Ocr eel709 ppt
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Transcript of Ocr eel709 ppt
Optical Character Recognition on Vehicle Number Plate
Avinash Singh Bagri
2009MT50541
EEL 709Dr Sumeet Agarwal
OverviewTakes image of the car and searches for the number plate in the image.
Once the probable number plate area is located it is given to OCR.
If OCR doesn’t recognize the characters from the image number plate areais searched again from the image.
If characters are recognized then number plate search is terminated.
Steps InvolvedImage division into small imagesdetecting probable number plate area
Recognizing number plate area
Parsing number plate to extract characters
Apply OCR to the parsed characters
Example
Original Image
Binarised image
Inverted binarised image
Extracting Number Plate
One piece of image that will be tested for number plate
Recognizing PlateSearch number plate in the broken pieces of vehicle image
Apply peak to valley to the candidate image pieces to further break the image pieceinto possible character
Image piece with maximum peaks in candidate character is selected as the numberplate
Column signature of the number plate image Column signature of the another image piece
Parsing plate
Images of all characters
Recognition of CharactersMethod of recognition of characters from an image containing these characters is based on object recognition techniques used in Digital Image Processing.
Two commonly used techniquesTemplate Matching using Correlation
Distance Measurement
Template MatchingTemplate matching using correlation
Based on performing correlation between segmented image
A character is required to be recognized and character template image which is used for recognition
CorrelationModified form of convolution
f(x,y): gray scale value at a specific element (x,y) in an image
f(x,y): image
g(x,y) character template
h(x,y) image after correlation.
Result of CorrelationBasic form of convolution
Result is an image, convolution of two matrices
The size of result matrix will be increased from input image matrices
Due to which we have to apply some thresh holding on resultant image
Normally value of thresh hold is little less than maximum value of resultant image.
LimitationsNoise free image with uniform illumination required
Numbers must be displayed in one line on the number plate
Problem associated with template image is proper acquisition of templateimage is required
Referenceshttp://www.sersc.org/journals/IJUNESST/vol6 no1/2.pdf
http://www.ele.uri.edu/~hansenj/projects/ele585/OCR/OCR.pdf
http://perun.pmf.uns.ac.rs/radovanovic/dmsem/completed/2006/OCR.pdf
http://www.nicomsoft.com/optical-character-recognition-ocr-how-it-works/
http://www.ancient-asia-journal.com/article/view/aa.06113/25
License Plate Number Recognition - New Heuristics and a Comparative Study of Classifiers (2F79e4150656ca79aeb9.pdf)
Kwaśnicka H. and WawrzyniakLicense B.; Plate Localization and Recognition in Camera Pictures
Thank you