Howard, 1. If you want to do color measurements, you need a color camera. You would need double the resolution of the screen (or more) to examine individual pixels. It sounds like you may need in the neighborhood of 1300x1000 resolution. You will need a little more resolution to handle the different sizes of screens and variations in position of the screen. I strongly suggest a camera that converts to digital onboard instead of sending an analog signal. You also need to select the appropriate lens to give you the best field of view. Graftek Imaging (800) 441-2118 is a good place to get the camera, lens, etc. They can help you figure out what you need.
2. I prefer firewire for its simplicity. The actual connection to your computer will depend on the camera. You just need to get the board that matches your camera type. 3. This could possibly be done using Vision Builder for Automated Inspection. It wouldn't take long to get a prototype working. I'm not sure if the final version would work in VBAI or if it would need to be converted over to LV. 4. No, you don't need to upgrade. You might be missing a few new tools in the old version of LV, but the newest version of Vision will work with older versions of LV. 5. Good question. If the backlight isn't strong enough, you would need additional lighting. If outside light is on the same order of magnitude as the backlight, you will need to shield the outside light. Lighting is a little bit of trial and error. 6. With a high resolution color camera, you could probably do most of this. If you go with a less expensive B&W camera, you probably won't be able to do this. 7. Fixturing really depends on the system. You don't want the camera to move relative to the screen so that the focus and field of view are consistent. It also depends on what lighting is used. 8. It really depends what the test is. If you are just adding another of the same, such as OCR of certain regions, it would be hours. If you are developing a new test to detect missing pixels, it would take much longer. The most critical thing in vision applications is getting a good image for analysis. Camera, lens, lighting, field of view, depth of field, etc. all play a part in this. Once you have a good image the analysis can be fairly straightforward. Also make sure you have enough resolution for the OCR to work. The width of each line in the characters should be several pixels in your image for the best results. You will need to do a lot of prototyping to make sure this works properly. Bruce ------------------------------------------ Bruce Ammons Ammons Engineering www.ammonsengineering.com (810) 687-4288 Phone (810) 687-6202 Fax -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED] On Behalf Of Spec, Howard Sent: Thursday, June 03, 2004 2:21 PM To: Info LabVIEW Mailing List Subject: [W] Machine Vision question Hi, I have been asked to look into the feasibility of using Vision S/W and H/W inorder to automate verification testing of avionics boxes with Active Matrix or LCD displays. The display size is typically 4X5 inches. I think the requirement would be simple - take a snapshot of the display and get the text/numeric data from specific fields. This would be repeated for a number of different screens. I might have to verify that the data field is in the right location on the screen as well. Most of the box displays are monochrome active matrix Electro luminescent, but newer products are using color LCD displays. The resolution of the displays range from 320X192 up to 640 X480. I am a Labview programmer with 8 years of experience, but have no experience with machine vision. I would really appreciate it if anyone out there that has done something similar to this could provide answers to the following questions: 1. What type of camera would be required for this type of app, with what resolution? Do I really need a video camera or could I just use a single shot digital camera. 2. What NI board would I need. 3. How long would it take an experienced Labview programmer to come up to speed with the Vision Development module and OCR inorder to be able to produce a simple demo (grab a frame, read data from two or three fields)? 4. I am using Labview 6.0.2 - will I have to upgrade to 7.1 inorder to use the latest Vision Development Module? 5. What will the lighting issues be - since the display is back lit, would I even need additional light? Would I have to block outside light? 6. Would I also be able to perform optical testing of Luminance, chromaticity, legibility and pixel defects (not a requirement but for future growth ;) 7. What is recommended for fixturing. 8. Once up to speed with the vision tools, how quickly could a test for a new screen be done - hours, days?? I really look forward to the challenge of learning vision acquisition techniques, but I am a bit worried that I may have bitten off a little more than I can chew ;) Any help with this would be greatly appreciated, Howard Spec CMC Electronics Ottawa, Canada
