three structures of his own: text descriptions of dynamic relations between elements. The project was created by Reas with Jared Tarbell, Robert Hodgin and William Ngan (Whitney).

Those three structures are where the Process numbering starts. A footnote in the Compendium explains that "the first three Process works are named Structure 1, 2, and 3." Reas adds that although Process grew from the Structure works, the two are separate projects (Process Compendium). That is why the main series begins at Process 4.

How does the Process series relate to Sol LeWitt's wall drawings?

Reas names LeWitt as the starting point. In his essay for {Software} Structures, he writes that "a defining factor" in his shift toward written structures "was the work of Sol LeWitt," and describes a LeWitt wall drawing as a set of instructions to be executed on a wall by a draftsperson (Whitney Artport).

The essay also sets out where software departs from the wall. LeWitt, Reas writes, "writes programs for people to execute and interpret rather than for machines," which lets him work in natural language and leave room for interpretation. Reas identifies motion as the difference: a wall drawing stays static once it is drawn, while a software structure can say "when two elements touch, create a new line" (Whitney Artport). Contact between Elements went on to drive Process 4 and Process 18 alike.

His studio site draws the line from one to the other. In LeWitt's work, "the instructions are primary," and Process extends that principle into software, so the artist's role shifts from composing pictures to defining systems (REAS.com). The Whitney made the same connection in its 2018 to 2019 exhibition Programmed: Rules, Codes, and Choreographies in Art, 1965 to 2018, where an installation view lists Reas's {Software} Structure #003 A alongside LeWitt's Five Towers (1986) (Whitney). For the longer history of rule-based art before computers, see A Short History of Generative Art.

What are Element, Form, Behavior and Process?

They are the four terms every Process text is written in. A Form is a shape, a Behavior is a rule for how it moves, an Element is a Form combined with Behaviors, and a Process places Elements in an environment and says how to draw their relationships. Reas's definitions, from his site and the Compendium:

Sources: REAS.com for the Form, Behavior, Element and Process definitions; Process Compendium for the Library.

The whole Library is small. The Compendium lists two Forms, seven Behaviors and five Elements, and the Elements named in the Process texts are defined there (Process Compendium). Element 1, for example, is a circle that moves in a straight line, stays on the surface, changes direction while touching another Element, and moves away from any Element it overlaps.

The range comes from how the Processes combine and render those parts. Process 4 turns contact into lines whose tone encodes distance, with short connections dark and long ones pale. Process 18, at the other end of the arc, connects touching Elements with translucent quadrilaterals whose opacity rises while contact lasts, building toward dense, tessellated fields (REAS.com).

How do the text, the software and the images relate?

The text is the work, the software is one interpretation of it, and each image is one moment from one run of that software. The Compendium states the order plainly: "The software interpretation is secondary to the text." Because the text leaves many decisions open, the programmer must make choices of their own, and the act of translation into code is itself an interpretation (Process Compendium).

The Compendium records who implemented each Process, when, and in what language: Process 4, for example, was implemented by C.E.B. Reas in winter 2005 in C++/OpenGL and Processing (Process Compendium). The catalog also reproduces alternate software interpretations by other programmers (REAS.com).

Hardware ranks lowest. The Compendium says "the hardware is inconsequential and in time it will fail," and that when compatible parts run out, a new system should be acquired and the software modified for it (Process Compendium). Reas's site makes the same point: the instructions endure as the work's essence, while hardware is "fragile and replaceable" (REAS.com). Writing the rules in English also keeps the work readable for people who do not program and lets a Process be enacted through drawing or other means.

What is the Process Compendium?

The Process Compendium 2004 to 2010 is the archive that closes the central arc of the series: two print sets and a catalog. Each set, labeled A and B, holds fifteen C prints, one for every Process work from Process 4 to Process 18. Every print pairs two images generated from the same Process text, so the viewer sees that one text yields different results (REAS.com).

The catalog gives the specifications. Each set is 15 C prints on Fuji Crystal Archive Pearl in a metal box, 50 x 50 cm (19.7 x 19.7 in), in an edition of 8 plus 2 artist's proofs (Process Compendium). In Reas's words, "two static images have been selected from an infinite number of potential variations" for each Process (Process Compendium).

The book is a 128-page softcover published by REAS Studio in Los Angeles in an edition of 500, as the catalog for the exhibition Process Compendium 2004 to 2010 at Gallery [DAM] Berlin, from September 10 to November 3, 2010 (REAS.com publications). It includes the full text, diagrams and images for Process 4 to Process 18, along with alternate software interpretations and time-lapse sequences showing forms accumulating. Reas links a full scan from his publications page, hosted on the Internet Archive (Internet Archive). The V&A also holds a copy in its collection (V&A).

The Compendium title continues. Reas's online index lists later entries, Process Compendium (X-4) through (X-13), dated 2022, 2023 and 2010/2024 (REAS INDEX).

How are Process works shown: prints, live software or installations?

Process works are shown in all three forms, plus sculpture. The catalog gives a typical Process work's medium as "Text, unique custom software, computer, documentation prints," with dimensions variable. The text comes first in that list, the software runs on a computer, and the prints document it (Process Compendium).

The installations take the systems off the monitor. TI (2004) was projected onto circular disks scattered across a floor, and Surface (2009) arranged twenty equilateral triangles as a Dymaxion map, after Buckminster Fuller, with a different iteration of the software on each (REAS.com). Clad (2010), also catalogued as Process 4 (Object 1, 2, 3), is a triptych of glass fiber reinforced concrete objects made with davidclovers (Process Compendium).

Museums collect the software itself. The V&A's record for Process 18 (Software 3), 2010, lists the code, the code saved on CDs, and documentation prints held in a presentation box (V&A). The museum's label explains that each Process work starts as a written text that is then translated into code, and that the resulting software "can be seen as an interpretation" of the original instructions.

How many Process works are there?

Reas does not give a single total on the pages checked for this article, but his records set the outline. The first three Process works are Structure 1, 2 and 3. The Compendium's prints cover Process 4 to Process 18, one print for every Process created by 2010, which makes fifteen (REAS.com).

The numbering continued after the Compendium. Reas's online index lists Process 19 (Software 2) and Process 20 (Software 2), both dated 2014, and Process 21, dated 2025. The same index files 106 entries under the Process category, a count that also includes software versions, prints, installations, objects, Compendium editions and related works such as {Software} Structures (REAS INDEX).

Is Process the same as Processing?

No. Process is Reas's series of artworks; Processing is the open-source programming environment he co-created with Ben Fry in 2001. The two are related: his site says the development of the series coincided with the creation of Processing (REAS.com), and the Compendium credits several implementations to Processing alongside C++ and OpenGL (Process Compendium). The tool's history is in our guide to Processing art.

Which Casey Reas works are in Layer Curation?

Three Reas works appear in Layer Curation, and by his own index only one of them belongs to the Process series. Process 21 is filed under Process, Network F under CENTURY, and Still Life (HSB E) under Atomism (REAS INDEX). The descriptions below come from Layer's artwork pages.

Process 21 (2025) is the highest-numbered Process work in Reas's index, which lists it as custom software running on a computer and screen at a 1:1 aspect ratio (REAS INDEX). Layer describes it as "a delicate web of geometry, slowly sprawling across a black canvas," and as a slow-building composition that "captures the tension between precision and emergence." The curator's note reads: "A generative lattice where form emerges through relation."

Network F (2025) is listed in Reas's index as custom software with digital images, also at a 1:1 aspect ratio (REAS INDEX). Layer's page describes "colorful gradients of geometry" that "stretch outward and interlock" into a web-like lattice. The Network title has a history inside Process: the index lists Network A and Network B (both 2009) as installations of Process 4.

Still Life (HSB E) (2023) belongs to Reas's Atomism category (REAS INDEX). Layer describes it as a study in form and perception that renders "multiple planes of a single icosahedron in quiet, continuous motion," built as a self-operating system that "unfolds without intervention."

For Reas in his own words on emergence, Processing and the problem of preserving digital art as technology changes, read Layer's interview with Casey Reas.

Why do Process works suit a live display?

A Process work is a drawing machine with no defined end, so the most complete way to see it is running. A print shows two moments chosen by the artist, and a video loop shows one recorded pass; the running software keeps producing new states for as long as it is on. In Layer's interview, Reas says that when he watches his work "running live as code, I see things that I've never seen before."

That is the case for living art: code that keeps executing on the wall. The Layer Canvas renders generative works live on its own processor rather than playing back video, on a 1:1 square screen at 2160 x 2160, the same aspect ratio Reas's index gives for Process 21. Reas's own rules for the series point the same way: the text is the work, and hardware is a replaceable host for the software. The Canvas is available to pre-order in the US for $6,999 plus applicable taxes, with a $99 deposit that is fully refundable until the unit ships, expected in mid-2027.

Sources

1. Process, REAS.com (Reas Studio), https://reas.com/process
2. Publications, REAS.com (Reas Studio), https://reas.com/publications
3. Process Compendium 2004–2010 (scan of the 2010 catalog), Casey Reas on the Internet Archive, https://archive.org/details/reas-compendium
4. REAS INDEX: Process category, Reas Studio, https://index.reas.com/?category=Process
5. REAS INDEX: Process 21, Reas Studio, https://index.reas.com/work/?id=rech5czlHbLBHWoCj
6. REAS INDEX: Network F, Reas Studio, https://index.reas.com/work/?id=recklKQ4t4YyeO7Wb
7. REAS INDEX: Still Life (HSB E), Reas Studio, https://index.reas.com/work/?id=recSCZ2aSbW4nWc23
8. Casey Reas: {Software} Structures, Whitney Museum of American Art, https://whitney.org/exhibitions/software-structures
9. {Software} Structures: A text about Software & Art, Casey Reas on Whitney Artport, https://artport.whitney.org/commissions/software-structures/text.html
10. Programmed: Rules, Codes, and Choreographies in Art, 1965–2018, Whitney Museum of American Art, https://whitney.org/exhibitions/programmed
11. Process 18 (Software 3), Victoria and Albert Museum, https://collections.vam.ac.uk/item/O1225404/
12. Process compendium, 2004-2010 (book), Victoria and Albert Museum, https://collections.vam.ac.uk/item/O1617972/
13. Process 21 by Casey Reas, Layer, https://layer.com/artists/reas/artworks/process-21
14. Network F by Casey Reas, Layer, https://layer.com/artists/reas/artworks/network-f
15. Still Life (HSB E) by Casey Reas, Layer, https://layer.com/artists/reas/artworks/still-life-hsb-e
16. In Conversation With Casey Reas, Layer, https://layer.com/artists/reas/interview