Summary of the matched filter algorithm procedure.
The template dictionary
The matched filter template dictionary is a vital component to the success of the program. This dictionary contains a sample of each character, A-Z and 1-9. Each image is obtained from an actual license plate image, converted to black and white, and resized to 256x400 pixels to reduce processing time. Our library of individual character samples was the result of cropping the characters out of several different license plate templates. We finally stored the template dictionary as a cell in MATLAB so we could run the program immediately when we input a license plate image.
Matched filter algorithm
In order to identify characters on the license plate, we must run our test image through a series of steps (Figure 1).
1. image normalization
First, to match the template dictionary samples, every license plate is resized to the standard 256 by 400 pixels. Then, it is processed into a black and white image, with the pixel value 0 corresponding to black and pixel value 1 corresponding to white. This was done to set up for a 2D correlation between the two images.
2. image partition
We then partition the image into 7 different sections, one for each individual character of the license plate. This was done to make the computation more efficient, as we will only compute the correlation between our template dictionary, which contains our library of all of the license plate characters, and the sections of the license plate that contain each individual character.
3. rescale pixel values
Our next step is to shift the pixel values from [0,1] to [-0.5,0.5]. When we compute the correlation between the partitions of the license plate and the template characters, this will ensure we obtain only positive values if the images are the same, and negative values in that region if they are different.
4. two-dimensional correlation
To check for matches between our two images, we perform a correlation between the test license plate and the each entry in the template dictionary. To set this up, our program rescales the pixel values by calculating 1/2 - each pixel value. Now the pixels to range from 1/2 (black) to -1/2 (white).
Next we flip the template character upside down and right to left and run the Matlab 'conv2' function. This is equivalent to a 2D correlation between the two images. Two negative numbers (black and black) will return a positive result and two positive numbers (white and white) will return a positive result as well. Through this method, we can obtain all the matches between the two images.
Equation for 2d convolution
Equation for 2D Discrete Convolution.
Matched filter algorithm
Diagram of Matched Filter Algorithm for License Plate Recognition.
Program results
On each license plate, we section the entire image to obtain each character (110x40). After running a convolution between all the test image sections and the template dictionary, we find the highest correlation values to determine the right character. Our program will return the identified characters in a string, in order of their location on the license plate. This string should match the characters on the actual license plate.
Questions & Answers
A golfer on a fairway is 70 m away from the green, which sits below the level of the fairway by 20 m. If the golfer hits the ball at an angle of 40° with an initial speed of 20 m/s, how close to the green does she come?
A mouse of mass 200 g falls 100 m down a vertical mine shaft and lands at the bottom with a speed of 8.0 m/s. During its fall, how much work is done on the mouse by air resistance
Chemistry is a branch of science that deals with the study of matter,it composition,it structure and the changes it undergoes
Adjei
please, I'm a physics student and I need help in physics
Adjanou
chemistry could also be understood like the sexual attraction/repulsion of the male and female elements. the reaction varies depending on the energy differences of each given gender. + masculine -female.
Pedro
A ball is thrown straight up.it passes a 2.0m high window 7.50 m off the ground on it path up and takes 1.30 s to go past the window.what was the ball initial velocity
2. A sled plus passenger with total mass 50 kg is pulled 20 m across the snow (0.20) at constant velocity by a force directed 25° above the horizontal. Calculate (a) the work of the applied force, (b) the work of friction, and (c) the total work.
you have been hired as an espert witness in a court case involving an automobile accident. the accident involved car A of mass 1500kg which crashed into stationary car B of mass 1100kg. the driver of car A applied his brakes 15 m before he skidded and crashed into car B. after the collision, car A s
can someone explain to me, an ignorant high school student, why the trend of the graph doesn't follow the fact that the higher frequency a sound wave is, the more power it is, hence, making me think the phons output would follow this general trend?
Nevermind i just realied that the graph is the phons output for a person with normal hearing and not just the phons output of the sound waves power, I should read the entire thing next time
Joseph
Follow up question, does anyone know where I can find a graph that accuretly depicts the actual relative "power" output of sound over its frequency instead of just humans hearing
Joseph
"Generation of electrical energy from sound energy | IEEE Conference Publication | IEEE Xplore" ***ieeexplore.ieee.org/document/7150687?reload=true
A string is 3.00 m long with a mass of 5.00 g. The string is held taut with a tension of 500.00 N applied to the string. A pulse is sent down the string. How long does it take the pulse to travel the 3.00 m of the string?
