The digital microscope hardware

ISSN: 1693-6930 TELKOMNIKA Vol. 9, No. 3, December 2011 : 565 – 574 566 hospitals, health agencies and in educational institutions. These microscopes were acquired years ago before digital microscopes are in the market. In order to enhance the value and the usefulness of an analog microscope, it is proposed to convert the analog microscope into a digital microscope. This is done by attaching an additional hardware to the existing manual microscope which also connects it to a computer. Computer software is written on a computer so that the microscope becomes a digital microscope. The software developed for the digital microscope is basically a digital image processing software. The software is capable of capturing image and carrying out basic image processing task. The term digital image processing is normally used with respect to the transformation of images into digital forms and processes them using a digital computer. The digital image processing methods can be categorized into two basic categories: improving the quality of images as information for human interpretation, and image data processing for machine perception [7][8]. Methods in the first category include digital image processing methods normally used for enhancing digital images. Methods in the second category include methods for image analysis and image recognition. The digital image analysis is associated with the description of the contents of the image [8]. The digital image recognition is carried out by understanding the characteristics or features of the image. These features can be derived in the spatial domain or frequency domain [8]. Spatial features include: color such as mean, standard deviation, histogram, area, perimeter, compactness, circumference, edge direction, strength and contours [9][10][11][12][13][14][15]. A number of image enhancement methods in the frequency domain or in spatial domain have been studied, including contrast stretching [15] and fuzzy hyperbolization [16][17]. A comprehensive review of the image enhancement methods is reported in [18]. A number of digital microscopes have been developed and reported in literatures. Çatalyürek et. al.[19] developed a virtual microscope which enable person on a client computer to access images on the network’s server. A portable digital microscope is developed and reported by Tai-Shan et.al.[20]. However, the resolution and magnification of this microscope is low. Anand et.al.[21] reported the development of a compact digital holographic microscope. An Integrated Auto-focusing System for Biomedical Digital Microscope is reported by Gang et.al.[22]. In this paper, the development of a high resolution, high magnification digital microscope is reported.

2. The development of the digital microscope

The development of the digital microscope is carried out in two stages, the hardware and software system. The process is discussed in the following sections.

2.1. The digital microscope hardware

The hardware of the digital microscope consists of an analog microscope, a light source, a camera and the camera housing. The camera replaces the position of the user’s eye. The image of the observed object is focused on the camera. The image of the observed object is continuously displayed on the user’s computer screen. The user captures the image of the observed object by selecting the appropriate menu on the computer screen. Once the image is captured, it can be stored or process depending on the user need. In this research, the analog biological microscope has been selected as the case study due to its widespread use, low cost and flexibility. The micsocope has a magnification range from 20x up to 1600x. In order to obtain the best digital camera to be embedded to the manual microscope, a number of digital cameras were evaluated. From the evaluation it was decided to use a Prolink digital camera. This camera supports image resolution of 320x240, 640x480, 800x600, 1024x768, 1280x1024, 1600x1200, 2000x1600, and 2592x1944 pixels. A camera housing was designed and made for the Prolink camera so that the camera can be mounted on the eyepiece tube of the analog microscope, see Figure 1a. The connection between the camera and the computer is through the USB port of the computer. To illuminate the observed object a LED is mounted under the microscope base. The illumination of the LED is adjustable to obtain the best illumination intensity. The proposed digital microscope is designed to have two modes of operations, simple mode and normal mode. In the simple mode the digital microscope acts as a plug and play TELKOMNIKA ISSN: 1693-6930 The Digital Microscope and Its Image Processing Utility Sri Hartati 567 device with default resolution setting. The user may capture image from the microscope by pressing a button mounted on the camera house. In this mode, the captured image is stored in a file and the image processing software will read the image captured by the microscope from the file. In the normal mode, the support software needs to be installed. The support software enables user to set image resolution, capture image from the microscope through the software and performing digital image processing tasks on the captured image. The overall digital microscope developed in this research is shown in Figure 1b. The setup of the digital microscope is shown in Figure 1c. Figure 1. From left to right a Camera housing for the digital microscope, b The digital Microscope and c the setup of the digital microscope.

2.2. The digital microscope software