Colour Recovery Working Group

Welcome to the Colour Recovery Working Group wiki.


This is an informal working group devoted to the advancement of technology for the recovery of PAL colour information embedded within B&W film telerecordings. The aim of the group is to produce software / systems which could be used by the BBC (or other broadcasters for that matter) in order to recover colour information from their archive film recording collections.


Membership of the group, and of this protected wiki, can be obtained by contacting James Insell.
Members agree not to exploit any IPR which may be formed in the progress of the work, and agree that all work can be made publicly accessible - through this wiki, or by other means.


This philanthropic, not-for-profit, Working Group does not have an affiliation with the BBC, and it survives through the generous donation of time and effort from its members.

Use of any source code, mechanism, device or principle described within this wiki, or published elsewhere by the group, is subject to the terms of the associated licence attributed. No warranty is offered and commercial exploitation is prohibited - save for that expressly granted by the group.

Any image or video contained within this wiki is copyright of the original owner and no attempt is made here to supersede copyright.

Background Information

During the late 1960’s and early 1970’s, many B&W film telerecordings were constructed from PAL colour source material. Often these were filmed without the prior removal of the PAL chroma signal. A fine pattern of dots appears across areas of the resultant B&W film where objects portrayed had a coloured appearance originally.

In the past, ‘chroma dots’ have been regarded as a nuisance – since the observer sees a pattern of fine detail where no fine detail was originally present. The scanning and display of the films with the use of PAL equipment also gives rise to problems. A spurious chroma signal is regenerated and this can be misinterpreted by PAL equipment as a real chroma signal. Distracting flashing coloured patterns can result upon display. Telecine operators ensure that the chroma dots are filtered out when scanning this type of film recording.

It is the premise of this Working Group that, rather than being regarded as a nuisance, the chroma dots embedded within this type of film recording could be usefully employed in the reconstruction of missing colour information. This information could be used to either directly recolour the B&W material, or to assist a separate process of colorisation.


Group News

The Colour Recovery Working Group is launched and a call for membership is made.
Founder members are welcomed to the Working Group.
The Working Group Wiki is launched.

-- James Insell 06/03/2007