Why gabor filters

For example, if your target image is made up of edges in the diagonal direction, a Gabor filter set will give you a strong response only if its direction matches with the direction of the edges. Once it solidifies and you take a look at the solidified form, it looks like the surface of the structure. Gabor filter does something similar for images! Gabor Filters have received considerable attention because they closely resemble the human visual system.

All these attempts to design good filters are aimed at mimicking the human visual cortex. Humans have an uncanny ability to process visual data and distinguish things with extreme ease. Machines, not so much! The characteristics of certain cells in the visual cortex of some mammals can be approximated by these Gabor filters. In addition, these filters have been shown to possess optimal localization properties in both spatial and frequency domain. It will mould itself to suit different scenarios, like smoothness, orientation, scale, etc, of these edges.

This is the reason they are well suited for edge detection and texture segmentation problems. You are commenting using your WordPress. You are commenting using your Google account. You are commenting using your Twitter account.

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Why do we need this filter? What is a Gabor filter? Why is this so important? Where are they used in real life? Gabor filters have been used in many applications, such as: Texture segmentation: Gabor filters are used to separate multiple textures in an image. Then you can construct your Gabor filter or filter bank e.

The filter shape and orientation in the frequency domain can be controlled with the parameters of the operator.

The GaborSize determines the size in a frequency band, the Frequency determines the frequency, the Bandwidth tunes the frequency range, and the Orientation is the angle which controls the angular orientation of the filter in the frequency domain.

Images show filters constructed in the frequency domain. If the GaborSize is adjusted from the default value 1. Using e. The manifold applications of customized filter banks can also be found in literature. The filter can then be applied on the frequency image and afterwards the resulting filtered image can be converted back into the image domain:.

Demonstration of an example application of a somewhat arbitrary constructed Gabor filter bank: Extract upper left and lower left edge of a cell of a rotating grid automatically.

From left to right: the original grid, a generically constructed example filter bank rotated automatically , the convolution with the frequency image and the extracted borders. The extracted borders have been scaled for visibility reasons. And if you can read french, here is pdf on the creation of filter banks by Adrien Marion. A Gabor filter is some parametrization of the idea of edges.

This combines two somewhat contradictory ideas: an abrupt transition AND some fuzzy idea of where it is localized. It is mathematically a clever idea as it translates well in the Fourier domain: the Fourier transform of a Gabor is a Gaussian in Fourier space, and a Gaussian blob is the most neutral guess of something blurry you can make think of throwing darts and looking at the patterns of hits. As a consequence, when you use a Gabor, there is no 'right' formula: it all depends on what visual feature you want to detect.

In visual neuroscience, a popular choice is to chose a Gabor that corresponds in Fourier space to a blob on the logarithm of frequencies as from the Weber law, we are sensitive to relative differences of frequencies. These are log-Gabor filters. To understand Gabor filters, check first what filter parameterization would be best for your particular application. It is an edge detector.

It just applies the Gabor Transform. The Gabor filter is basically a Gaussian with variances sx and sy along x and y-axes respectively modulated by a complex sinusoid with centre frequencies U and V along x and y-axes respectively. See an example here. Sign up to join this community. The best answers are voted up and rise to the top. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams?

Learn more. What is the Gabor filter? And what are its main uses?