PURPOSE Wireless capsule endoscopy (WCE) has become an effective facility to detect digestive tract diseases. To further improve the accuracy and efficiency of computer-aided diagnosis system in the detection of intestine polyps, a novel algorithm is proposed for WCE polyp detection in this paper. METHODS First, by considering the rich color information of endoscopic images, a novel local color texture feature called histogram of local color difference (LCDH) is proposed for describing endoscopic images. A codebook acquisition method which is based upon positive samples is also proposed, generating more balanced visual words with the LCDH features. Furthermore, based on locality-constrained linear coding (LLC) algorithm, a normalized variance regular term is introduced as NVLLC algorithm, which considers the dispersion degree between k nearest visual words and features in the approximate coding phase. The final image representations are obtained from using the spatial matching pyramid model. Finally, the support vector machine is employed to classify the polyp images. RESULTS The WCE dataset including 500 polyp and 500 normal images is adopted for evaluating the proposed method. Experimental results indicate that the classification accuracy, sensitivity and specificity have reached 96.00%, 95.80% and 96.20%, which performances better than traditional ways. CONCLUSION A novel method for WCE polyp detection is developed using LCDH feature descriptor and NVLLC coding scheme, which achieves a promising performance and can be implemented in clinical-assisted diagnosis of intestinal diseases.

中文翻译：

---

WCE息肉检测基于新型特征描述符的归一化方差局部约束线性编码。

目的无线胶囊内窥镜检查（WCE）已成为检测消化道疾病的有效工具。为了进一步提高计算机辅助诊断系统在肠息肉检测中的准确性和效率，提出了一种新的WCE息肉检测算法。方法首先，通过考虑内窥镜图像丰富的色彩信息，提出了一种新颖的局部色彩纹理特征，称为局部色差直方图（LCDH），用于描述内窥镜图像。还提出了一种基于正样本的码本获取方法，可以产生具有LCDH特征的更加平衡的视觉单词。此外，基于局域约束线性编码（LLC）算法，引入了归一化方差正则项作为NVLLC算法，它考虑了k个最接近的视觉词与特征在近似编码阶段之间的分散程度。最终的图像表示是通过使用空间匹配金字塔模型获得的。最后，采用支持向量机对息肉图像进行分类。结果采用WCE数据集（包括500个息肉和500个正常图像）来评估该方法。实验结果表明，该方法的分类准确率，灵敏度和特异性分别达到96.00％，95.80％和96.20％，性能优于传统方法。结论利用LCDH特征描述符和NVLLC编码方案开发了一种新的WCE息肉检测方法，该方法具有良好的应用前景，可用于临床肠道疾病的诊断。