A real-time color space converter for the measurement of appearance

Abstract

The value of being able to specify and control color representations in perceptual terms is increasingly being recognized. The advantages of using perceptual color spaces include intuitive addressability, uniformity, independent control of lightness and chromatic contrast, and device characterization in perceptual terms. This paper presents the design and VLSI implementation of a new digital hardware structure which performs the conversion, in real-time, of the R, G and B color co-ordinates to the CIE L ∗u ∗v ∗ perceptually uniform color space. For a typical 512×512 pixel digital color image the number of required operations is 28×512 2 (including power and division operations) and these cannot be executed in software fast enough to cope with time critical applications. The high speed of operation is achieved by pipelining the data in a vector fashion. The structure is implemented using a DLM, 0.7 μm, N-well, CMOS process provided by the European Silicon Structures (ES2), and it occupies a silicon area of 6.40 mm×6.60 mm=42.24 mm 2. Its maximum speed of operation is 20 MHz and its throughput rate of operations is 260 MIPS. Targeted applications include display device modeling, device independent color reproduction, colorimetry instrumentation, virtual reality, and color machine vision applications.