Choosing a Camera for your Product

by Maharajan Veerabahu

Introduction

This document would serve as a reference to customers interested in using e-con's e-CAM solution or use its Windows CE/Linux/Windows Mobile* solution to develop various applications such as 1D/2D bar code capture, face recognition, visiting card data capture and Video capture.

Intended Audience

The document is intended for product managers who are interested in integrating camera in to their products and are in need of a complete solution starting with lens assembly, choosing the right sensor for their application and finally provide the Linux/Windows CE/Windows Mobile drivers with appropriate applications.

Choosing the camera and the software

One of the most frequent questions we receive is how do I choose the right camera. By camera we mean the right CMOS sensor with the right lens assembly. Here are the questions the product manager should ask before choosing the camera

Do I require a fixed focus or an auto focus camera?
Does my application need capture at very close distances like 10cm or do I need to capture pictures beyond 20m? How far is my target object from the camera?
What is the resolution I need to support my application?
Do I need an OS to use the camera? If yes, what OS should I use?
Is my environment noisy?
What type of sensor do I need?
What is the ambient lighting condition for my application? What is the performance level expected in low-light condition?
If my application requires video capture, what is the capture rate required at the desired capture resolution?
If my application requires preview, what is the preview resolution required and preview fps (frames per second) required? How much processing is required after capture of each frame?
How can I interface e-CAM with my target board? What are the requirements on power supply, clock and interfacing?

Let's take an example here. If the need of the customer is to capture data from a visiting card then the camera needs to have a fixed focal length and that needs to be less than 10cm. By fixed focal length, the distance between the camera and the object of focus is fixed with 30-40% variance in distance. Also a VGA resolution is good enough for this type of application since the capture area is very small. The application here such as scanning the visiting card and getting the data out of it would involve programming in a high level language and would use many commonly available libraries that run on top of an OS like Windows/Linux. Hence a need of an OS becomes necessary. If the environment is noisy then it is important to choose a sensor that has a high S/N ratio. Finally applications like this need a black and white sensor

Another example would be if the customer wants to capture pictures at variable distances from the camera. This would mean the customer needs an auto focus camera and if the customer needs to capture Video and save it or would want to give an application interface for the end user to develop applications using the camera, it would become mandatory to go for a standard interface like Microsoft Direct show or Video for Linux. Table 1 shows a table that would indicate what type of sensor you should choose based on the application.

Application	Fixed focus	Auto focus	Recommended sensor and software framework
1D/2D bar code	x		VGA type black and white sensor with macro lens assembly. Good
Facial recognition	x	x	Auto focus sensor is a requirement.
IRIS recognition	x		VGA type black and white sensor with macro lens assembly
Still image capture		x	Auto focus 2M pixel or higher. Microsoft Directshow or video for Linux is recommended.
PDA camera		x	Auto focus 2M or higher
Video capture and recording, Video mixing		x	Microsoft DirectShow

e-con's Camera solution

e-con provides complete end-end solution for a customer interested to include camera in its product line. Fig 1 shows the various strengths and skill sets e-con possesses. Here is the brief outline of e-con’s strengths

e-con has got ready made drivers for Windows CE / Windows Mobile and Linux for various camera modules on processors like PXA270, PXA320, AU1250. So if the product that is to be integrated with camera
e-con has camera solution ranging from 0.3 M to 5M pixel.
e-con has a good network of sensor and lens assembly makers. In this aspect, e-con would be able to understand the application requirement and would choose the right sensor and lens assembly for the customer.
e-con has daughter boards for the various camera modules for reference boards like Sirius, Triton starter kit 3 and Triton starter kit 4 . Customers can test their application with various camera modules and once they decide that a particular camera is the right fit for their application then they can go ahead with that. e-con indirectly saves lot of R & D time for the customer in this aspect since tested drivers and daughter modules are available for the various modules.
e-con has got integrated sample applications with its camera drivers like Video streaming, video capture/still capture and has relationships with third parties which can do 1D/2D bar code capture and facial recognition.
E-con exposes the API for its driver package with complete documentation and provides sample applications for easy reference
e-con would act as a one stop shop for the customer regarding the camera.

Figure 1 - e-con's camera strengths

Summary and conclusion

Choosing a camera involves lot of steps like defining the application, choosing the right sensor/module for that application, choosing the right OS and then deciding on the application development. All these involve considerable time and e-con would fit in the role of a partner to the customer with extensive experience in camera development there by reducing the time to market.