二级灰度特征
second order gray characteristic
二维灰度级直方图
two-dimensional gray-level histogram
two-dimensional gray level histogram
灰度级别压缩
compression of grey levels
灰度级－彩色变换法
gray-color transform technique
灰度级等距离拉伸
gray-level in equal distance
灰度级水印
gray-scale watermark
grey-level watermarking
Gray level digital image watermarking
灰度级图像水印
Gray-level Image Watermarking