**3. Proposed methodology**

#### **3.1 Frequency and orientation angle selection for phase grating**

According to rule of phase grating, value of the grating frequency (0) should be high. Low grating frequency is creating aliasing problem and therefore it would be very difficult to reconstruct the original image. In this chapter, we propose to select

*Compression of High-Resolution Satellite Images Using Optical Image Processing DOI: http://dx.doi.org/10.5772/intechopen.94147*

0 = 1400, which is sufficient for filtering. In grating, value of the orientation angle (θ) varies from 0 to 3600

. We have worked with 0 deg orientation angle. The diffraction gratings used are illustrated in **Figures 1** and **2**.
