Automation of gross photography using a remote-controlled digital camera system

Archives of Pathology & Laboratory Medicine, Jun 2003 by Park, Rae-Woong, Eom, Joon-Hoe, Byun, Ho-Yong, Park, Peom, Et al

The focusing length for macrophotography should also be considered. As Belanger et al4 stated previously, "if macrophotography requires changing a lens, the system will not be used or will be rapidly damaged." The most important consideration is whether the digital camera can be controlled remotely. Digital cameras using a Fujitsu chipset (Fujitsu, Tokyo, Japan) for their central processing unit share a common data-transfer protocol. This protocol and command-line tools running on UNIX, Windows 95/NT, and DOS are available on the Internet (http://photopc.sourceforge.net). With these considerations, the Nikon Coolpix 995 model was selected because it has 3.34 megapixels in resolution, 2 cm in macrophotography focusing length, and very good natural color expression.

Remote Control of Digital Camera and Control Board

Although camera vendors often supply remote-control software for their cameras, this software is not customized for use in the pathology department. Most digital cameras support both a serial connection and universal serial bus (USB) connection for image transfer. Serial connections are limited by their lower communication speed, usually around 7.2 kB/s. When you consider that the file size of a 3.15-megapixel image is about 1 MB, it is not practical to download images of this file size through a serial line. The USB line is much more suitable for image transfer because it has a communication speed of 10 megabits/s, equivalent to 1.25 MB/s, in USB 1.1 protocol. Unfortunately, the Coolpix 995, as well as most other digital cameras, can be controlled only through a serial line. Therefore, we decided to make a control board that could switch between a serial line for camera control and a USB line for image downloading. As a detailed review of the control board circuit is beyond the scope of this article, the following is a brief description. The control board provides a power supply to the digital camera, switching between the serial line and the USB line, and is attached to a foot switch input signal-- processing unit to allow for hands-free operation. The control board was made in cooperation with electronic engineers from Humintec Co (Suwon, Korea). Because the digital camera must be connected to 4 complex cables, including the power supply cable, a serial cable, a USB cable, and a video-out cable, we assembled the digital camera in a metal box, and all the cables were arranged in a shielded cable (Figure 2). With this control board, we could control the digital camera's zoom and shutter, as well as switch between the macrophotography mode and the common photography mode through a 3-action foot switch.

Specimen Number Recognition and Image Number Mapping

Almost all gross photographs show a pathology number label in the center of a ruler. The number on the ruler is the only way to recognize the specimen number when sorting, labeling, and filing the photographs. The job of making and manually applying these labeling stickers is tedious. Moreover, it is difficult to remove an old sticker from a ruler. It would be desirable, then, to devise a system that automatically recognizes the specimen number and saves the images according to that number. Under such a system, much of the tediousness of gross photography, such as sticker labeling, sticker removal, and image sorting will disappear. For this project, a barcode reader and printer was used. When gross photographs are taken, the barcode reader picks up the pathology number, which is recorded as a barcode on the pathology request slip or on the specimen container (Figure 3). The digital image is then saved temporarily onto the digital camera's compact flash memory card, and the image file is assigned a number by the digital camera. The images are saved in standard Joint Photographic Expert Group (JPEG) format using the fine compression mode, which requires approximately 960 to 1200 kB of memory space for a 3.15 megapixel image (2048 x 1536 pixels). The time and date the image was taken, as well as the pathology number read through the barcode reader, are also recorded in the system's database. When a predetermined time (10 minutes in our case) passes without any action, the system's control board switches from the serial connection to the USB connection, and the images are downloaded from the camera's compact flash memory card to the image server's hard disk drive. Because each image file has its own time and date information, the specimen number can be recognized by comparing the time and date the image file was created with the system's database records. After the images are downloaded, the connection is switched back to the serial connection mode, and the camera is again ready for use. This automatic specimen number recognition system has had a great impact on gross photographic workflow.