云是一种自然现象，广泛、高频、不规律地出现在地球上空，因此云也经常在卫星影像上有所体现。在遥感影像中，云覆盖在很大程度上降低了数据的质量和利用率。云检测是进行遥感数据处理与分析的基础和必要环节，因此准确地提取云区所在位置是一个非常有意义的研究课题。提出基于HSV色彩空间的MODIS云检测算法，首次将HSV色彩空间引入云检测领域，提出的算法以云与其他地物的自身光谱特性和光谱差异为理论基础，以色彩空间HSV正变换为数学基础，将MODIS波段1、6和26的假彩色合成影像进行HSV正变换，对获得的色调值（H）进行简单的、客观的阈值限定，获得最后的云检测效果。该算法具有精度高、简单可行、客观性强和计算速度快等特点，适用于不同的下垫面和季节，云检测效果理想。

The cloud is a natural phenomenon.It widely， frequently， irregularly appears in the earth sky and thus in the satellite imagery.The cloud in the remote sensing images largely reduces remote sensing image quality and usage ratio.The presence of clouds in satellite images is a significant obstacle to land surface studies.Clouds in satellite images must be precisely identified prior to any further analysis in any case.Cloud detection is a necessary step in the image data analysis processing.Therefore accurately extracting the location of the cloud area becomes a very meaningful research subject.This paper has proposed a cloud detection algorithm for MODIS image based on HSV color space.The HSV color space is first introduced in cloud detection study.Based on the different objects spectrum， MODIS instrument channel characteristic and the HSV positive transformable formula， the algorithm firstly has processed the HSV positive transformation for the pseudo-color image composed of the band 1， band 6 and band 26.Then to carry a threshold for the hue， we can get the final cloud detected results.The algorithm is simple， impersonal and fast.The results show that the algorithm is applicable to all the different scenes and seasons and has basically completed.