The Effects of Adding Heartwood Extractives from Acacia confusa on the Lightfastness Improvement of Refined Oriental Lacquer

In this study, a renewable polymeric material, refined oriental lacquer (ROL), used as a wood protective coating, and the Acacia confusa Merr. heartwood extractive, which was added as a natural photostabilizer for improving the lightfastness of ROL, were investigated. The best extract conditions for preparing heartwood extractives and the most suitable amount of addition (0, 1, 3, 5, and 10 phr) were investigated. The lightfastness index including brightness difference (ΔL *), yellowness difference (ΔYI), and color difference (ΔE *), and their applied properties of coating and film were measured. In the manufacture of heartwood extractives, the yield of extractives with acetone solvent was 9.2%, which was higher than that from toluene/ethanol solvent of 2.6%, and also had the most abundant total phenolic contents (535.2 mgGAE/g) and total flavonoid contents (252.3 μgRE/g). According to the SEM inspection and FTIR analysis, the plant gums migration to the surface of films and cracks occurred after UV exposure. The phenomena for photodegradation of ROL films were reduced after the addition of heartwood extractives. Among the different amounts of the heartwood extractives, the 10 phr addition was the best choice; however, the 1 phr heartwood extractive addition already showed noticeable lightfastness improvement. The drying times of ROL were extended and film performances worse with higher additions of heartwood extractives. Among the ROL films with different heartwood extractive additions, the ROL film with 1 phr addition had superior films properties, regarding adhesion and thermal stability, compared with the films of raw oriental lacquer.

Study on Local to Global Radiometric Balance for Remotely Sensed Imagery

Due to the difference of factors, such as lighting conditions, shooting environments, and time, there is compound brightness difference between adjacent images, which includes local brightness difference and radiometric difference. This paper proposed a method to eliminate the compound brightness difference of adjacent images after mosaicking, named local to global radiometric balance. It includes the brightness compensation model and brightness approach model. Firstly, the weighted average value of each row and column of image are calculated to express the brightness change; secondly, according to weighted average value, the brightness compensation model is built; thirdly, combined with the blocking method, the brightness compensation model is applied to image. Based on the value after above process, the brightness approach model is established to make the gray value of adjacent images approach to the mosaic line. In the paper, the standard deviation, MSE (mean square error) and mean value are used as the measure indices of the effect of brightness balance. The three groups of experimental results show that compared with the brightness stretch method, the histogram equalization method and the radiometric balance method, the local to global radiometric balance method not only realizes compound brightness balance, but also has better visual effects than others.

Effects of Adding Antioxidants on the Lightfastness Improvement of Refined Oriental Lacquer

Refined oriental lacquer (ROL) is a natural polymeric material with a satiny texture, elegant beauty, and high durability for wood furniture and handicraft finishing. However, its poor lightfastness, which results from the photo-degradation or photo-oxidation of its main component, catechol derivatives, must be improved for its widespread utilization. In this study, two experiments were performed. First, five types of antioxidants, including three primary antioxidants, such as 2,2′-methylenebis(6-nonyl-p-cresol) (coded as AO-1), 2,2′-methylenebis(6-tert-butyl-4-methylphenol) (AO-2), and bis [4-(2-phenyl-2-propyl) phenyl] amine (AO-N), and two secondary antioxidants, such as tris (2,4-ditert-butylphenyl) phosphite (AO-P) and dilauryl thiodipropionate (AO-S), were investigated to determine which is the most effective for improving the lightfastness of ROL. Secondly, the appropriate quantity of the best antioxidant, including 0, 1, 2, 3, 5, and 10 phr, was also determined. The lightfastness parameters, such as brightness difference (ΔL*), yellowness difference (ΔYI), and color difference (ΔE*), as well as other coating and film properties, were assessed. The results showed that the primary antioxidants had higher efficiency than secondary antioxidants for improving the lightfastness of ROL. Among the primary antioxidants, the 5 phr AO-N was the most effective at improving the lightfastness of ROL; however, 1 phr addition had already shown significantly improved efficiency. In addition, the drying time of ROL was extended and film properties decreased when increasing the content of AO-N, but the 1-phr-containing ROL displayed superior film properties, especially adhesion and bending resistance, compared with the raw ROL film.

Fast pupil tracking based on the study of a boundary-stepped image model and multidimensional optimization Hook-Jives method

A new fast method for pupil detection and eyetracking real time is being developed based on the study of a boundary-step model of a grayscale image by the Laplacian-Gaussian operator and finding a new proposed descriptor of accumulated differences (point identifier), which displays a measure of the equidistance of each point from the boundaries of some relative monotonous area (for example, the pupil of the eye). The operation of this descriptor is based on the assumption that the pupil in the frame is the most rounded monotonic region with a high brightness difference at the border, the pixels of the region should have an intensity less than a predetermined threshold (but the pupil may not be the darkest region in the image). Taking into account all of the above characteristics of the pupil, the descriptor allows achieving high detection accuracy of its center and size, in contrast to methods based on threshold image segmentation, based on the assumption of the pupil as the darkest area, morphological methods (recursive morphological erosion), correlation or methods that investigate only the boundary image model (Hough transform and its variations with two-dimensional and three-dimensional parameter spaces, the Starburst algorithm, Swirski, RANSAC, ElSe). The possibility of representing the pupil tracking problem as a multidimensional unconstrained optimization problem and its solution by the Hook-Jeeves non-gradient method, where the function expressing the descriptor is used as the objective function, is investigated. In this case, there is no need to calculate the descriptor for each point of the image (compiling a special accumulator function), which significantly speeds up the work of the method. The proposed descriptor and method were analyzed, and a software package was developed in Python 3 (visualization) and C ++ (tracking kernel) in the laboratory of the Physics and Mathematics Faculty of Kamchatka State University of Vitus Bering, which allows illustrating the work of the method and tracking the pupil in real time.

Dense Disparity Computing Method Based on Mesh Aggregation and Snake Optimization for Stereo Vision

In order to generate continuous and dense disparity images, a stereo matching method based on mesh aggregation and Snake optimization is proposed in this article. First, the reference pixels are obtained, so as to improve the suppression effect of the brightness difference in Census transform and improve the accuracy of initial matching cost calculation. Second, the image is divided by SLIC super pixel segmentation method, and the neighborhood pixels are searched according to the mesh search in the region, and the matching cost of these pixels are aggregated together according to the corresponding weight to complete cost aggregation of the pixels to be matched. Third, the Snake algorithm is used in optimizing the boundary of the disparity region. Eight classes of images on the Middlebury platform are selected as the test images, and the four algorithms on the Middlebury platform are selected as reference algorithms to carry out the experimental research. The experimental results show that proportion to bad pixels is low and disparity is continuous and dense on the disparity image calculated by the algorithm proposed in this article. Performance of the proposed method is close to LocalExp algorithm which is the best on the Middlebury platform, and the proposed method can be better applied in the stereo vision.

Application of generalized method of least modules in problems of processing and analysing images

The article describes the use of nonlinear smoothing filter for image processing and analysis. Description of the model of the smoothing filter based on the generalized method of the least absolute values is given. The filter constructed on the basis of the offered model efficiently reduces the noise on brightness difference. Along with noise reduction in the contrast images, this method can be used for the solving problems of machine vision, medical diagnostics, etc. It has been found that nonlinear filtration on the basis of the generalized method of the least modules allows to solve such problems as clarification of the boundaries of contrast objects and segmentation of the image. There has been shown the possibility of recovering the boundaries of the images in which the contrast borders were blurry. X-ray image of an animal hand with defocusing was used as an example. After filtering, the contrast boundary was restored to the place where it was originally located. When processing a fluorography image, the filter removed various artifacts from the image and increased the contrast. Removal of artifacts along with the recoveries of the boundaries of contrast objects improves the overall “readability” of the fluorography image and also allows seeing earlier not distinguishable details on the image. Examples of the filter application in the clustering problem using the k-means algorithm are given. Due to the lack of this algorithm, applying it directly to the image does not give an acceptable result. However, after processing the original image with a nonlinear filter, the application of the k-means algorithm yields the desired result.

Laser Spot Center Location Method for Chinese Spaceborne GF-7 Footprint Camera

The Gaofen-7 (GF-7) satellite is equipped with two area array sensor footprint cameras to capture the laser altimeter spot. In order to establish a direct correspondence between the laser data and the stereo image data, a new method is proposed to fit the center of the spot using the brightness difference between the spot image and the footprint image. First, the geometric registration between the spot image and the footprint image is completed based on feature matching or template matching. Then, the brightness values between the two images are extracted from the corresponding image position to form a measurement, and the least squares adjustment method is used to calculate the parameters of the brightness conversion model between the spot image and the footprint image. Finally, according to the registration relationship, the center of the identified spots is respectively positioned in the footprint images, so that the laser spots are accurately identified in the along-track stereo footprint images. The experimental results show that the spot error of this method is less than 0.7 pixel, which has higher reliability and stability, and can be used for a GF-7 satellite footprint camera.