It is important to estimate the noise of digital image quantitatively and efficiently for many applications such as noise
removal, compression, feature extraction, pattern recognition, and also image quality assessment. For these applications,
it is necessary to estimate the noise accurately from a single image. Ce et al proposed a method to use a Bayesian MAP
for the estimation of noise. In this method, the noise level function (NLF) which is standard deviation of intensity of
image was estimated from the input image itself. Many NLFs were generated by using computer simulation to construct
a priori information for Bayesian MAP. This a priori information was effective for the accurate noise estimation but not
enough for practical applications since the a priori information didn't reflect the variable characteristics of the individual
camera depending on the exposure and shutter speed.
In this paper, therefore, we propose a new method to construct a priori information for specific camera in order to
improve accuracy of noise estimation. To construct a priori information of noise, the NLFs were measured and
calculated from the images captured under various conditions. We compared the accuracy of noise estimation between
proposed method and Ce's model. The results showed that our model improved the accuracy of noise estimation.
We are developing an ultra-lightweight and inexpensive mid-sized telescope on an alt-azimuth mount. Utilizing commercially available truss elements and compact high precision bearings we are able to achieve significant weight and cost savings while maintaining mechanical strength and stability. The design features a structure integrating the mirror-cell and the altitude bearing's arc-rails coupled to a short-armed fork through R-Guide bearings. The fork sits on a turn-table providing rotation about the azimuth axis. The telescope-tube connects to an extension of the mirror-cell. The mount can carry a mirror of up to 3m in diameter, yet is only 5m from the bottom of the base to the top ring and weights only 5000kg without the primary mirror. Assembly of the mount was performed by three students in two weeks and within the budget of $80,000. We measured the altitude bearing's motion accuracy to be 0".07 (rms) at a constant speed of 2".2/s for 15 minutes in both forward and backward motion without any sign of hysteresis, stick-slip, or backlash.