Range gated underwater laser imaging technique can eliminate backscattering noise effectively. While the images
associated with underwater imaging systems are normally degraded seriously by the intervening water medium. And the
speckle noise is especially severe for the reason that we adopt the system based on intensified gate imaging technology.
Well known causes of image degradation underwater include turbidity, particulate matters in the water column, and the
interaction between light and medium as light travels through water. Consequently, using full image formation models to
design restoration algorithms is more complex in water than in air because it's hard to get the values of the model
parameters relating to water properties, e.g., attenuation and scattering coefficients. To improve the quality of the low
signal-to-noise ratio images obtained through range gated laser imaging system, an enhancement algorithm is proposed.
The main purpose of the algorithm proposed for processing underwater images is to filter out unwanted noises and
remain desired signals. This algorithm is based on the principle of the least square error method, which fits discrete
image data to continuous piecewise curves. To simply the fitting of image data, the interval of each row and column is
subdivided into several subintervals. Then a curve is used to fit the image data within the subinterval. To merge two
adjacent lines together, a weighting technique with a linear weighting factor is imposed. A series of experiments are
carried out to study the effects of the algorithm. And the signal-to-noise ratio shows that the proposed algorithm can
achieve high quality enhancement images.
All objects emit radiation in amounts related to their temperature and their ability to emit radiation. The infrared image
shows the invisible infrared radiation emitted directly. Because of the advantages, the technology of infrared imaging is
applied to many kinds of fields. But compared with visible image, the disadvantages of infrared image are obvious. The
characteristics of low luminance, low contrast and the inconspicuous difference target and background are the main
disadvantages of infrared image. The aim of infrared image enhancement is to improve the interpretability or perception
of information in infrared image for human viewers, or to provide 'better' input for other automated image processing
techniques.
Most of the adaptive algorithm for image enhancement is mainly based on the gray-scale distribution of infrared image,
and is not associated with the actual image scene of the features. So the pertinence of infrared image enhancement is not
strong, and the infrared image is not conducive to the application of infrared surveillance. In this paper we have
developed a scene feature-based algorithm to enhance the contrast of infrared image adaptively. At first, after analyzing
the scene feature of different infrared image, we have chosen the feasible parameters to describe the infrared image. In
the second place, we have constructed the new histogram distributing base on the chosen parameters by using Gaussian
function. In the last place, the infrared image is enhanced by constructing a new form of histogram. Experimental results
show that the algorithm has better performance than other methods mentioned in this paper for infrared scene images.
Scene Classification refers to as assigning a physical scene into one of a set of predefined categories. Utilizing the
method texture feature is good for providing the approach to classify scenes. Texture can be considered to be repeating
patterns of local variation of pixel intensities. And texture analysis is important in many applications of computer image
analysis for classification or segmentation of images based on local spatial variations of intensity. Texture describes the
structural information of images, so it provides another data to classify comparing to the spectrum. Now, infrared thermal
imagers are used in different kinds of fields. Since infrared images of the objects reflect their own thermal radiation,
there are some shortcomings of infrared images: the poor contrast between the objectives and background, the effects of
blurs edges, much noise and so on. Because of these shortcomings, it is difficult to extract to the texture feature of
infrared images.
In this paper we have developed an infrared image texture feature-based algorithm to classify scenes of infrared images.
This paper researches texture extraction using Gabor wavelet transform. The transformation of Gabor has excellent
capability in analysis the frequency and direction of the partial district. Gabor wavelets is chosen for its biological
relevance and technical properties In the first place, after introducing the Gabor wavelet transform and the texture
analysis methods, the infrared images are extracted texture feature by Gabor wavelet transform. It is utilized the
multi-scale property of Gabor filter. In the second place, we take multi-dimensional means and standard deviation with
different scales and directions as texture parameters. The last stage is classification of scene texture parameters with least
squares support vector machine (LS-SVM) algorithm. SVM is based on the principle of structural risk minimization
(SRM). Compared with SVM, LS-SVM has overcome the shortcoming of higher computational burden by solving linear
equations, and has been widely used in classification and nonlinear function estimation. Some experimental results are
given in the end. The result shows that Gabor wavelet transform is successful to extract the texture feature of infrared
image. Compared with other methods the method mentioned in this paper reduces the probability of recognition and
enhances the robustness.
Infrared images often display in gray scale. The low contrast and the unclear visual effect are the most notable characters
of infrared images that make difficult to observe. It is a fact that gray scale is not sensitive to human eyes, and it has only
60 to 90 just noticeable differences (JNDs). In comparison with gray scale, color scale might give up to 500 JNDs.
Usually people can distinguish many kinds of colors much more than grays. And in gray images, human don't have the
ability to tell apart the nuances about detail. Pseudo-color coding enhancement is the task of applying certain alterations
to an input gray-image such as to obtain color-image that is a more visually pleasing. In this paper, we introduced a
pseudo-color coding method based on human vision system for infrared images display. The HSI space is especially fit
for human vision system and is viewed as an approximation of perceptual color space. So the pseudo-color coding
method introduced is based on HSI space. In the first place, the individual functional relationship of Hue, Intensity, and
Saturation with gray scale level is established. In the second place, the corresponding RGB values are obtained through
transformation from the HSI color space to the RGB space. Lastly, the effect of Infrared images enhancement based on
the pseudo-color coding method is displayed. Results indicate that this method is superior to other methods through the
comparison.
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