디지털 홀로그램 현미경에 의한 적혈구 자동 추출 및 분석

Abstract

In this thesis, we have applied the marker-controlled watershed algorithm to achieve automated segmentation of the red blood cells(RBCs) phase images. The phase image of RBCs is obtained by using off-axis digital holographic microscopy. In order to calculate a correct phase value of RBC and analyze it quantitatively, it is important to perform a background subtraction of the phase images and set 0° value to the background parts of the RBCs phase image for the purpose of comparing the RBCs phase image. The most important process of segmentation based on marker-controlled watershed is achieving an accurate locatization of internal and external markers. Here, we first obtain the binary image via Ostu algorithm. Then, we apply the morphological operation to the binary image to get the internal markers, and we use the distance transform combined with the watershed algorithm to generate external markers based on internal markers. Finally, combining the internal and external markers, we modify the original gradient image and apply the watershed algorithm to them. By appropriately identifying the internal and external markers, the problems of over-segmentation and under-segmentation are avoided. Furthermore, the inside and outside parts of RBCs phase image can also be segmented by using the marker-controlled watershed combined with our method which can identify the internal and external markers appropriately. Our experimental result shows that the proposed procedure achieves good performance in terms of segmenting RBCs. After segmentation, the properties of RBCs such as mean phase value, projected surface area, dry mass and spherificity coefficient can be obtained and analyzed in deatil.