Satellite Image Processing | Pre-Processing | Enhancement | Feature Extraction

Satellite Image Processing | Pre-Processing | Enhancement | Feature Extraction: Satellite Image Processing is a significant field in research and development. This is comprised of the images of the earth's surface that are taken from the artificial satellites or (SAR and RAR) cameras mounted on the aircraft. All the useful information that is gathered for detecting and tracking ships, ocean wave forecasting, agricultural monitoring, the military system, assessment of damages after flood or earthquake is acquired through satellite images. If the quality of the satellite image is good, then enough vital information can be obtained but if the quality of the satellite image is bad, then there is a problem in obtaining useful information.

Satellite Image Processing

The transmitter of a camera mounted on aircraft or artificial satellites transmit high-frequency electromagnetic radiations (radar waves) on the earth's target surface to capture the large terrain of the earth. These transmitted radar waves consistently hit the target object on the earth's surface. These transmitted radio waves are reflected back after hitting the target and are received by the receiver of the camera mounted on aircraft or artificial satellites. The reflected radar waves contain a lot of target information. This information is processed by the sensor of the camera. It requires huge computation to process this information. After computing this target information (reflected radar waves), the satellite image is created in the digital form. The satellite images have a lot of brightness and darkness in the images. Any particular scene depicting high energy shows the bright part in the satellite image and the low energy depicts the dark part in the satellite image.

The satellite images are captured in the digital form. Mainly there are four types of resolutions associated with satellite imagery. They contain enormous useful information. Then they are processed to extract the useful information. This processing includes three different steps:
  1. Pre-Processing,
  2. Enhancement, and 
  3. Feature Extraction.
Pre-Processing: Initially the raw satellite image data contains distortion due to the properties of the imaging system and imaging conditions. This type of distortion is corrected in this step. The correction procedures mainly include radiometric correction, geometric correction, and geo-referencing.

Enhancement: The image enhancement on satellite images is performed to aid the visual appearance of it. There are some basic enhancement methods for this purpose like grey level stretching for contrast enhancement and spatial filtering for edge enhancement. When transmitted radar waves hit the target on the ground to capture images then this continuous coherent interaction causes constructive and destructive interference that results in a generation of noise known as speckle noise. This noise degrades the satellite image adversely. The speckle noise reduction can be done by any despeckling method.

Feature Extraction: Now the information is extracted by categorizing the pixel values of satellite image into two classification groups i.e. "supervised" or"unsupervised" algorithms. The prior classification algorithm extracts the spectral features. And the later classification algorithm performs the clustering based on these spectral features. The final outcome of this step are maps (images), data, and reports.

                For more image processing topics refer:
Satellite Image Processing | Pre-Processing | Enhancement | Feature Extraction Satellite Image Processing | Pre-Processing | Enhancement | Feature Extraction Reviewed by Dr. Prabhishek Singh on May 09, 2020 Rating: 5

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