Introduction to Image Classification
Process of Classification
- Classification process starts with the identification of number of classes and classification scheme such as urban, agriculture, forest, river etc. in which all the pixel will be classified.
- In the next stage field conduction/knowledge as well as secondary data need to acquire for classification
- Satellite image pre-processing, it includes geometric correction and radiometric correction as well as atmospheric corrections can be performed as per requirement
- Delineation and extraction of the study area using image processing tool from satellite image for the classification
- Image can be enhanced using various enhancement tools from basic enhancement process such as brightness and contrast adjustment to advance tools for example, linear stretching and gamma stretching etc.
- For image classification in image processing, usually two methods are deployed Supervised and unsupervised
- Supervised method-it is performed using signature collection from satellite image and training sites generation for classification
- Unsupervised Method- Grouping of pixels based on repetitive iterations as well as incorporation of statistical and mathematical approach
- After classification of satellite image post processing performed to improve quality of classification, such as recoding, reclass, sieve and filtering etc.
- In the last accuracy assessed for classified satellite image using accuracy assessment tool, this process performed to assess the quality of satellite image to accept the classified images.