Monitoring on pixel level

This is a discussion on Monitoring on pixel level within the Windows Programming forums, part of the Platform Specific Boards category; I would like to monitor several windows, in each window i would like to monitor several pixels continuously. What is ...

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    Monitoring on pixel level

    I would like to monitor several windows, in each window i would like to monitor several pixels continuously. What is the best way of doing this?

    Is it possible to monitor a windows pixel even if it is not in focus on the screen or even if it is minimizes to system tray?

    Using the GetDc and then GetPixel is the only thing i have used before but i feel there must be a faster and better way to solve this problem?

    (im not an english native speaker)

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    No one?

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    I think we're all asking: "Why on earth would he want to do that?"

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    Hehe ok, i think this is the only way to monitor this program. It is a program that recive an image from a camera over the internet and i would like to watch a few specific pixels in the image for when they cange color so that i know an event have happened. Does it make more sens now?

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    and the hat of wrongness Salem's Avatar
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    An image library like opencv, and some search terms like "motion detection" would be a good start.
    VideoSurveillance - OpenCV Wiki
    Tips: Motion Detection using OpenCV
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    The thing is that i do not need to make this that advanced. I do not need to detect movment or anything, all i want to do is look at a few x:y cordinates in the image and monitor what colors they have. This i can do with the GetDc and GetPixel but what i am wondering is if there is a way to monitor a pixel in a window without having to catch and release the DC every time i want to get the color for that pixel?

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    When the camera sends you a new image there should be some event / msg to show there is a new image to display on the screen.

    You could check the raw image data (rather than the HBITMAP data displayed in the HDC) when you process this msg.

    I did similar to monitor the lights on the back of servers (to check for warning lights turning from green to red).
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    When i use spy++ to see what messages is in the process i cant find any relevant. Sure i get the standard ones when moving the moue but other than that it is silent. How is the program made when it dont show any msg for event?

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    Before the window gets painted to the screen is it not saved in the graphics cards memory? Can i not acces that memory to read the pixel? Is this something i can use opengl for?

  10. #10
    and the hat of wrongness Salem's Avatar
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    Why not replace the camera application with your own, and read the images directly?
    If you dance barefoot on the broken glass of undefined behaviour, you've got to expect the occasional cut.
    If at first you don't succeed, try writing your phone number on the exam paper.
    I support http://www.ukip.org/ as the first necessary step to a free Europe.

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