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Electronics Forum / Electronics / October 2003Superimposed video crosshairs
Does anyone know a circuit which could generate crosshairs which can be superimposed over an existing video feed such as from a CCD camera? I'd like to make some simple crosshair patterns like a horiz+vert line, horiz line, vert line, frame, corners, etc. A microcontroller of somesort could generate the patterns but I'm not sure how to overlay the crosshairs without disrupting the original video feed. >Does anyone know a circuit which could generate crosshairs which can >be superimposed over an existing video feed such as from a CCD camera? [quoted text clipped - 3 lines] >of somesort could generate the patterns but I'm not sure how to >overlay the crosshairs without disrupting the original video feed. Did exactly that (and rather more) somewhere over 20 years ago :) Used an NEC video controller with some dynamic ram and wrote the digital data to that then synced and mixed it with the incoming video, The circuits and software are long gone though I'm afraid. Surely a net search for "video overlay" will turn up lots of clues? Mike Harding > Does anyone know a circuit which could generate crosshairs which can > be superimposed over an existing video feed such as from a CCD camera? [quoted text clipped - 3 lines] > of somesort could generate the patterns but I'm not sure how to > overlay the crosshairs without disrupting the original video feed. You could use the (nearly obsolete but still available) STV5730A OSD chip. You can program custom characters to create various lines or whatever. A two chip solution with say a PIC micro tied onto it. Alternatively you can use one of the various modules around that have this chip on it already and are easy to program with the serial port. Dontronics have (or used to have) a SimStick version available. Regards Dave :) > > Does anyone know a circuit which could generate crosshairs which can > > be superimposed over an existing video feed such as from a CCD camera? [quoted text clipped - 13 lines] > Regards > Dave :) still have Dave, http://www.dontronics.com/dt108.html may be of some help. Don...  SignatureDon McKenzie E-mail: http://www.dontronics.com/e-mail.html Home Page: http://www.dontronics.com USB to RS232 Converter that works http://www.dontronics.com/usb_232.html The World's Largest Range of Atmel/AVR & PICmicro Hardware and Software > Does anyone know a circuit which could generate crosshairs which can > be superimposed over an existing video feed such as from a CCD camera? [quoted text clipped - 3 lines] > of somesort could generate the patterns but I'm not sure how to > overlay the crosshairs without disrupting the original video feed. I'm looking for more or less the same, for a small project too. I just recently found this... http://www.decadenet.com/bob3/bob3.html haven't used it but it looks like it'll do what you want. It has various 'line characters' in it's extended RAM character sets let us know what you end up doing. >> Does anyone know a circuit which could generate crosshairs which can >> be superimposed over an existing video feed such as from a CCD camera? [quoted text clipped - 15 lines] > >let us know what you end up doing. I'd love to know what OSD chip they are using... Looks as though they have rubbed off the numbers on the chip. They may have gone with a custom chip in this third generation device, to prevent problems with the discontinuation of almost all the OSD chips out there. Dave :) --------------------------- (remove the "_" from my email address to reply) > to prevent problems with the discontinuation of almost all the OSD > chips out there. i wonder why they're all discontinued... one would have thought OSD IC's are pretty useful/popular thing with electronics hobbyist. >> to prevent problems with the discontinuation >> of almost all the OSD chips out there. > i wonder why they're all discontinued... one would have thought > OSD IC's are pretty useful/popular thing with electronics hobbyist. Presumably there arent enough of those to provide a viable market. >>i wonder why they're all discontinued... one would have thought >>OSD IC's are pretty useful/popular thing with electronics hobbyist. > Presumably there arent enough of those to provide a viable market. This was brought up on another group, my theory was that since the bulk of modern video equipment out there generates the video digitally, OSD text is generated using the processors that are already there. The separate OSD devices have effectively become obselete because it's easier to create the text at the same time as the video, rather than do it later in the analogue realm. The fact that hobbyists have lost out because of this is "just too bad". Besides, couldn't a pic and a sync separator do it? Albeit with a few limitations? SignatureLinux Registered User # 302622 <http://counter.li.org> >>> i wonder why they're all discontinued... one would have thought >>> OSD IC's are pretty useful/popular thing with electronics hobbyist. >> Presumably there arent enough of those to provide a viable market. > This was brought up on another group, my theory was that since the > bulk of modern video equipment out there generates the video digitally, > OSD text is generated using the processors that are already there. > The separate OSD devices have effectively become obselete > because it's easier to create the text at the same time as the > video, rather than do it later in the analogue realm. Yep, thats another way of spelling out the lack of a viable market now. > The fact that hobbyists have lost out because of this is "just too bad". Yep, and if there was a viable market, presumably someone could just buy up whats still around and flog them to that market. > Besides, couldn't a pic and a sync separator do it? Albeit with a few limitations? Yeah, that was my reaction. Havent actually tried it tho. |
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