void CharacterAnalysis::filterByOuterMask(TextContours& textContours)
{
float MINIMUM_PERCENT_LEFT_AFTER_MASK = 0.1;
float MINIMUM_PERCENT_OF_CHARS_INSIDE_PLATE_MASK = 0.6;
if (this->pipeline_data->hasPlateBorder == false)
return;
cv::Mat plateMask = pipeline_data->plateBorderMask;
Mat tempMaskedContour = Mat::zeros(plateMask.size(), CV_8U);
Mat tempFullContour = Mat::zeros(plateMask.size(), CV_8U);
int charsInsideMask = 0;
int totalChars = 0;
vector<bool> originalindices;
for (unsigned int i = 0; i < textContours.size(); i++)
originalindices.push_back(textContours.goodIndices[i]);
for (unsigned int i=0; i < textContours.size(); i++)
{
if (textContours.goodIndices[i] == false)
continue;
totalChars++;
tempFullContour = Mat::zeros(plateMask.size(), CV_8U);
drawContours(tempFullContour, textContours.contours, i, Scalar(255,255,255), CV_FILLED, 8, textContours.hierarchy);
bitwise_and(tempFullContour, plateMask, tempMaskedContour);
float beforeMaskWhiteness = mean(tempFullContour)[0];
float afterMaskWhiteness = mean(tempMaskedContour)[0];
if (afterMaskWhiteness / beforeMaskWhiteness > MINIMUM_PERCENT_LEFT_AFTER_MASK)
{
charsInsideMask++;
textContours.goodIndices[i] = true;
}
}
if (totalChars == 0)
{
textContours.goodIndices = originalindices;
return;
}
// Check to make sure that this is a valid box. If the box is too small (e.g., 1 char is inside, and 3 are outside)
// then don't use this to filter.
float percentCharsInsideMask = ((float) charsInsideMask) / ((float) totalChars);
if (percentCharsInsideMask < MINIMUM_PERCENT_OF_CHARS_INSIDE_PLATE_MASK)
{
textContours.goodIndices = originalindices;
return;
}
}
void CharacterAnalysis::filterContourHoles(TextContours& textContours)
{
for (uint i = 0; i < textContours.size(); i++)
{
if (textContours.goodIndices[i] == false)
continue;
textContours.goodIndices[i] = false; // Set it to not included unless it proves valid
int parentIndex = textContours.hierarchy[i][3];
if (parentIndex >= 0 && textContours.goodIndices[parentIndex])
{
// this contour is a child of an already identified contour. REMOVE it
if (this->config->debugCharAnalysis)
{
cout << "filterContourHoles: contour index: " << i << endl;
}
}
else
{
textContours.goodIndices[i] = true;
}
}
}
// Goes through the contours for the plate and picks out possible char segments based on min/max height
void CharacterAnalysis::filterByBoxSize(TextContours& textContours, int minHeightPx, int maxHeightPx)
{
float idealAspect=config->charWidthMM / config->charHeightMM;
float aspecttolerance=0.25;
for (uint i = 0; i < textContours.size(); i++)
{
if (textContours.goodIndices[i] == false)
continue;
textContours.goodIndices[i] = false; // Set it to not included unless it proves valid
//Create bounding rect of object
Rect mr= boundingRect(textContours.contours[i]);
float minWidth = mr.height * 0.2;
//Crop image
//cout << "Height: " << minHeightPx << " - " << mr.height << " - " << maxHeightPx << " ////// Width: " << mr.width << " - " << minWidth << endl;
if(mr.height >= minHeightPx && mr.height <= maxHeightPx && mr.width > minWidth)
{
float charAspect= (float)mr.width/(float)mr.height;
//cout << " -- stage 2 aspect: " << abs(charAspect) << " - " << aspecttolerance << endl;
if (abs(charAspect - idealAspect) < aspecttolerance)
textContours.goodIndices[i] = true;
}
}
}
void CharacterAnalysis::filter(Mat img, TextContours& textContours)
{
static int STARTING_MIN_HEIGHT = round (((float) img.rows) * config->charAnalysisMinPercent);
static int STARTING_MAX_HEIGHT = round (((float) img.rows) * (config->charAnalysisMinPercent + config->charAnalysisHeightRange));
static int HEIGHT_STEP = round (((float) img.rows) * config->charAnalysisHeightStepSize);
static int NUM_STEPS = config->charAnalysisNumSteps;
int bestFitScore = -1;
vector<bool> bestIndices;
for (int i = 0; i < NUM_STEPS; i++)
{
//vector<bool> goodIndices(contours.size());
for (uint z = 0; z < textContours.size(); z++) textContours.goodIndices[z] = true;
this->filterByBoxSize(textContours, STARTING_MIN_HEIGHT + (i * HEIGHT_STEP), STARTING_MAX_HEIGHT + (i * HEIGHT_STEP));
int goodIndices = textContours.getGoodIndicesCount();
if ( goodIndices == 0 || goodIndices <= bestFitScore) // Don't bother doing more filtering if we already lost...
continue;
this->filterContourHoles(textContours);
goodIndices = textContours.getGoodIndicesCount();
if ( goodIndices == 0 || goodIndices <= bestFitScore) // Don't bother doing more filtering if we already lost...
continue;
int segmentCount = textContours.getGoodIndicesCount();
if (segmentCount > bestFitScore)
{
bestFitScore = segmentCount;
bestIndices = textContours.getIndicesCopy();
}
}
textContours.setIndices(bestIndices);
}
void CharacterAnalysis::filterBetweenLines(Mat img, TextContours& textContours, vector<TextLine> textLines )
{
static float MIN_AREA_PERCENT_WITHIN_LINES = 0.88;
static float MAX_DISTANCE_PERCENT_FROM_LINES = 0.15;
if (textLines.size() == 0)
return;
vector<Point> validPoints;
// Create a white mask for the area inside the polygon
Mat outerMask = Mat::zeros(img.size(), CV_8U);
for (uint i = 0; i < textLines.size(); i++)
fillConvexPoly(outerMask, textLines[i].linePolygon.data(), textLines[i].linePolygon.size(), Scalar(255,255,255));
// For each contour, determine if enough of it is between the lines to qualify
for (uint i = 0; i < textContours.size(); i++)
{
if (textContours.goodIndices[i] == false)
continue;
float percentInsideMask = getContourAreaPercentInsideMask(outerMask,
textContours.contours,
textContours.hierarchy,
(int) i);
if (percentInsideMask < MIN_AREA_PERCENT_WITHIN_LINES)
{
// Not enough area is inside the lines.
if (config->debugCharAnalysis)
cout << "Rejecting due to insufficient area" << endl;
textContours.goodIndices[i] = false;
continue;
}
// now check to make sure that the top and bottom of the contour are near enough to the lines
// First get the high and low point for the contour
// Remember that origin is top-left, so the top Y values are actually closer to 0.
Rect brect = boundingRect(textContours.contours[i]);
int xmiddle = brect.x + (brect.width / 2);
Point topMiddle = Point(xmiddle, brect.y);
Point botMiddle = Point(xmiddle, brect.y+brect.height);
// Get the absolute distance from the top and bottom lines
for (uint i = 0; i < textLines.size(); i++)
{
Point closestTopPoint = textLines[i].topLine.closestPointOnSegmentTo(topMiddle);
Point closestBottomPoint = textLines[i].bottomLine.closestPointOnSegmentTo(botMiddle);
float absTopDistance = distanceBetweenPoints(closestTopPoint, topMiddle);
float absBottomDistance = distanceBetweenPoints(closestBottomPoint, botMiddle);
float maxDistance = textLines[i].lineHeight * MAX_DISTANCE_PERCENT_FROM_LINES;
if (absTopDistance < maxDistance && absBottomDistance < maxDistance)
{
// It's ok, leave it as-is.
}
else
{
textContours.goodIndices[i] = false;
if (config->debugCharAnalysis)
cout << "Rejecting due to top/bottom points that are out of range" << endl;
}
}
}
}
// Goes through the contours for the plate and picks out possible char segments based on min/max height
// returns a vector of indices corresponding to valid contours
void CharacterAnalysis::filterByParentContour( TextContours& textContours)
{
vector<int> parentIDs;
vector<int> votes;
for (uint i = 0; i < textContours.size(); i++)
{
if (textContours.goodIndices[i] == false)
continue;
textContours.goodIndices[i] = false; // Set it to not included unless it proves
int voteIndex = -1;
int parentID = textContours.hierarchy[i][3];
// check if parentID is already in the lsit
for (uint j = 0; j < parentIDs.size(); j++)
{
if (parentIDs[j] == parentID)
{
voteIndex = j;
break;
}
}
if (voteIndex == -1)
{
parentIDs.push_back(parentID);
votes.push_back(1);
}
else
{
votes[voteIndex] = votes[voteIndex] + 1;
}
}
// Tally up the votes, pick the winner
int totalVotes = 0;
int winningParentId = 0;
int highestVotes = 0;
for (uint i = 0; i < parentIDs.size(); i++)
{
if (votes[i] > highestVotes)
{
winningParentId = parentIDs[i];
highestVotes = votes[i];
}
totalVotes += votes[i];
}
// Now filter out all the contours with a different parent ID (assuming the totalVotes > 2)
for (uint i = 0; i < textContours.size(); i++)
{
if (textContours.goodIndices[i] == false)
continue;
if (totalVotes <= 2)
{
textContours.goodIndices[i] = true;
}
else if (textContours.hierarchy[i][3] == winningParentId)
{
textContours.goodIndices[i] = true;
}
}
}
