The plan is that my program gets a stream of pictures, at least 1 per second (three would be better).
The program does nothing until it detects some movement. After that it waits for silence again, takes the actual picture, corrects the image orientation and cuts out the irrelevant parts (borders). The next step is to find the page number, cut it out and gives it to an OCR program (for example Tesseract). The OCR recognizes the page number and than it can be spoken out by a screen reader. This has the advantage, that the blind user can skip through a book and easily can find a certain page. But for that I need the picture stream.
So I imagine that the camera is triggered by a script and takes the pictures and my program can use these pictures nearly at the same time. So I would connect the camera to my PC via USB, start the script on the cam and then pick up the newly arriving pictures from the mass storage of the cam (which is also shown in the windows explorer). Would this work?
No modern Canon P&S act as USB mass storage. They use PTP, which is a much more limited protocol, and cannot be accessed with regular file system functions.An alternative would be to use eye-fi http://www.eye.fi/ to retrieve the pictures.
Wouldn't it be far far easier to just dog-ear Page #1 and have them count the pages? (Or for skipping purposes, dog-ear every 10th page.) They could probably do it much faster that way and with more assurance than depending on some hit 'n miss OCR. Or braille emboss the page numbers?
Most CHDK cameras will not be able to accomplish this in photo mode. Few do much better than 1 fps (there are some exceptions, e.g. CMOS cameras, and cameras that have a reduced resolution "high iso" mode).
For an extremely good tethered shooting software for older Canon cameras, see Cam4You RemoteThis has automated off-loading of photos and all the bells and whistles you'd need if you are going to shoot tethered anyway. It's the best tethered-shooting software that's ever been made. Best of all, the author now made it freeware. It's only a matter of finding older cameras supported by that software. Making the costs of your project minimal if you hunt on ebay for a good deal.
If I interpret the rest of your posts right, I see two possible solutions:1. I connect the digital camera via USB to my PC and use the PTP protocol to trigger the take photo script on the cam and after that receive the taken picture and save it on a folder on the HDD from where I can load it into my program.2. I construct the USB remote cable (see wiki article) and use that to take the picture. To get the taken picture I would use the eye-fi card.I prefer method 1 cause if it works it's much easyer to build and cheeper. Could you help me a bit further with this PTP protocol? Very helpful would be a simple list of steps, starting with a new bought Canon cam.
Quote from: NewbieToobie on 01 / May / 2011, 16:38:11For an extremely good tethered shooting software for older Canon cameras, see Cam4You RemoteThis has automated off-loading of photos and all the bells and whistles you'd need if you are going to shoot tethered anyway. It's the best tethered-shooting software that's ever been made. Best of all, the author now made it freeware. It's only a matter of finding older cameras supported by that software. Making the costs of your project minimal if you hunt on ebay for a good deal.This sounds good but the supported camera models are a bit too old for my purpose. The taken pictures should be better then these from the Logitech C910 web cam which I use at the moment.
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