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Grayscale images are fundamental to many image processing applications like data compression, feature extraction, printing and tone mapping. However, some image information is lost when converting from color to grayscale. In this paper, we propose a light-weight and high-speed image decolorization method based on human perception of color temperatures. Chromatic aberration results from differential refraction of light depending on its wavelength. It causes some rays corresponding to cooler colors (like blue, green) to converge before the warmer colors (like red, orange). This phenomena creates a perception of warm colors "advancing" toward the eye, while the cool colors to be "receding" away. In this proposed color to gray conversion model, we implement a weighted blending function to combine red (perceived warm) and blue (perceived cool) channel. Our main contribution is threefold: First, we implement a high-speed color processing method using exact pixel by pixel processing, and we report a 5.7× speed up when compared to other new algorithms. Second, our optimal color conversion method produces luminance in images that are comparable to other state of the art methods which we quantified using the objective metrics (E-score and C2G-SSIM) and subjective user studies (decolorization and tone mapping). Third, we demonstrate that an effective luminance distribution can be achieved using our algorithm by using global and local tone mapping applications.

We present an ultra-low power 60-GHz band wakeup receiver (WuRx) designed and fabricated with a 0.18-m RF CMOS low-cost technology. The WuRx consists of an envelope detector, high-gain baseband amplifier, and clock and data recovery (CDR) circuit. Subthreshold-operated offset-voltage cancellers are used in the detector and baseband amplifier. The envelope detector can operate for an on-off keying (OOK) signal with a low bit-rate baseband and 60-GHz carrier, which is higher than the cutoff frequency (f T ) of 0.18-m MOSFETs. This is because the f T defines the maximum operating bit-rate of the baseband signal. The CDR circuit is composed of a clock recovery circuit using an injection-locked oscillator, short pulse generator, and D-type flip/flop. The fabricated WuRx successfully operates with power consumption of only 9 W from a 1.5-V supply and a high sensitivity of -68 dBm for a 350-kbit/s OOK signal with a 60-GHz carrier. The CMOS die area is 1.09 mm 2 . This is the first successful fabrication of a 60-GHz WuRx.

Abstract-We developed a wake-up receiver comprised of subthreshold CMOS circuits. The proposed receiver includes an envelope detector, a high-gain baseband amplifier, a clock and data recovery (CDR) circuit, and a wake-up signal recognition circuit. The drain nonlinearity in the subthreshold region effectively detects the baseband signal with a microwave carrier. The offset cancellation method with a biasing circuit operated by the subthreshold produces a high gain of more than 100 dB for the baseband amplifier. A pulse-width modulation (PWM) CDR drastically reduces the power consumption of the receiver. A 2.4-GHz detector, a high-gain amplifier and a PWM clock recovery circuit were designed and fabricated with 0.18-µm CMOS process with one poly and six metal layers. The fabricated detector and high-gain amplifier achieved a sensitivity of −47.2 dBm while consuming only 6.8 µW from a 1.5 V supply. The fabricated clock recovery circuit operated successfully up to 500 kbps.