图像空间分辨率是图像质量评价的一项关键性指标,也是图像应用中举足轻重的一个参数。由于图像的成像方式不同,同一幅图不同方向的空间分辨率是变化的。由于影响图像空间分辨率的因素非常复杂,所以迄今为止尚无统一、有效的定量评价图像空间分辨率的理论和方法。该文基于熵理论和图像信息的特点,提出了变率信息熵的概念和算法,并进行了相关的特性分析。经过对模拟生成的条形码靶标图像和2004年印尼海啸地区的DMC等卫星遥感图像的处理和实验,验证了此方法可以客观、定量地评价一幅图像在水平和竖直方向的空间分辨率,实验结果证明了算法的有效性。

The spatial resolution is a measurement of the image details, and is also an indictor for the objects details, it appears the degree of the scene details. But up to now, there are no effective approaches to be quantifiable evaluating the image resolution. The manner of forming an image can be in two ways: scanning manner and non-scanning manner (for example: framing). In normal, forming an image by non-scanning manner has the same spatial resolution in the vertical and horizontal directions. But an image by scanning manner has the different spatial resolution in the two directions. The factors that influence the image spatial resolution exist: the contrast, shape, number of the scene which was observed and the lens, focus and instantaneous field of view(IFOV) of imaging system, the wavelength of radiation, aperture of imaging, model of image and the design of the imaging system, and so on. The main effective factors are distinguishing limit decided by the diffraction of the light,MTF(Modulate Transfer Function) of the imaging system,NSR(Noise Signal Ratio) and the design of imaging system. This paper is based on the entropy theory and the property of image information,bring forward the principle theory of varied information entropy, provided the conception, definition,method and character analysis. The experiment for bar images and remote sensing images of tsunami area approved that the method can be qualified to measure the spatial resolution in horizontal and vertical directions for the varied information equably, and provide a new method for the qualified measuring the image spatial resolution.