In this paper, an adaptive color transform for image compression is introduced. In each block of the image coefficients of the color transform are determined from the previously compressed neighboring blocks using weighted sums of the RGB pixel values, making the transform block-specific. There is no need to transmit or store the transform coefficients because they are estimated from previous blocks. The compression efficiency of the transform is demonstrated using the JPEG image coding scheme. In general, the suggested transformation results in better PSNR values for a given compression level.
The green up-conversion emissions corresponding to the (2)H(11/2)->(4)I(15/2) and (4)S(3/2)->(4)I(15/2) transitions of the Er(3+) doped borosilicate glass were recorded, using a 978-nm semiconductor laser diode as an excitation source. The fluorescence intensity ratio (FIR) of the green c emissions at about 524 and 550 nm was studied as a function of temperature over the temperature range of 296 to 723 K. The maximum sensitivity and the temperature resolution derived from the FIR of the green up-conversion emissions were approximately 0.0038 K(-1) and 0.2 K, respectively. It was demonstrated that the prototype optical temperature sensor based on the FIR technique from the green up-conversion emissions in the Er(3+) doped borosilicate glass plays a major role in temperature measurement. (C) 2011 Society of Photo-Optical Instrumentation Engineers (SPIE). DOI: 10.1117/1.3569695]