Implementation of Digital Camera Technology with Cobra Seal

ABSTRACT

Various methods for verifying a Cobra seal exist. Aquila produced the first version of AutoCobra in 1995, a system consisting of a digital camera and laptop computer. The laptop contained Aquila software designed to download the Cobra Seal images from the camera and perform seal verification by comparing a new image of a seal to a reference image taken when the seal was originally installed. The laptop also featured an onboard printer, allowing seal images to be printed at any time. However, the need for immediate image display and comparison prompted Aquila to develop a manual seal verification system, the Cobra Seal II. The Cobra II system used a Still Video Camera which recorded images on a video floppy disk and immediately displayed images on a viewfinder window (the Canon RC-250 camera) and Sony black-and-white video graphic printer, both of which are now obsolete. This year, Aquila released the Cobra III Seal Imaging System, which maintains the functionality of the Cobra II system and includes: 1) a Casio QV-30 digital camera, 2) Casio DP-8000 video color printer with 230-115VAC isolation transformer, 3) Aquila proprietary optics, 4) illumination and alignment accessory, and 5) a portable power pack.

The Casio QV-30 camera has a built-in liquid crystal color monitor that can be used as a viewfinder when photographing seal images and can also be used to display stored images. The QV-30 can digitally store up to 96 seal images, which may be archived using the DP-8000 printer or transferred to a PC using a MS Windows based user interface program. Aquila proprietary optics, seal illumination, and seal receptacle are designed to provide a consistent image over a wide range of fiber optic length and seal construction. The real time video display provides the inspector the opportunity for manipulation of the seal in the camera body to optimize the image. Once the captured images are printed using the DP-8000 printer (at 297 x 446 dpi), the seal images can then be manually reviewed. This paper discusses the controversy regarding manual versus automatic seal verification and its impact on the design and production of verification systems.

INTRODUCTION

New advances in Digital camera technology have made in situ verification of Cobra seals possible in real time. Previous digital and analog camera technologies allowed Cobra seal imaging to be verified both manually and electronically, but fell short in real time feedback to the inspector. The concept of manual review, aided with immediate imaging, has made inspection both fast and accurate.

HISTORY

The Cobra seal is a low cost, general purpose, and long term safeguard seal which is easy to use and versatile. Yet, verification of the seals has always posed a problem because the various methods of verification proved to be too time consuming and often inaccurate.

Early analog manual review techniques relied on hardware with limited image display and printed quality. Using early analog camera technology, images were taken, recorded, and then played to a NTSC video system. Archiving images was done on small floppy disks that were proprietary to the camera, and were soon obsolete after only a year of production.

Later digital camera technology was also limited by the fact that the optical system was of a laboratory design in which very fine and minute adjustments were necessary, rendering it unsuitable for field use. In addition, emerging digital camera technology suffered quality problems, only giving a resolution equal to its analog counterpart. Although these cameras are still commercially available, they suffer the disadvantage of requiring imaging and saving before the picture can be seen. Accuracy and reliability were also factors in both systems, causing the inspection process to remain difficult and time consuming.

Figure 1:
Cobra III Seal Imaging System

SYSTEM DESCRIPTION

The Cobra III Seal Imaging System (Figure 1) is a highly portable seal inspection station suitable for on-site inspections. It is designed to photograph, view, and print images of seals for review and tamper inspection. The Cobra III Seal Imaging System is intended to replace the Cobra II System which used the now obsolete Canon RC-250 camera and Sony video printer.

The Cobra III Seal imaging system makes the seal inspection process very simple. A seal is inserted into the Cobra III’s seal receptacle and a photograph of the seal face is taken using the QV-30 digital camera. The camera’s built-in liquid crystal color monitor allows one to view images while photographing the seal’s cable ends, or the monitor can be used to display stored images. Once images are printed using the DP-8000 printer, seal images can then be manually reviewed for physical differences by comparing the two photographs of the seal face. Any differences found may indicate that the seal has been tampered with. The real time display is normally 75% of the full saved image quality, which is 640 x 480 pixels. The four-pass sublimation thermal process provides exceptional image quality.

The image in Figure 2 was taken with a Cobra III camera, saved to the camera’s internal memory, and later transferred through a digital RS-232 port to a Windows 95 based PC. Seal images can be archived in this manner for later verification. All standard image file types are available including JPEG and TIFF. Cataloging of images electronically together with high quality prints both simplify and shorten inspection gathering and analysis.

Figure 2:
Sample Cobra III Image

Typical image gathering time is reduced by the real time display, and quick review of saved images. A maximum of 96 seal images can be stored in the camera’s flash memory. The illumination and optical system was designed to be maintenance-free and easy to manufacture. The depth of field was designed to not be a major factor in the placement of mechanical components building up the optical system. No special alignment, positioning, or optical tools are necessary. Simple assembly and quick verification have made the Cobra III system more accurate and reliable than previous camera systems.

CONCLUSION

Design of the Cobra III camera system was implemented with 3-D modeling tools, which allowed rapid prototyping, accuracy, and simplicity. With a small number of opto-mechanical components in comparison to the automatic verification camera system and ease of use provided by the consumer based QV-30 camera, the overall inspection quality is increased. Real time feedback and quality is key in the process and allows verification to be both quick and accurate. Post-inspection archiving through digital media provides long term storage, retrieval, and electronic inspection capabilities.

In providing better imaging systems, the new digital marketplace has reduced the complexity of Cobra seal imaging to a quick and simple process. The resulting technology reduces inspection time, allowing analysis to be more efficient.