โ Scribed by Louis D. Silverstein
No coin nor oath required. For personal study only.
592 pp., $74.19 such matters, the ball was rolling. According to many developers, the CIE system was to be the solution.
The initial attempts to define colour reproduction in Colour Management is a topic of considerable interest in many industries at present, as the transfer of digital im-this way probably has its origins in graphic arts, in which electronic images were first defined and reproduced by ages is increasingly adopted. The term is usually used to describe the procedures employed for ensuring that simi-their colorimetric parameters approximately 50 years ago. Subsequently, considerable experimental work spanning lar colour reproduction is achieved when the same image is reproduced across a variety of media using a ''device-the intervening years was undertaken with the occasional launch of products using these principles. However, due independent colour space'' for encoding the image. The term device-independent is used to differentiate the en-to many issues associated with the use of colorimetry, and more particularly problems of computational speed, coding scheme from those in which the encoding is defined such that it can be output to a device without em-most successful products did not use this principle, but tended to encode images directly in the domain appro-ploying any colour transformation at the time of output. Device-dependent coding has been widely used in many priate for output so that the films or plates used for printing could be generated with the minimum of computation. industries in the past; the graphic arts industry, for example, typically encodes its images by defining the amount However, as computation has ceased to be such a significant problem, this issue has become less critical. When of ink needed to reproduce an image and the CAD industries by the RGB signals needed to drive a colour display.
that factor is combined with the development of digital However, clearly these may not be the most effective imaging in many other industries, it is clear why the encoding schemes when an image is to be reproduced on need for a satisfactory colour encoding scheme has been many media. It was for this reason that various developers articulated so frequently and why the CIE system was pushed for a ''device-independent'' coding to be develseen as the answer. For many people there seemed no oped that would provide a neutral encoding scheme.
alternative. Having said that, it seems that the term colour manage-So, how does Digital Color Management by Giorgianni ment can be used more loosely in future. In recent months, and Madden help us to understand all these issues? In we have seen influential people in digital imaging proposone sense very well. The authors state in their preface ing that a device-dependent RGB encoding specification, that colour encoding-the representation of colour in nuwhich will provide the ''correct'' colour when images merical form-is not well understood and that this is the are displayed directly on HDTV colour monitors, be used underlying reason why problems of colour management for encoding images to be used on the Internet. Many still exist. This is a conclusion with which I heartily conpeople seem to consider that this encoding has a role in cur and am pleased to see aired to such a substantial colour management. If so it will help to dispel the myth degree in this book. The authors also state that their objecthat device-independent encoding is fundamental to coltive in writing the book is to make all the essential inforour management, which can be no bad thing. All that is mation required for a solid understanding of the technolneeded for accurate colour reproduction across media is ogy of managing and representing colour in the digital to ensure that the transformations between the encoded domain available in one text. It is designed for scientists, data and that required for output can be unambiguously engineers, programmers, and others who want to further defined in terms of colour; so long as the encoding that understanding. It this objective that I feel has been scheme can achieve this it is immaterial whether the enless successful. coding scheme has a device-dependent origin.
The authors ask us to read the book straight through, Whether data is directly encoded in a device-indepeneven if we believe we are familiar with most of the backdent form, or some specification is provided with the ground material. This I did and found that in general I image as to how device-dependent data should be interfelt that I had a ''good read.'' I found it somewhat turgid preted, a reference definition is needed. The belief that in parts, but as textbooks go it was really very readable. the CIE system of colorimetry provided such a specifica-Unfortunately, at the end of it I felt rather disappointed. From my perspective, quite a lot was missing.
But first let me reflect on what I see as its strong points.
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