IPAX: Stop picking colors by eye. Start building robust Color Systems that scale.

1. Designing Color Systems instead of picking colors

A palette is just a list of colors. A Color System*, in a brand book or Design System, defines how those colors behave across interfaces, charts, themes, typography, branding, accessibility, and different devices.

* Note: “Color System” is not a widely established term in current design practice. Most workflows still operate with palettes or design tokens, not system-level color behavior models.

As experienced designers know, designing “by eye” does not scale well. It overlooks situations that only become visible problems later.

IPAX is being developed to help designers, UX and accessibility professionals build more robust Color Systems from the start, with practical tools for communication design, accessibility, and Design Systems.

2. Design practice and accessibility started at odds

While WCAG and APCA can be a valuable foundation for good design, accessibility has usually been positioned as a final audit step, expressed in technical and normative language, and supported by tools that many designers experience as bureaucratic rather than practical.

As a result, accessibility is often avoided until it becomes a formal requirement or a legal obligation.

IPAX is being developed to change where accessibility and ergonomics are positioned in the process. It is designed to support decision-making during design itself, so the resulting systems are not only compliant, but structurally sound: decisions are traceable, consistent, and not dependent on subjective preference or constant negotiation after the fact.

3. From pair checking to system design

Most accessibility models evaluate color in pairs: text against background. WCAG and APCA operate within this unit because it is measurable, consistent, and easy to validate.

The problem is that real Design Systems do not work as a collection of isolated pairs. Once a system grows, colors are reused across multiple contexts, roles, and states. At that point, pair-by-pair validation stops being useful. The number of combinations grows quickly, but more importantly, it does not reflect how designers actually make decisions. Designers do not design all possible combinations. They design systems with roles and constraints.

IPAX is being developed from that reality. Instead of treating color as independent pairs, it structures color as a system: Ink and Paper define the boundaries, Accents operate within that range, and Extended colors exist outside it for controlled use cases.

4. The IPAX Score

IPAX unifies multiple accessibility standards, ergonomic studies and design principles into a single five-point scale. The goal is not to replace WCAG or APCA, but to translate their criteria into an intuitive format that helps designers make better decisions beyond basic compliance.

Scores X to 3 correspond to accessibility compliance.

They indicate whether a pair meets legal and technical thresholds for readability.

Reaching 2 means the design is safe: it passes accessibility requirements. Everything beyond that is an improvement in design quality, not a compliance requirement.

Scores 4 and 5 describe design quality.

They represent combinations that are not only readable, but stable and suitable for sustained use in real interfaces.

High contrast (which WCAG and APCA reward) can improve detectability, but it can also increase visual fatigue, become uncomfortable over time, or fail users with astigmatism or sensitivity to glare.

IPAX introduces penalties for halation, glare and chromatic fatigue, so that scores 4 and 5 reflect not only contrast performance, but also real reading comfort.

An example of accessible design that does not equal good design
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This text box, using black text (#000000) on a bright yellow background (#FFFF00), passes WCAG (AAA, 19.5:1) and APCA (Lc 101), with maximum contrast performance under both models. This sample uses the 15px body text size indicated by the official APCA calculator for this color pair and polarity.

IPAX evaluates this same pair as follows:

APCA base:	5	Meets high perceptual contrast threshold (directional evaluation)
Chromatic fatigue:	-1.4	High saturation stress (cone adaptation + opponent channel load)
Glare:	-0.1	Brightness discomfort under sustained exposure (display emission effect)
Final IPAX score	3.5	Aggregated perceptual adjustment

This places the combination in a clear category: legally compliant, but not universally good design.

( Keep reading to experience for yourself how comfortable or uncomfortable this combination feels in sustained reading, or skip to next chapter » )

For some users (particularly certain low-vision profiles), this combination may genuinely improve readability and detectability. For millions of other users, however, it may introduce discomfort, visual fatigue, glare, chromatic stress, or reduced long-form reading comfort.

This exposes an important historical tension in accessibility: many accessibility requirements have been resisted by designers not necessarily because designers oppose accessibility itself, but because some compliant outcomes are not consistently perceived as good design across different contexts and users.

One of the core hypotheses behind IPAX is that accessibility systems become far more adoptable when they also help produce excellent design outcomes, not only legal compliance.

This leads to another important definition within IPAX, conceived as a practical system for real-world design workflows: excellent design is contextual.

Rather than assuming a single universal visual solution, IPAX treats accessibility as a system of adaptive contexts and themes:
• Light mode
• Dark mode
• Standard contrast conditions
• High contrast conditions

Different users, environments, displays, sensitivities, and tasks may require different perceptual balances between contrast, comfort, hierarchy, fatigue, and readability.

For this reason, IPAX proposes that context itself should become part of accessibility evaluation and design system architecture —not only raw contrast ratios (WCAG) or perceptual polarity calculations (APCA).

However, while adding variables and requirements is technically easy, the industry reality is different: many designers and developers currently experience accessibility as a bureaucratic burden disconnected from actual design practice.

This creates the central challenge IPAX is attempting to solve:

How can accessibility become operationally transparent, with automation carrying the heavy burden, while designers remain focused on what they actually do best: making better design decisions?

IPAX is being developed as an attempt to answer that question.

IPAX therefore does not position itself as a replacement for WCAG or APCA, both of which remain foundational contributions to accessibility research and standardization.

Instead, IPAX attempts to reduce the historical friction between accessibility and design quality: not by lowering standards, but by helping accessibility participate more naturally in how designers already think, structure systems, and make decisions.

This example illustrates a recurring tension in accessibility modeling: WCAG and APCA can both correctly classify a combination as valid, while human perception may signal an overwhelming contrast and even physical discomfort over time. High contrast improves detectability, but it does not fully account for fatigue, glare sensitivity, or chromatic strain under sustained exposure.

The numerical evaluation improves under modern perceptual models (like APCA), yet the lived reading experience still reveals limitations that neither WCAG nor APCA fully capture.

This is not a failure of WCAG or APCA. Both are significant advances in formalizing readability. Rather, it highlights that accessibility metrics describe necessary conditions, not the full space of design quality. IPAX is being developed to explore this gap: the distance between what is measurable as accessible and what is experienced as usable in real design contexts.

One of the core assumptions behind IPAX is that if accessibility systems also reward good design —not only compliance— then designers are more likely to adopt them in practice.

5. From system structure to IPAX

Real design systems do not behave as isolated combinations of colors, so pair-based validation does not scale in practice.

IPAX shifts the unit of design from pairs to system structure. Within each context (such as light or dark mode), two anchors define the system: Ink and Paper. Ink defines the content boundary. Paper defines the surface boundary. Together, they establish the system’s operating range.

Colors that sit between Ink and Paper are treated as Accents. These accents are validated against the anchors, not against each other. This avoids combinatorial checking while preserving consistency across roles and contexts.

In practice, a single accent color rarely performs equally well against both anchors. For this reason, IPAX allows Accent Groups: sets of related colors that serve the same semantic role in different contexts. Each variant is selected based on whether it needs to operate against Ink or against Paper.

Colors outside the Accents range extend beyond Ink–Paper as darker or lighter values (Extended Ink and Extended Paper), and are not part of the Accent system or its validation logic.

This structure allows IPAX to treat color as a system that can be audited, rather than a collection of independent pairs.

Testing the model itself: the Sandbox

As of May 2026, the IPAX penalty coefficients are experimental and under fine tuning. They are informed by research on visual conditions such as astigmatism and presbyopia, and calibrated through applied testing in real design environments.

The platform is being developed as a 'Living Laboratory' where users can test different color combinations and typography in real time.

Conclusion

IPAX is being developed to serve as a pragmatic scale that reflects professional quality in information design. While legal standards are necessary and must continue to advance, the design discipline requires its own internal standard to define professional excellence. By moving from the evaluation of isolated color pairs to the audit of entire systems, IPAX allows for the creation of information environments that stay readable, consistent, and usable over time.