An instrument to measure the dimensions of skin wounds

A new instrument based on the principle of color-coded structured light has been developed to measure the area, volume, and color of skin ulcers and pressure sores. A set of parallel stripes of alternating colors is projected onto the ulcerated skin and recorded by a CCD camera. The color, width, distance, and coding of the stripes have been adjusted to maximize the precision of the instrument. Algorithms have been developed to extract the stripes and determine their centers to better than 0.1 mm, even under circumstances where the skin reflectivity varies widely over short distances. A depth map for the ulcerated skin is calculated by triangulation. The volume of the ulcer is that sandwiched between the base of the lesion and the original healthy skin, which is simulated by a cubic spline interpolation between the surrounding areas of healthy skin. The instrument measures the ulcer's volume with a precision of about 5% provided the ratio of the ulcer's volume to area is greater than 0.4 cm. The technique has been used in hospital clinics for a wide variety of wounds     

Periodic quasi-orthogonal spline bases and applications toleast-squares curve fitting of digital images

Presents a new covariant basis, dubbed the quasi-orthogonal Q-spline basis, for the space of n-degree periodic uniform splines with k knots. This basis is obtained analogously to the B-spline basis by scaling and periodically translating a single spline function of bounded support. The construction hinges on an important theorem involving the asymptotic behavior (in the dimension) of the inverse of banded Toeplitz matrices. The authors show that the Gram matrix for this basis is nearly diagonal, hence, the name "quasi-orthogonal". The new basis is applied to the problem of approximating closed digital curves in 2D images by least-squares fitting. Since the new spline basis is almost orthogonal, the least-squares solution can be approximated by decimating a convolution between a resolution-dependent kernel and the given data. The approximating curve is expressed as a linear combination of the new spline functions and new "control points". Another convolution maps these control points to the classical B-spline control points. A generalization of the result has relevance to the solution of regularized fitting problems.     

一种新的轮廓特征提取和检索算法

提出了一种新的轮廓图像检索算法.首先,根据内角大小将轮廓像素划分为凸角点、凹角点及平滑点3种类型,并分别提取其距离直方图;在此基础上,给出了两个新的轮廓空间特征描述符:相对佗置分布及相关单元熵,分别描述角点间及平滑点间的相互关系;最后,结合上述3种特征,给出了轮廓间的相似性度量准则.实验结果表明,该算法取得了比传统方法更好的检索效果.     

Comparison of interpolating methods for image resampling

When resampling an image to a new set of coordinates (for example, when rotating an image), there is often a noticeable loss in image quality. To preserve image quality, the interpolating function used for the resampling should be an ideal low-pass filter. To determine which limited extent convolving functions would provide the best interpolation, five functions were compared: A) nearest neighbor, B) linear, C) cubic B-spline, D) high-resolution cubic spline with edge enhancement (a = -1), and E) high-resolution cubic spline (a = -0.5). The functions which extend over four picture elements (C, D, E) were shown to have a better frequency response than those which extend over one (A) or two (B) pixels. The nearest neighbor function shifted the image up to one-half a pixel. Linear and cubic B-spline interpolation tended to smooth the image. The best response was obtained with the high-resolution cubic spline functions. The location of the resampled points with respect to the initial coordinate system has a dramatic effect on the response of the sampled interpolating function the data are exactly reproduced when the points are aligned, and the response has the most smoothing when the resampled points are equidistant from the original coordinate points. Thus, at the expense of some increase in computing time, image quality can be improved by resampled using the high-resolution cubic spline function as compared to the nearest neighbor, linear, or cubic B-spline functions.     

Q开关Nd:YAG激光治疗皮肤色素损害的临床应用和动物实验

目的观察并比较Q开关Nd:YAG1064nm和532nm波长激光照射治疗不同皮肤色素损害的临床疗效;并探讨Q开关激光去除皮肤色素细胞的机理。方法皮肤色素损害患者227例,其中太田痣142例、雀斑9例、文身(黑色)76例;针对不同病变类型,采用不同波长和工作参数进行激光褪色治疗;用2种不同的Q开关激光作用于豚鼠的有色皮肤区,观察其结果。结果经过1~9次临床治疗,不同皮肤色素损害的有效率分别为:太田痣82.1%、雀斑66.6%、文身96.0%。所有病例在治疗后均未遗留瘢痕;动物实验所见:Q开关激光治疗后皮肤色素即被气化或碎裂、色素病变消失,色素细胞呈空泡状,但色素细胞轮廓的框架仍可完整保留,色素细胞周围组织并未受损伤,仍可存活。结论应用Q开关Nd:YAG激光治疗皮肤色素损害文身的褪色效果最好,对太田痣、雀斑的褪色效果较好;Q开关激光只破坏色素颗粒或色素细胞,而邻近的正常细胞不被破坏,是目前治疗皮肤色素性疾病较有效副作用较小的方法。     

一种新的快速局部不变特征算法

针对传统局部不变特征算子主方向提取不准确和匹配阶段过于耗时的问题,提出一种基于RI-LBP 算子和混合spill 树的快速局部不变特征算法。首先提出一种FAST-Difference 算法,提取出模板图像和待匹配图像的稳定特征点,然后使用旋转不变的RI-LBP 描述符计算特征向量,最后对特征向量集使用混合spill 树进行匹配并使用RANSAC 算法剔除误匹配点。RI-LBP 算子自身的旋转不变性能够在一定程度上克服特征点主方向确定不准确的缺点,使特征描述符的提取更加稳定,并生成更简单的53 维局部不变特征描述符。混合spill 树相对于kd-tree 省略了回溯过程,对于高维数据拥有更好的匹配效率。实验证明:该算法与SURF 算法描述能力相近,旋转和光照条件下比SURF 性能更优,并且匹配速度更快。     

CO2激光结合Q开关激光治疗色素痣临床疗效综合评定

目的：观察CO2激光结合Q开关532nm激光治疗面部突出皮肤的色素痣的临床综合疗效。方法：先用CO2激光选择脉冲模式,烧灼皮损达到或略低于周围正常皮肤水平,继之用Q开关激光532nm波长治疗,治疗面部色素痣67例,271粒色素痣。结果：232粒色素痣痊愈,41粒色素痣有显效。Ⅰ、Ⅱ级（痊愈＋显效）率为98．54％。治疗次数平均为1．27次。结论：采用CO2激光结合Q开关激光治疗面部突出的色素痣疗效好,治愈率高,疗程短,无明显瘢痕形成。     

基于透视不变量的平面曲线的识别

提出一种快速有效的平面曲线的识别方法,在这种方法中,我们从单幅图象中提取表征曲线形状的描述子,该描述子由曲线上透视不变点之间的射影距离不变量构成,且不受物体和摄象机之间的位置、方向以及摄象机物理参数的影响。因此这种识别算法不受透视畸变的限制,本文用一组起初的平面物体进行了识别实验,结果表明这些形状描述 平面 曲线的识别有很好的性能。     

双脉冲激光对生物组织的热和声损伤机理研究

本文从提高治疗效果减小生物组织声损伤和提高激光的能量利用率考虑，提出双脉冲治疗皮肤色素性病损的方法，并建立皮肤组织的热传导模型，对多脉冲治疗时生物组织的热损伤和声损伤进行的理论分析，表明双脉冲治疗可以提高疗效，减小生物组织的声损伤。同时，为减小组织的热损伤，脉冲间隔最小应为4倍的组织热驰豫时间。经病理实验得到验证。实验中双脉冲激光为200微秒。     

Arranging and Interpolating Sparse Unorganized Feature Points With Geodesic Circular Arc

A novel method to reconstruct object boundaries with geodesic circular arc is proposed in this paper. Within this framework, an energy of circular arc spline is utilized to simultaneously arrange and interpolate each member in the set of sparse unorganized feature points from the desired boundaries. A general form for a family of parametric circular arc spline is firstly derived and followed by a novel method of arranging these feature points by minimizing an energy term depending on the circular arc spline configuration defined on these feature points. With regard to the fact that the energy function is usually nonconvex and nondifferentiable at its critical points, an improved scheme of particle swarm optimizer is given to find the minimum for the energy in this paper. With this improved scheme, each pair of neighboring feature points along the boundaries of the desired objects are picked out from the set of sparse unorganized feature points, and the corresponding directional chord tangent angles are computed simultaneously to finish interpolation. We show experimentally and comparatively that the proposed method can perform effectively to restrict leakage on weak boundaries and premature convergence on long concave boundaries. Besides, it has good noise robustness and can as well extract multiple and open boundaries.      

Monte Carlo simulation of light-tissue interaction: three-dimensional simulation for trans-illumination-based imaging of skin lesions

Three-dimensional, voxel-based, and wavelength-dependent skin lesion models are developed and simulated using Monte Carlo techniques. The optical geometry of the Nevoscope with trans-illumination is used in the simulations for characterizing the lesion thickness. Based on the correlation analysis between the lesion thickness and the diffuse reflectance, optical wavelengths are selected for multispectral imaging of skin lesions using the Nevoscope. Tissue optical properties reported by various researchers are compiled together to form a voxel library. Tissue models used in the simulations are developed using the voxel library which offers flexibility in updating the optical properties and adding new media types into the models independent of the Monte Carlo simulation code.     

二氧化碳激光在皮肤美容上的应用及临床观察

本文通过对皮肤良性肿瘤、病毒性皮肤病、色素障碍性皮肤病患者３２０人供５０３例皮损数的ＣＯ２激光治疗，从美容的角度探讨了治疗效果及技术要点。３２０个患者通过ＣＯ２激光治疗皮损痊愈４８９例，显效１２，有效２例；无效无例数，８例出现萎缩性疤痕，１例出现增生性疤痕。从而说明了只有掌握适用症及操作的技术要点，ＣＯ２激光是一种良好的皮肤病美容治疗手段。     

基于带参数的多结点样条表示的物体轮廓曲线匹配

针对三维碎片自动拼合中的碎片匹配问题,提出了一种新的轮廓曲线的表示和匹配方法.曲线的表示用带参数的多结点样条插值曲线拟合从碎片物体的轮廓线上提取的数据点,同时计算轮廓曲线上各个点的曲率、挠率和法矢.通过比较不同曲线特征段之间的全曲率,度量轮廓曲线之间的可匹配程度,利用法矢对相似度较高的轮廓曲线进行可匹配性验证,实现三维碎片的匹配.实验结果表明,该算法取得了较好的拟合和匹配效果,为基于轮廓线匹配的物体形状的拼接奠定了基础.     

基于虚拟仪器技术的点云数据反求

在点云反求中,采取分段样条插值法拟合曲线,是非常实用和有效的处理方法.应用插值法的目的是使样条函数为低次多项式,确保拟合的曲线光滑连接.设计中,选取了具有优良数学特征的三次样条插值法,利用虚拟仪器技术,编写算法,使曲线通过所有扫描点后快速生成并显示.这种技术及方法可广泛应用于曲线设计与反求之中.     

Inertial snake for contour detection in ultrasonography images

Snakes, or active contour models are used extensively for image segmentation in varied fields. However, some major challenges restrict their use in many fields. The authors propose a new inertial snake model, that introduces an inertial effect of the control points into the snake framework. The proposed inertial force along with the first- and second-order continuity forces controls the spline motion through the concavities and also against weak edge forces. This smart force field, added to the inertial energy framework, posses the ability to adaptively reduce its effect near the true edges, so that the energy minimising spline converges into the edges. A greedy snake has been used for computation of the energy minimising spline. The algorithm has been tested on phantoms and ultrasound images as well. It is shown in the results that the proposed algorithm classifies the object from the background class in most of the images perfectly. Ultrasound images of a lower limb artery of an adult woman have been tested with this algorithm, and also extended for motion tracking.