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Patent Drawings In Colour

Written By Matthew Rodgers Patent Attorney

A patent specification typically consists of a description of the invention, some claims, an abstract and one or more "drawings". Historically, drawings have been limited to black and white line drawings and specifically exclude the use of colour. This is a historical hangover from a time when patent specifications were printed, and the early phases of digitisation of the patent offices did not address the issue for a variety of reasons.

In the mechanical and chemical fields, where devices and chemical structures can be easily illustrated by line drawings, this limitation is not generally a problem; however, in other fields, the inability to use colour figures can make providing a clear disclosure of the invention difficult. It is a particular issue in the biotech field, where complex data sets are difficult, if not impossible, to present without the use of graphs and charts in colour. In many instances, colour photographs are the most appropriate way to illustrate an invention, for example, photomicrographs, gel images, and photographs illustrating particular phenotypes; however, photographic figures present particular problems for the applicant where they must be reduced to black and white and important detail can be lost, as anyone who has tried to present red and green fluorescently stained photomicrographs will immediately appreciate.

Rules relating to the presentation of drawings are relatively consistent. For example, for GB patent applications, rule 14, Sh.2. requires that

15. Drawings must comprise black lines and may be shaded where the shading assists in representing the shape of a thing provided that it does not obscure other elements of the drawing.


20A. Photographs must be black and white, clear and capable of direct reproduction.

Whilst rule 46(2)a EPC requires that:

"Drawings shall be executed without colourings in durable, black, sufficiently dense and dark, uniformly thick and well-defined lines and strokes".

According to the Guidelines for Examination,

"The EPC makes no express provision for photographs, they are nevertheless allowed where it is impossible to present in a drawing what is to be shown and provided that they are directly reproducible and fulfil the applicable requirements for drawings … Colour photographs can be submitted but will be scanned, printed and made available via file inspection only in black and white (Guidelines A-IX. 1.2).

This is less than ideal, as important detail can be lost in the conversion process.

For the PCT, rule 11.13(a) states:

"Drawings shall be executed in durable, black, sufficiently dense and dark, uniformly thick and well-defined, lines and strokes without colorings".

Like the EPC, the PCT makes no provision for photographs or drawings. Nevertheless, they may be submitted where it is impossible to present in a black and white drawing what is to be shown (PCT Applicants Guide 5.159).

WIPO has made some progress towards the use of colour drawings. Where receiving offices transmit an electronically filed application with colour drawings to the International Bureau (IB), the IB will make that copy available on PATENTSCOPE, if possible. However, the black and white version remains the official version. Moreover, for the purposes of the international application, all images will be converted to black and white.

GB, EP, and WO applications that include colour elements will be given a filing date, but a formal objection will be raised requiring correction of the drawings. EP applications (Art 90(5) and rule 57(i)EPC) and GB applications (s15A(7)) will be refused if the correction is not supplied in due time. Under the PCT, if the applicant does not provide black and white drawings following an invitation to correct, then the IB will simply convert them to black and white themselves for publication.

The US, on the other hand, does allow the filing of colour drawings in utility patents, where they are "necessary as the only practical medium by which to disclose the subject matter sought to be patented" (MPEP 608.02 V) The applicant must file a petition for the acceptance of colour drawings, pay a fee and include a text into the application informing the reader that the application includes colour drawings. The application is not, in fact, published in colour, but the colour version is provided by the Office upon request and payment of a fee.

So, in an age where data storage is cheap and colour illustration is ubiquitous, what is stopping all offices accepting colour drawings and publishing specifications in colour? Well, largely, it seems to have been due to the sheer volume of behind-the-scenes changes required to implement such a change, not only in rules governing the content of the specification but in automated IT systems. In the case of the PCT, these changes would not only require amendments to PCT regulations and national law, but also the overhaul of computer systems at the IB, receiving offices, and national offices.

There is cause for cautious optimism, however; broader change may be just around the corner. As noted above, WIPO recognises that "the ability to file and reliably process color drawings is one of the primary wishes of PCT users" and has been working for some time to address the issue(1). The IB is in the process of updating the IT systems for processing and publication with the intention (inter alia) of allowing the processing of applications having colour drawings. In the first instance, the IB is planning to offer to applicants who file International Applications with colour drawings in XML format the option of making these documents available as an unofficial additional view in the register. Changes to r11 PCT are required to place these changes on a formal footing, of course, but proposals for these changes are expected to be presented to the PCT Working Group in the near future.

In April 2021, the UK government launched a programme (The so-called "One IPO" programme) to transform the way IP services are delivered and to make the most of modern digital technology. A consultation carried out as part of this programme identified the importance of updating the types of media used as drawings, including the use of (inter alia) colour photographs. As a result, and in a similar manner to the EPO, legislative changes were proposed that give the IPO the flexibility to direct the format of patent applications. There will, however, be no changes to the types of media that are accepted in patent applications at this time. Hearteningly, though, the UKIPO "will engage with other patent offices and seek to build international understanding and acceptance of colour figures in patent applications" (2).

At the EPO, legal changes to support a digital transformation are afoot, too. In 2022, the Administrative Council agreed a new set of rules(3), as a result of which rule 46 was abolished and decisions on the form of a European application are now placed in the hands of the President. This is intended to provide flexibility to update these requirements as the digital transformation proceeds. A Decision of the President duly followed on 22nd November 2022(4). This decision simply reiterated the previous rules and came into force 1st February 2023, paving the way for further discussions with national offices, WIPO, and users.

We can only hope that these ambitious changes will provide the impetus for similar changes in national laws worldwide and that someday soon, we will all be able to file and prosecute applications in colour.

If you have any questions, please contact us at


(1) PCT/WG/17/12, 24th January 2024

(2) Government publishes transformation consultation response - GOV.UK (

(3) Decision of the Administrative Council CA/D 10/22 of 13.10.2022 (OJ EPO 2022, A101)

(4) Decision of the President of the European Patent Office dated 25th November 2022 on the presentation of application and other documents

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