1 | initial version |

**1-**It is possible to determine the frequency and the zebra orientation using **FFT transform**. Considering this characteristics, an image is divided in blocks of small size (e.g., 32x32).
**2-**The most simple and very common method used for zebra orientation extraction is based on **gradient computation**. Initially, the horizontal and vertical gradient are computed at each pixel using for example the sobel operator, then the image are divided in small blocks of size WxW (e.g., size 32x32) and computed the angle by analyzing the block.You can average the zebra orientation by **this method**.
**3-**The other method for zebra orientation extraction is based on **eigen values & eigen vectors** .It is given by the eigenvector having the highest eigenvalue.

2 | No.2 Revision |

**1-**It is possible to determine the frequency and the zebra orientation using **FFT transform**. Considering this characteristics, an image is divided in blocks of small size (e.g., ~~32x32).
~~32x32).

**2-**The most simple and very common method used for zebra orientation extraction is based on **gradient computation**. Initially, the horizontal and vertical gradient are computed at each pixel using for example the sobel operator, then the image are divided in small blocks of size WxW (e.g., size 32x32) and computed the angle by analyzing the block.You can average the zebra orientation by **this method**~~.
~~.

**3-**The other method for zebra orientation extraction is based on **eigen values & eigen vectors** .It is given by the eigenvector having the highest eigenvalue.

3 | No.3 Revision |

There are 3 common methods for compute of zebra orientation in blockwise mode.

**1-**It is possible to determine the frequency and the zebra orientation using **FFT transform**. Considering this characteristics, an image is divided in blocks of small size (e.g., 32x32).

**2-**The most simple and very common method used for zebra orientation extraction is based on **gradient computation**. Initially, the horizontal and vertical gradient are computed at each pixel using for example the sobel operator, then the image are divided in small blocks of size WxW (e.g., size 32x32) and computed the angle by analyzing the block.You can average the zebra orientation by **this method**.

**3-**The other method for zebra orientation extraction is based on **eigen values & eigen vectors** .It is given by the eigenvector having the highest eigenvalue.

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