We study a technique for improving visualization quality of noisy multispectral images. Contrast form visualization approach is considered, which guarantees a non-zero contrast in the output image when there is a difference between the spectra of the object and the background in the input image. The improvement is based on channel weighting according to estimation of the noise level. We show this approach to reduce noise in color visualization of real multispectral images. The low-noise visualizations are demonstrated to be more comprehensive to a human on examples from a publicly available dataset of Earth surface images. Noise variance estimation needed for weighting uses the method proposed earlier by the authors. The validation dataset consists of publicly available images of Earth surface.
The energy parameters of an HF laser operating by using a new method for oxidising gas production, which is based on
the principle of two-region mixing, are optimised. The total amount of the inert diluent (helium) supplied to the laser
was varied during experiments by varying its relative fraction only in the second mixing region. For an optimal relative
fraction of the diluent in the second mixing zone and for an optimal position of the optical axis of the cavity under a
constant pressure in the gas generator, the laser radiation power and the specific power output could be increased by 50%
and 60 %, respectively, compared to the laser operation regime realised in our previous experiments. In this case, the
inert diluent amount decreased by 35% and the length of the lasing length increased by 20 %.
The numerical end experimental study of the energy and temporal characteristics of the output radiation of the CW medium-scale chemical HF/DF-laser with mechanical modulation of the optical resonator quality by the mirror rotation with frequency up to 1 kHz is carried out. In experiment, a peak power of the laser radiation pulses has exceeded the radiation power in CW mode of the HF-laser operation not less than in four times. The average power in repetitively pulsed mode is lower than one in CW mode, but it grows with increase of the modulation frequency. Time of the complete recovery of a small signal gain of the active medium, which is about 6 - 7 &mgr;s, is determined. Two numerical models are developed, which describe the dynamics of the laser oscillation in a mode of the resonator quality modulation for both HF- and DF-laser, some features of their operation are analyzed using these models.