531402 五、發明說明（1) 本發明係有關於一種以影像處理的方式在眼部影像上 追蹤眼睛虹膜中心點位置的方法。 眼位追蹤是醫學上研究眼睛運動的技術，也是視線追 =(E y e G a z e T r a c k i n g )的關鍵技術，關係著視線追蹤所 到的精確度。眼位追蹤技術所要達成的目的可以用一 二兩來形容：所視即所得；你的眼睛所注視到的物體會立 產生反應’像疋電腦視窗程式的駐點反應等等。它能廉 ，人機介面、多媒體應用、虛擬實境等，能加快控弗7 g 後=封也能打破手腳能及的距離限制，對於肢體殘障者也 有幫助，並且尚有許多不同領域的應用。 縱技術有許多種，包含有眼電法 法（cLnea’and P^^netlC SearCh C〇il)以及角膜反射 、cornea ana pupi1 ref 1p「十ίnn、笪發 a 丄 $強健度（robust)上都尚待、、口， f缺點，但 利用眼睛各部分對光線有：同$ H J非侵入式的技術， 部反射回來的光線形成眼=$反^率，以攝影機接收眼 定眼睛的運動與方位。角:=象、、’再以影像處理的方式決 種··紅外線類與可見光類。、于法又以光線種類分為兩 紅外線類由一個低功銮 目艮部，利用鞏膜與角膜右私丄、’工、、、投射源投射紅外線到 分因為狀態類似黑體輕射=的紅外線反射率，而瞳孔部 射的孔洞，所以反射率較低，因此531402 V. Description of the invention (1) The present invention relates to a method for tracking the position of the center point of the eye iris on the eye image by means of image processing. Eye tracking is a medical technology for studying eye movements, and it is also a key technology for eye tracking (E y e G a z e T r c k i n g), which is related to the accuracy of eye tracking. The purpose of eye tracking technology can be described in one or two ways: what you see is what you get; what your eye looks at will react immediately, like a stagnation reaction of a computer window program, and so on. It can be cheap, with human-machine interface, multimedia applications, virtual reality, etc. It can speed up the control of 7 g. Back = seal can also break the distance limit that can be reached by hands and feet. It is also helpful for people with physical disabilities, and there are still many applications in different fields . There are many types of longitudinal techniques, including the electro-optical method (cLnea'and P ^^ netlC SearCh Coil), and corneal reflex, cornea ana pupi1 ref 1p, "Shi nnnn, 笪 发 a 丄 $, robustness (robust). The shortcomings of mouth, mouth, and f are disadvantages, but the use of various parts of the eye to the light has the following: the same as the $ HJ non-invasive technology, the light reflected by the part forms the eye = $ reflection rate, and the camera receives the eye to determine the eye movement and orientation .Angle: = Elephant ,, and then use the image processing method to determine the species ... Infrared and visible light. Yufa is divided into two types of infrared light by the type of light from a low-power eyelid, using the sclera and the right cornea The private, 'work ,,', and projection sources project infrared light to the point because the state is similar to the infrared reflectance of the black body light shot =, and the pupil shot by the hole, so the reflectance is low, so
531402 五、發明說明（2) 在攝影機接收到的影像上，目童孔會是一個低党度的圓形。 在接收到的紅外線影像上再利用各種影像處理的技術找出 瞳孔中心點。紅外線類的缺點在於必須使用紅外線投射源 以及紅外線攝影機，價袼昂貴；且紅外線影像仍然會有反 光及眼睫毛干擾的困擾，必須要非常乾淨的眼部影像才會 有好的效果。 可見光類由於使用—般攝影機，所以價錢便宜；可見 光類一般使用黑白影像作處理’由於黑白影像中虹膜與瞳 孔的對比不明顯，因此眼位追蹤的對象會是虹膜而不是瞳 孔；好處是虹膜的大小不會變’但比起紅外線影像而言， 可見光影像的干擾遠較紅外線影像來的大。可見光影像上 用做追蹤虹膜中心點的影像處理技術與用在紅外線影像上" 的類似，包含有霍夫轉換（Hough transform)、可變形樣 版（Deformable template)、卡曼濾波器法（Kalman filter)、灰階閾值法（gray level thresdhold)等等，但 這些方法都不夠強健，遇到眼睫毛濃密、反光嚴重、眼睛 張開幅度狹小等等的情況時就無法使用。 本發明的目的在於提供一強健的影像處理方法，克服 眼睫毛濃密、反光嚴重、眼睛張開幅度狹小等等的困難， 能準確的追蹤、定位出眼睛虹膜的中心點，並提供極高的 解析度與效能。 本發明之眼位追蹤方法的技術内容如下：在受試者頭531402 V. Description of the invention (2) In the image received by the camera, the eye hole will be a circle with a low party degree. Based on the received infrared image, various image processing techniques are used to find the center point of the pupil. The disadvantage of infrared is that infrared projection sources and infrared cameras must be used, which is expensive. In addition, infrared images still suffer from reflections and eyelash interference. A very clean eye image is required for good results. Visible light uses a general camera, so the price is cheap; visible light generally uses black and white images for processing. Because the contrast between the iris and the pupil in the black and white image is not obvious, the eye tracking object will be the iris instead of the pupil; the benefit is the iris The size does not change, but compared to infrared images, the interference of visible light images is much larger than that of infrared images. The image processing technology used to track the center point of the iris on the visible light image is similar to that used on the infrared image. It includes Hough transform, Deformable template, and Kalman filter method. filter), gray level threshold (gray level thresdhold), etc., but these methods are not strong enough, when faced with thick eyelashes, severe reflection, narrow eye opening and so on, it can not be used. The purpose of the present invention is to provide a robust image processing method, which can overcome the difficulties of dense eyelashes, severe reflection, narrow eye opening, etc., can accurately track and locate the center point of the eye iris, and provide extremely high resolution. And effectiveness. The technical content of the eye position tracking method of the present invention is as follows:
531402 五、發明說明（3) 部架設一攝影機，攝影機的位置是位於眼睛前方；由於攝 影機是固定在頭部，所以攝影機與眼睛的相對位置是固定 不變的，在這種情況下，虹膜可以被視為是一個半徑大小 不變的低灰階值圓盤。架設好攝影機後，就可以開始擷取 影像，進入起始步驟。 輪 起始步驟：在取得第一張眼睛張開的眼部影像後，顯 示在電腦螢幕上，以滑鼠在影像上拉出虹膜直徑，接著以 虹膜直徑長度為參數，設定型變濾波器，而後進入追蹤步 驟。型變濾波器之定義如圖示。 圖一、為型變濾波器，其數值分布以影像之亮度表示；狀 似一車輪，在二維影像空間上為一圓心對稱的圖 形。 圖二、是通過型變濾波器中心點之橫切面剖面圖，由兩個 反向的波浪狀波形組成。 圖三、是圖二之右半部成分，為一波浪狀之波形。波浪狀 之最高值點與最低值點在空間上的距離為虹模半徑 長度的5 0 %以内。 追蹤步驟：起始步驟之後取得的眼部影像，都與起始 步驟所設定的型變滤波器作捲積（c ο n v ο 1 u t i ο η )，接著在 得到的輸出影像上找最低值點，而最低值點的座標位置就 是虹膜的中心點位置。 圖四、是眼位追蹤方法的流程圖。531402 V. Description of the invention (3) A camera is set up, and the position of the camera is in front of the eyes. Since the camera is fixed on the head, the relative position of the camera and the eyes is fixed. In this case, the iris can It is considered to be a low-gray value disc with a constant radius. After setting up the camera, you can start capturing images and enter the initial step. The initial step of the round: after obtaining the first eye image with the eyes open, display it on the computer screen, use the mouse to pull the iris diameter on the image, and then use the iris diameter length as a parameter to set the deformation filter. Then enter the tracking step. The definition of the variable filter is shown in the figure. Figure 1 shows a type-change filter, whose numerical distribution is represented by the brightness of the image; it looks like a wheel, and is a circle-symmetric image in a two-dimensional image space. Figure 2 is a cross-sectional view of the center point of the pass-through filter, which consists of two opposite wave-like waveforms. Figure 3 is the right half of Figure 2, which is a wavy waveform. The distance between the highest point of the wavy point and the lowest point in space is within 50% of the radius of the rainbow pattern. Tracking step: The eye image obtained after the initial step is convolved with the deformation filter set in the initial step (c ο nv ο 1 uti ο η), and then the lowest value point is found on the obtained output image , And the coordinate position of the lowest point is the position of the center point of the iris. Figure 4 is a flowchart of the eye tracking method.
第6頁 531402 五、發明說明（4) 本發明所使用之型變濾波器及步驟，已於前文與各圖 示中闡明，然其並非用以限定本發明，任何熟悉本技術領 域者，在不脫離本發明之精神下，當可做更動與調整。因 此本發明之保護範圍當視後附之申請專利範圍為準。 kPage 6 531402 V. Description of the invention (4) The variable filter and steps used in the present invention have been explained in the foregoing and the drawings, but they are not intended to limit the present invention. Anyone familiar with the technical field, Changes and adjustments can be made without departing from the spirit of the invention. Therefore, the protection scope of the present invention shall be subject to the scope of the attached patent application. k
第7頁 531402 圖式簡單說明 第8頁Page 7 531402 Schematic description Page 8