From e4d755c00d8cca674e3f57d9711d8622a7ce7e63 Mon Sep 17 00:00:00 2001
From: Epicalert <epicalert@protonmail.com>
Date: Mon, 7 Jun 2021 02:05:48 +0800
Subject: [PATCH] Improve iris detection

This commit makes the following changes to the iris detection:
- Use Scharr instead os Sobel algorithm for image gradient
- Apply Gaussian blur to eye image before processing
- Scale down the eye image if too large
---
 src/cv.cpp  |  6 ++----
 src/eye.cpp | 23 ++++++++++++++++-------
 2 files changed, 18 insertions(+), 11 deletions(-)

diff --git a/src/cv.cpp b/src/cv.cpp
index 146ca14..dfdee0d 100644
--- a/src/cv.cpp
+++ b/src/cv.cpp
@@ -112,7 +112,8 @@ void cvFrame() {
 
 		//get ROI for eyes
 		float eyeWidth = landmarks[biggestFace][45].x - landmarks[biggestFace][42].x;
-		cv::Rect eyeRect(landmarks[biggestFace][42].x, landmarks[biggestFace][42].y - eyeWidth / 2, eyeWidth, eyeWidth);
+		cv::Rect eyeRect(landmarks[biggestFace][42].x,
+				landmarks[biggestFace][42].y - eyeWidth / 2, eyeWidth, eyeWidth);
 
 		cv::rectangle(frame, eyeRect, cv::Scalar(255, 255, 255));
 
@@ -121,9 +122,6 @@ void cvFrame() {
 
 		glm::vec2 eyeVector = eyeDirection(eyeROI);
 
-		cv::imshow("eye", eyeROI);
-		cv::waitKey(1);
-
 		//send control information to graphics
 		float faceSize = landmarks[biggestFace][14].x - landmarks[biggestFace][2].x;
 
diff --git a/src/eye.cpp b/src/eye.cpp
index ead36e7..75514fd 100644
--- a/src/eye.cpp
+++ b/src/eye.cpp
@@ -55,16 +55,22 @@ cv::Point2f derivativeFunction(cv::Point2f c, cv::Mat gX, cv::Mat gY) {
 }
 
 glm::vec2 eyeDirection(cv::Mat roi) {
-	cv::Mat gX, gY;
-	cv::Sobel(roi, gX, CV_32F, 1, 0);
-	cv::Sobel(roi, gY, CV_32F, 0, 1);
+	cv::Mat gX, gY, eyeMat;
+	if(roi.rows > 32) {
+		cv::pyrDown(roi, eyeMat, cv::Size(roi.cols / 2, roi.rows / 2));
+	} else {
+		cv::GaussianBlur(roi, eyeMat, cv::Size(7,7), 1);
+	}
 
-	float stepSize = roi.rows / 10;
+	cv::Scharr(eyeMat, gX, CV_32F, 1, 0);
+	cv::Scharr(eyeMat, gY, CV_32F, 0, 1);
+
+	float stepSize = eyeMat.rows / 10;
 	float maxVal = 0;
 
 	cv::Point2f irisPosition;
 	for(int i = 0; i < 32; i++) {
-		cv::Point2f c(std::rand() % roi.cols, std::rand() % roi.rows); //start at a random point
+		cv::Point2f c(std::rand() % eyeMat.cols, std::rand() % eyeMat.rows); //start at a random point
 		
 		float prevVal = 0;
 		for(int j = 0; j < 8; j++) {
@@ -74,7 +80,7 @@ glm::vec2 eyeDirection(cv::Mat roi) {
 
 			for(int k = 0; k < 6; k++) {
 				cv::Point2f newC = c + gradient * stepSize;
-				if (newC.x < 0 || newC.x > roi.cols || newC.y < 0 || newC.y > roi.rows) continue;
+				if (newC.x < 0 || newC.x > eyeMat.cols || newC.y < 0 || newC.y > eyeMat.rows) continue;
 
 				float newVal = objectiveFunction(newC, gX, gY);
 				if (newVal > prevVal) {
@@ -95,7 +101,10 @@ glm::vec2 eyeDirection(cv::Mat roi) {
 		}
 	}
 
-	cv::drawMarker(roi, irisPosition, cv::Scalar(128,128,128));
+	cv::drawMarker(eyeMat, irisPosition, cv::Scalar(128,128,128));
+	
+	cv::imshow("eye", eyeMat);
+	cv::waitKey(1);
 
 	// convert result to vector for graphics
 	return glm::vec2(