数字全息再现像中，零级衍射的存在影响了再现像的成像质量。在对几种简单消零级方法利弊分析的基础上，提出了一种定域灰度值非线性变换法。该方法不需要其他光学元件和额外的操作，即可以增强全息干涉图像的条纹对比度，同时消除零级衍射和背景噪声。将其应用在全息干涉术测量物体微小位移的实验中，成功消除了零级衍射的干扰，获得了高对比度的干涉条纹，并实现了物体微小位移的高精度测量。

In digital holographic reconstruction, the zero-order diffraction impacts the quality of the real image. A new method that changes the gray value nonlinearly in an appointed gray range is put forward, which is based on analysis of the pros and cons of several other simple methods to eliminate the zero-order diffraction. This method not only enhances the contrast of holographic interference fringes, but also eliminates the zero-order and background noise. In addition, this method doesnt require other optical elements and additional operations. Experiments were performed in micro displacement measurement with holographic interferometry, and the interference of the zero-order diffraction was successfully eliminated, obtaining high contrast holographic interference fringe. High-precision measurement was achieved.