EPO Color Patent Drawings: What Changed on 1 October 2025

For most of the European Patent Office’s history the answer to “can we file in colour?” was a polite no — you could send colour, but the Office converted it to black and white before publication, and whatever nuance the colour carried was gone. That changed on 1 October 2025. EPO color patent drawings are now accepted and published as filed, in colour and in greyscale, without conversion. It is a genuinely useful reform for anyone prosecuting in life sciences, materials, imaging or display technology. It also arrived with conditions that are easy to miss, and with an added-matter trap that has nothing to do with aesthetics and everything to do with Article 123(2) EPC.

What Changed: EPO Color Patent Drawings Since October 2025

The reform sits in a Decision of the President of the EPO dated 7 July 2025, published at OJ EPO 2025, A49, with implementing guidance in a Notice at OJ EPO 2025, A57. It entered into force on 1 October 2025 and supersedes the previous decision on the presentation of application documents.

The operative wording amends the presentation requirements so that, when filed by means of electronic communication, drawings “may also be executed in colour or in greyscale, in durable, uniformly thick and well-defined lines, strokes or areas.” Two things are worth pausing on. Greyscale is included, not just colour — which matters for micrographs and gradient shading that used to be flattened into unreadable black. And the old requirement of durable, uniformly thick, well-defined execution survives; colour relaxes the palette, not the draughtsmanship.

The practical change is that processing is now end to end. Previously a colour figure was converted to black and white on its way to publication. Now the colour version is what gets published and what appears on the patent certificate.

• In force: 1 October 2025, for European patent applications and subsequent filings.
• Covers: colour and greyscale drawings alike.
• Channel: electronic filing only.
• Effect: no conversion to black and white for publication or for the certificate.

Rule 46 EPC Is Gone — Where the Drawing Rules Actually Live Now

This is the single most common error in European drawing guidance online, and it predates the colour reform by two years. Rule 46 EPC — “Form of the drawings” — no longer exists. It was deleted, together with Rule 49(3) to (12) EPC, with effect from 1 February 2023, as part of the EPO’s digital-transformation package. The EPO’s own text of Rule 46 EPC now reads simply “(deleted)”.

The substance was not abolished; it was relocated. The detailed presentation requirements moved out of the Implementing Regulations and into a decision of the President, precisely so that they could be updated without the slower Administrative Council route. The colour reform is the first substantial demonstration of why that mattered — it took a Presidential decision, not a treaty-level rule change.

So if a checklist tells you that Rule 46(2) EPC requires drawings in “durable, black, sufficiently dense and dark, uniformly thick and well-defined lines”, it is quoting a rule that was repealed three years ago and a colour prohibition that was lifted last year. Rule 49 EPC survives as the general provision on the presentation of application documents; the specifics are in the President’s decision. Formal compliance is examined by the Receiving Section under Rule 57(i) EPC.

The reason to get this right is not pedantry. If you cite a deleted rule in a response to a formalities communication, you invite an avoidable round of correspondence — and you signal that the file has not been reviewed against current practice.

There is a second-order consequence worth planning for. Because presentation requirements now sit in a Presidential decision rather than in the Implementing Regulations, they can change on a much shorter cycle than practitioners are used to. A drawing standard that took an Administrative Council decision to amend could sit untouched for a decade; one that takes a decision of the President can move in a single Official Journal issue. Firms that maintain internal drawing checklists should treat them as living documents and re-verify them against the current decision each year, rather than inheriting a formatting sheet written against the pre-2023 regime.

The Technical Standard: 300 dpi, Contrast and Electronic Filing

The Decision sets a reproduction standard rather than a file-format checklist. Colour or greyscale drawings “must also be sufficiently rich in contrast and suitable to be clearly displayed at a resolution of 300 dpi.” Read that as a legibility test applied to the worst-case reproduction, not as an invitation to upload a photograph.

Two constraints follow that catch people out. First, colour is available only for documents filed by means of electronic communication — a paper filing does not get colour treatment. Second, contrast is doing real work in that sentence. A figure that distinguishes two components only by adjacent pastel fills may be vivid on a designer’s monitor and indistinguishable at 300 dpi. The safest designs still carry a non-colour cue: hatching, a line weight difference, or a reference numeral.

That last point is worth stating plainly, because it is the difference between a figure that merely looks better and one that is more robust. Colour that is decorative is free. Colour that is load-bearing — where the only way to tell element 12 from element 14 is that one is red — makes your disclosure hostage to reproduction quality. Keep colour as reinforcement, and the figure survives a bad print, a greyscale copy and a translation.

Euro-PCT: Why Your Color Figures May Still Be Converted

Here is the limitation that undoes a lot of filing strategies. The reform is a Presidential decision of the EPO, and the EPO cannot change PCT practice. Colour drawings are not accepted in the PCT international phase. The International Bureau converts them to black and white for international publication, retaining the originals on PATENTSCOPE.

For a Euro-PCT application entering the European phase after 1 October 2025, the EPO will proceed on the basis of the colour drawings only if they are actually available on PATENTSCOPE and the publication cover page indicates that availability. Where that is not the case, European processing continues from the published black-and-white version — regardless of what you originally drew.

The strategic consequence is straightforward. If colour genuinely carries information in your figures, a direct European filing preserves it in a way the PCT route currently cannot guarantee. If you are committed to the PCT route, assume black and white and design the figures so that nothing is lost when the colour is stripped. Our guide to PCT drawing requirements covers the international-phase standards in detail.

This is also a reason to decide the filing route before the draughtsman starts, not after. Re-drawing a figure set to survive greyscale conversion is cheap at the drafting stage and expensive once the priority year is running.

Article 123(2): The Added-Matter Trap Hiding in Color

The most serious risk in the new regime is not formal, it is substantive. Converting an application from colour to black and white, or from black and white to colour, is examined for added matter. Article 123(2) EPC prohibits amendment beyond the content of the application as filed, and a change in how a figure conveys information can cross that line.

The EPO’s Notice accompanying the decision warns applicants against referring to colour-specific features in the description, the claims or the abstract. The reasoning is easy to follow once stated: if the description says “the red layer 12”, and the figure is later reproduced in greyscale, you have a clarity problem at best and an unsupported feature at worst. Conversely, a claim limitation that can only be derived from a colour in a drawing is a fragile limitation.

The safe practice is the one that was always good practice. Describe structure and function in words; let the drawing illustrate what the words already say. Colour should make an existing disclosure easier to read, never supply a feature the text omits.

• Do not use colour names in the description, claims or abstract unless the colour is genuinely part of the invention.
• Do not rely on a colour distinction as the sole support for a claim limitation.
• Do not switch a figure set between colour and monochrome mid-prosecution without an added-matter review.
• Do keep reference numerals and line-based cues so the figure reads correctly in any reproduction.

How EPO Color Patent Drawings Compare With USPTO Practice

The two offices have now diverged, and a portfolio filed in both needs to know it. The default at the USPTO remains monochrome: under 37 CFR 1.84(a)(1), “India ink, or its equivalent that secures solid black lines, must be used for drawings.” Colour is the exception, not a filing option.

To use colour in a US utility or design application, 37 CFR 1.84(a)(2) requires a petition explaining why colour is necessary, accompanied by the fee set in 37 CFR 1.17(h), plus one set of colour drawings if filed through the USPTO patent electronic filing system (three sets otherwise). The specification must also carry the prescribed statement: “The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.”

Photographs are treated separately again. Under 37 CFR 1.84(b), they are not ordinarily permitted and are accepted only where they are the only practicable medium for illustrating the claimed invention — electrophoresis gels, blots, autoradiographs, histological sections and similar biological material being the classic examples.

Design applications add their own layer. 37 CFR 1.152 requires the design to be represented by drawings that comply with 37 CFR 1.84 and include a sufficient number of views to constitute a complete disclosure of the appearance of the design. Appropriate surface shading should show the character or contour of the surfaces, and solid black shading is not permitted except when representing the colour black or colour contrast. Broken lines may show visible environmental structure but not hidden planes and surfaces that cannot be seen through opaque material. For the full US standard, see our breakdown of USPTO drawing requirements under 37 CFR 1.84 and the practical treatment in color patent drawings.

The net effect for a transatlantic filing programme: Europe will publish your colour figure as drawn if you file it electronically; the US will make you justify it, pay for it and say so in the specification. Plan one figure set that satisfies both, and vary only where the value of colour justifies the US petition.

A Pre-Filing Checklist for EPO Color Patent Drawings

Most drawing objections are avoidable with a review that takes minutes. Before you file EPO color patent drawings, work through the following.

1. Confirm the filing is electronic — colour and greyscale are unavailable on paper.
2. View every figure at 300 dpi and in greyscale. If two elements merge, add hatching or a line-weight cue.
3. Check that no reference numeral sits on a fill dark enough to hide it.
4. Search the description, claims and abstract for colour words and remove any that are not genuinely part of the invention.
5. Confirm no claim limitation depends solely on a colour shown in a drawing.
6. For a Euro-PCT case, verify whether colour originals are on PATENTSCOPE and flagged on the publication cover page — if not, design for black and white.
7. If the same figures are going to the USPTO, decide now whether to run the 37 CFR 1.84(a)(2) petition or to prepare a compliant monochrome set.

For the wider European formalities picture beyond colour — sheet layout, numbering and text in figures — see our EPO drawing requirements guide, and our note on patent drawings for software inventions if your figures are flowcharts and block diagrams.

Get EPO Color Patent Drawings Filed Right the First Time

PerspireIP prepares EPO color patent drawings, greyscale figure sets and monochrome equivalents that survive conversion — drawn to the current Presidential decision, not to a rule that was deleted in 2023. We handle EPO, USPTO, PCT and design filings from one figure set wherever the standards allow it. See our patent drawing services or contact our team for a fixed quote on your figure set.

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