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  • uCam-III unknown JPG format

    I'm trying to figure out what type of JPG the camera is sending back, because I need to decode the JPG and generate a thumbnail from it.
    Normally, you would have JPG files starting with FFD8FFE0 or FFD8FFE1. However, mine all start with FFD8FFDB for some reason.

    This image was created by using the INITIAL command with JPG(640x480), SNAPSHOT command with JPG, and finally GET PICTURE command to get the snapshot.

    I suppose there are several questions here:
    1. What type of JPG is this process creating?
    2. Is there a way to generate a thumbnail directly with the uCamIII?
    3. Is what I am doing the proper way to get an image from uCamIII?

  • #2
    Hello,

    Have you tried to use the uCAM Demo Application? Using the application, you can always check its JPG image.

    Normally, you would have JPG files starting with FFD8FFE0 or FFD8FFE1. However, mine all start with FFD8FFDB for some reason.
    Referring to WiKi's link on JPEG - the SOI is FF D8 and is mandatory on any JPEG file extensions.
    However, the next byte (APP markers) does not always need to be FF E0 or FF E1.

    There is a discussion on this topic in some forums, you might want to check for it.
    https://stackoverflow.com/questions/...or-app1-marker

    I suppose there are several questions here:
    1. What type of JPG is this process creating?
    2. Is there a way to generate a thumbnail directly with the uCamIII?
    3. Is what I am doing the proper way to get an image from uCamIII?
    1.) Try to capture an image using the uCAM Demo Application and save the image using JPG configuration.
    Check the image data using Hex Edit Neo.
    2.) You need to translate the data that you receive from the uCAM, and the uCAM Demo Application does this for you.

    This image was created by using the INITIAL command with JPG(640x480), SNAPSHOT command with JPG, and finally GET PICTURE command to get the snapshot.
    3.) Yes, you should be able to get an image by following that sequence (don't forget to add the sync)

    Best Regards,
    Kevin
    Last edited by John Kevin; 31st July 2019, 04:41 PM.

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    • #3
      Hello again,

      Yes, I have used the Demo Application to test out the uCamIII, but I cannot use it in the final product.
      Because we plan to mount these cameras on Cubesats sent to space.

      What I am wondering is if the uCam can give me both a thumbnail and a picture.
      Because...When I do SNAPSHOT with JPG, it takes a JPG picture and stores it in the camera.
      Then, when I do GET PICTURE, the uCamIII sends me bytes representing the JPG picture.

      I know this is probably unlikely, but is there a command I can send for the uCamIII to send me bytes representing the thumbnail, or reduced version of the picture?

      Thanks,
      Haomin

      Comment


      • #4
        Hi Haomin,

        Thank you for your reply.
        Using the Demo Application, we can say that the uCAM-III that you received is good and working properly.

        I know this is probably unlikely, but is there a command I can send for the uCamIII to send me bytes representing the thumbnail, or reduced version of the picture?
        AFAIK, there is no command for the thumbnail that you have mentioned.
        The size of each picture is set during initialization and processing the bytes from the uCAM is the only way to produce the JPEG file.

        I hope this helps.
        Best Regards,
        Kevin

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