DetectChars.py

# DetectChars.py

import cv2
import numpy as np
import math
import random

import Main
import Preprocess
import PossibleChar

# module level variables ##########################################################################

kNearest = cv2.ml.KNearest_create()

        # constants for checkIfPossibleChar, this checks one possible char only (does not compare to another char)
MIN_PIXEL_WIDTH = 2
MIN_PIXEL_HEIGHT = 8

MIN_ASPECT_RATIO = 0.25
MAX_ASPECT_RATIO = 1.0

MIN_PIXEL_AREA = 80

        # constants for comparing two chars
MIN_DIAG_SIZE_MULTIPLE_AWAY = 0.3
MAX_DIAG_SIZE_MULTIPLE_AWAY = 5.0

MAX_CHANGE_IN_AREA = 0.5

MAX_CHANGE_IN_WIDTH = 0.8
MAX_CHANGE_IN_HEIGHT = 0.2

MAX_ANGLE_BETWEEN_CHARS = 12.0

        # other constants
MIN_NUMBER_OF_MATCHING_CHARS = 3

RESIZED_CHAR_IMAGE_WIDTH = 20
RESIZED_CHAR_IMAGE_HEIGHT = 30

MIN_CONTOUR_AREA = 100

###################################################################################################
def loadKNNDataAndTrainKNN():
    allContoursWithData = []                # declare empty lists,
    validContoursWithData = []              # we will fill these shortly

    try:
        npaClassifications = np.loadtxt("classifications.txt", np.float32)                  # read in training classifications
    except:
        print "error, unable to open classifications.txt, exiting program\n"
        os.system("pause")
        return False
    # end try

    try:
        npaFlattenedImages = np.loadtxt("flattened_images.txt", np.float32)                 # read in training images
    except:
        print "error, unable to open flattened_images.txt, exiting program\n"
        os.system("pause")
        return False
    # end try

    npaClassifications = npaClassifications.reshape((npaClassifications.size, 1))       # reshape numpy array to 1d, necessary to pass to call to train

    kNearest.setDefaultK(1)

    kNearest.train(npaFlattenedImages, cv2.ml.ROW_SAMPLE, npaClassifications)

    return True
# end function

###################################################################################################
def detectCharsInPlates(listOfPossiblePlates):
    intPlateCounter = 0

    imgContours = None

    contours = []

    if len(listOfPossiblePlates) == 0:
        return listOfPossiblePlates
    # end if

            # at this point we can be sure the list of possible plates has at least one plate

    for possiblePlate in listOfPossiblePlates:
        possiblePlate.imgGrayscale, possiblePlate.imgThresh = Preprocess.preprocess(possiblePlate.imgPlate)

        if Main.showSteps == True:
            cv2.imshow("5a", possiblePlate.imgPlate)
            cv2.imshow("5b", possiblePlate.imgGrayscale)
            cv2.imshow("5c", possiblePlate.imgThresh)
        # end if

                # increase size of plate image for easier viewing and char detection
        possiblePlate.imgThresh = cv2.resize(possiblePlate.imgThresh, (0, 0), fx = 1.6, fy = 1.6)

                # threshold image to only black or white (eliminate grayscale)
        thresholdValue, possiblePlate.imgThresh = cv2.threshold(possiblePlate.imgThresh, 0.0, 255.0, cv2.THRESH_BINARY | cv2.THRESH_OTSU)

        if Main.showSteps == True:
            cv2.imshow("5d", possiblePlate.imgThresh)
        # end if

        listOfPossibleCharsInPlate = findPossibleCharsInPlate(possiblePlate.imgGrayscale, possiblePlate.imgThresh)

        if Main.showSteps == True:
            height, width, numChannels = possiblePlate.imgPlate.shape
            imgContours = np.zeros((height, width, 3), np.uint8)
            del contours[:]                                         # clear the contours list

            for possibleChar in listOfPossibleCharsInPlate:
                contours.append(possibleChar.contour)
            # end for

            cv2.drawContours(imgContours, contours, -1, Main.SCALAR_WHITE)

            cv2.imshow("6", imgContours)
        # end if

        listOfListsOfMatchingCharsInPlate = findListOfListsOfMatchingChars(listOfPossibleCharsInPlate)

        if Main.showSteps == True:
            imgContours = np.zeros((height, width, 3), np.uint8)
            del contours[:]

            for listOfMatchingChars in listOfListsOfMatchingCharsInPlate:
                intRandomBlue = random.randint(0, 255)
                intRandomGreen = random.randint(0, 255)
                intRandomRed = random.randint(0, 255)

                for matchingChar in listOfMatchingChars:
                    contours.append(matchingChar.contour)
                # end for
                cv2.drawContours(imgContours, contours, -1, (intRandomBlue, intRandomGreen, intRandomRed))
            # end for
            cv2.imshow("7", imgContours)
        # end if

        if (len(listOfListsOfMatchingCharsInPlate) == 0):			# if no groups of matching chars were found in the plate

            if Main.showSteps == True:
                print "chars found in plate number " + str(intPlateCounter) + " = (none), click on any image and press a key to continue . . ."
                intPlateCounter = intPlateCounter + 1
                cv2.destroyWindow("8")
                cv2.destroyWindow("9")
                cv2.destroyWindow("10")
                cv2.waitKey(0)
            # end if

            possiblePlate.strChars = ""
            continue						# go back to top of for loop
        # end if

        for listOfMatchingChars in listOfListsOfMatchingCharsInPlate:                           # within each list of matching chars
            listOfMatchingChars.sort(key = lambda matchingChar: matchingChar.intCenterX)        # sort chars from left to right
            listOfMatchingChars = removeInnerOverlappingChars(listOfMatchingChars)              # and remove inner overlapping chars
        # end for

        if Main.showSteps == True:
            imgContours = np.zeros((height, width, 3), np.uint8)

            for listOfMatchingChars in listOfListsOfMatchingCharsInPlate:
                intRandomBlue = random.randint(0, 255)
                intRandomGreen = random.randint(0, 255)
                intRandomRed = random.randint(0, 255)

                del contours[:]

                for matchingChar in listOfMatchingChars:
                    contours.append(matchingChar.contour)
                # end for

                cv2.drawContours(imgContours, contours, -1, (intRandomBlue, intRandomGreen, intRandomRed))
            # end for
            cv2.imshow("8", imgContours)
        # end if

                # within each possible plate, suppose the longest list of potential matching chars is the actual list of chars
        intLenOfLongestListOfChars = 0
        intIndexOfLongestListOfChars = 0

                # loop through all the vectors of matching chars, get the index of the one with the most chars
        for i in range(0, len(listOfListsOfMatchingCharsInPlate)):
            if len(listOfListsOfMatchingCharsInPlate[i]) > intLenOfLongestListOfChars:
                intLenOfLongestListOfChars = len(listOfListsOfMatchingCharsInPlate[i])
                intIndexOfLongestListOfChars = i
            # end if
        # end for

        longestListOfMatchingCharsInPlate = listOfListsOfMatchingCharsInPlate[intIndexOfLongestListOfChars]

        if Main.showSteps == True:
            imgContours = np.zeros((height, width, 3), np.uint8)
            del contours[:]

            for matchingChar in longestListOfMatchingCharsInPlate:
                contours.append(matchingChar.contour)
            # end for

            cv2.drawContours(imgContours, contours, -1, Main.SCALAR_WHITE)

            cv2.imshow("9", imgContours)
        # end if

        possiblePlate.strChars = recognizeCharsInPlate(possiblePlate.imgThresh, longestListOfMatchingCharsInPlate)

        if Main.showSteps == True:
            print "chars found in plate number " + str(intPlateCounter) + " = " + possiblePlate.strChars + ", click on any image and press a key to continue . . ."
            intPlateCounter = intPlateCounter + 1
            cv2.waitKey(0)
        # end if

    # end of big for loop that takes up most of the function

    if Main.showSteps == True:
        print "\nchar detection complete, click on any image and press a key to continue . . .\n"
        cv2.waitKey(0)
    # end if

    return listOfPossiblePlates
# end function

###################################################################################################
def findPossibleCharsInPlate(imgGrayscale, imgThresh):
    listOfPossibleChars = []                        # this will be the return value

    contours = []

    imgThreshCopy = imgThresh.copy()

    imgContours, contours, npaHierarchy = cv2.findContours(imgThreshCopy, cv2.RETR_LIST, cv2.CHAIN_APPROX_SIMPLE)

    for contour in contours:
        possibleChar = PossibleChar.PossibleChar(contour)

        if checkIfPossibleChar(possibleChar):
            listOfPossibleChars.append(possibleChar)
        # end if
    # end if

    return listOfPossibleChars
# end function

###################################################################################################
def checkIfPossibleChar(possibleChar):
    if (possibleChar.intBoundingRectArea > MIN_PIXEL_AREA and
        possibleChar.intBoundingRectWidth > MIN_PIXEL_WIDTH and possibleChar.intBoundingRectHeight > MIN_PIXEL_HEIGHT and
        MIN_ASPECT_RATIO < possibleChar.fltAspectRatio and possibleChar.fltAspectRatio < MAX_ASPECT_RATIO):
        return True
    else:
        return False
    # end if
# end function

###################################################################################################
def findListOfListsOfMatchingChars(listOfPossibleChars):
    listOfListsOfMatchingChars = []                  # this will be the return value

    for possibleChar in listOfPossibleChars:
        listOfMatchingChars = findListOfMatchingChars(possibleChar, listOfPossibleChars)

        listOfMatchingChars.append(possibleChar)

        if len(listOfMatchingChars) < MIN_NUMBER_OF_MATCHING_CHARS:
            continue
        # end if

                # if we get here, the current list passed test as a "group" or "cluster" of matching chars
        listOfListsOfMatchingChars.append(listOfMatchingChars)

        listOfPossibleCharsWithCurrentMatchesRemoved = []

        listOfPossibleCharsWithCurrentMatchesRemoved = list(set(listOfPossibleChars) - set(listOfMatchingChars))

        recursiveListOfListsOfMatchingChars = findListOfListsOfMatchingChars(listOfPossibleCharsWithCurrentMatchesRemoved)

        for recursiveListOfMatchingChars in recursiveListOfListsOfMatchingChars:
            listOfListsOfMatchingChars.append(recursiveListOfMatchingChars)
        # end for

        break       # exit for

    # end for

    return listOfListsOfMatchingChars
# end function

###################################################################################################
def findListOfMatchingChars(possibleChar, listOfChars):
    listOfMatchingChars = []                # this will be the return value

    for possibleMatchingChar in listOfChars:
        if possibleMatchingChar == possibleChar:
            continue
        # end if

        fltDistanceBetweenChars = distanceBetweenChars(possibleChar, possibleMatchingChar)

        fltAngleBetweenChars = angleBetweenChars(possibleChar, possibleMatchingChar)

        fltChangeInArea = float(abs(possibleMatchingChar.intBoundingRectArea - possibleChar.intBoundingRectArea)) / float(possibleChar.intBoundingRectArea)

        fltChangeInWidth = float(abs(possibleMatchingChar.intBoundingRectWidth - possibleChar.intBoundingRectWidth)) / float(possibleChar.intBoundingRectWidth)
        fltChangeInHeight = float(abs(possibleMatchingChar.intBoundingRectHeight - possibleChar.intBoundingRectHeight)) / float(possibleChar.intBoundingRectHeight)

        if (fltDistanceBetweenChars < (possibleChar.fltDiagonalSize * MAX_DIAG_SIZE_MULTIPLE_AWAY) and
            fltAngleBetweenChars < MAX_ANGLE_BETWEEN_CHARS and
            fltChangeInArea < MAX_CHANGE_IN_AREA and
            fltChangeInWidth < MAX_CHANGE_IN_WIDTH and
            fltChangeInHeight < MAX_CHANGE_IN_HEIGHT):

            listOfMatchingChars.append(possibleMatchingChar)
        # end if
    # end for

    return listOfMatchingChars
# end function

###################################################################################################
def distanceBetweenChars(firstChar, secondChar):

    intX = abs(firstChar.intCenterX - secondChar.intCenterX)
    intY = abs(firstChar.intCenterY - secondChar.intCenterY)

    return math.sqrt((intX ** 2) + (intY ** 2))
# end function

###################################################################################################
def angleBetweenChars(firstChar, secondChar):
    fltAdj = float(abs(firstChar.intCenterX - secondChar.intCenterX))
    fltOpp = float(abs(firstChar.intCenterY - secondChar.intCenterY))

    if fltAdj != 0.0:
        fltAngleInRad = math.atan(fltOpp / fltAdj)
    else:
        fltAngleInRad = 1.5708
    # end if

    fltAngleInDeg = fltAngleInRad * (180.0 / math.pi)

    return fltAngleInDeg
# end function

###################################################################################################
def removeInnerOverlappingChars(listOfMatchingChars):
    listOfMatchingCharsWithInnerCharRemoved = []                # this will be the return value

    for currentChar in listOfMatchingChars:
        for otherChar in listOfMatchingChars:
            if currentChar.contour.all() == otherChar.contour.all():
                if distanceBetweenChars(currentChar, otherChar) < (currentChar.fltDiagonalSize * MIN_DIAG_SIZE_MULTIPLE_AWAY):

                    if currentChar.intBoundingRectArea < otherChar.intBoundingRectArea:
                        if currentChar in listOfMatchingCharsWithInnerCharRemoved:
                            listOfMatchingCharsWithInnerCharRemoved.remove(currentChar)
                        # end if
                    else:
                        if otherChar in listOfMatchingCharsWithInnerCharRemoved:
                            listOfMatchingCharsWithInnerCharRemoved.remove(otherChar)
                        # end if
                    # end if
                # end if
            # end if
        # end for
    # end for

    return listOfMatchingCharsWithInnerCharRemoved
# end function

###################################################################################################
def recognizeCharsInPlate(imgThresh, listOfMatchingChars):
    strChars = ""               # this will be the return value, the chars in the lic plate

    height, width = imgThresh.shape

    imgThreshColor = np.zeros((height, width, 3), np.uint8)

    listOfMatchingChars.sort(key = lambda matchingChar: matchingChar.intCenterX)        # sort chars from left to right

    cv2.cvtColor(imgThresh, cv2.COLOR_GRAY2BGR, imgThreshColor)

    for currentChar in listOfMatchingChars:
        pt1 = (currentChar.intBoundingRectX, currentChar.intBoundingRectY)
        pt2 = ((currentChar.intBoundingRectX + currentChar.intBoundingRectWidth), (currentChar.intBoundingRectY + currentChar.intBoundingRectHeight))

        cv2.rectangle(imgThreshColor, pt1, pt2, Main.SCALAR_GREEN, 2)

        imgROI = imgThresh[currentChar.intBoundingRectY : currentChar.intBoundingRectY + currentChar.intBoundingRectHeight,
                           currentChar.intBoundingRectX : currentChar.intBoundingRectX + currentChar.intBoundingRectWidth]

        imgROIResized = cv2.resize(imgROI, (RESIZED_CHAR_IMAGE_WIDTH, RESIZED_CHAR_IMAGE_HEIGHT))

        npaROIResized = imgROIResized.reshape((1, RESIZED_CHAR_IMAGE_WIDTH * RESIZED_CHAR_IMAGE_HEIGHT))

        npaROIResized = np.float32(npaROIResized)

        retval, npaResults, neigh_resp, dists = kNearest.findNearest(npaROIResized, k = 1)              # finally we can call findNearest !!!

        strCurrentChar = str(chr(int(npaResults[0][0])))

        strChars = strChars + strCurrentChar                        # append current char to full string

    # end for

    if Main.showSteps == True:
        cv2.imshow("10", imgThreshColor)
    # end if

    return strChars
# end function