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Image processing

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  • A Offline
    A Offline
    AxZaHeCa
    wrote on last edited by
    #1

    Hi everybody, I want to use the QImage class as opencv form to access the pixels and manipulate it as the function image.at<uchar>(i, j) because opencv android is useless in QT android, someone knows the way to access the pixels properly???

    Pablo J. RoginaP 1 Reply Last reply
    0
    • mrjjM Offline
      mrjjM Offline
      mrjj
      Lifetime Qt Champion
      wrote on last edited by mrjj
      #2

      Hi and welcome to the forums
      You mean something like
      https://doc.qt.io/qt-5/qimage.html#bits
      ?

      A 1 Reply Last reply
      1
      • A AxZaHeCa

        Hi everybody, I want to use the QImage class as opencv form to access the pixels and manipulate it as the function image.at<uchar>(i, j) because opencv android is useless in QT android, someone knows the way to access the pixels properly???

        Pablo J. RoginaP Offline
        Pablo J. RoginaP Offline
        Pablo J. Rogina
        wrote on last edited by
        #3

        @AxZaHeCa said in Image processing:

        opencv android is useless in QT android,

        Are you sure? I'm able to run a sample app on Android with Qt 5.12 + OpenCV 4.0 for Android pre-built with no issues.

        You may want to look at this blog post just in case.

        Upvote the answer(s) that helped you solve the issue
        Use "Topic Tools" button to mark your post as Solved
        Add screenshots via postimage.org
        Don't ask support requests via chat/PM. Please use the forum so others can benefit from the solution in the future

        A 1 Reply Last reply
        2
        • mrjjM mrjj

          Hi and welcome to the forums
          You mean something like
          https://doc.qt.io/qt-5/qimage.html#bits
          ?

          A Offline
          A Offline
          AxZaHeCa
          wrote on last edited by
          #4

          @mrjj how can you use this function?? because i saw that returns a pointer to the first pixel data but i don't see how can you get the pixel value in the (i,j) position

          mrjjM 1 Reply Last reply
          0
          • A AxZaHeCa

            @mrjj how can you use this function?? because i saw that returns a pointer to the first pixel data but i don't see how can you get the pixel value in the (i,j) position

            mrjjM Offline
            mrjjM Offline
            mrjj
            Lifetime Qt Champion
            wrote on last edited by
            #5

            @AxZaHeCa
            Hi
            well its actually ScanLine you will use as seen here
            https://forum.qt.io/topic/73504/qimage-read-pixels-and-copy-them-with-scanline-method
            this might also be of interrest
            https://doc.qt.io/qt-5/qimage.html#pixel-manipulation

            A 1 Reply Last reply
            1
            • mrjjM mrjj

              @AxZaHeCa
              Hi
              well its actually ScanLine you will use as seen here
              https://forum.qt.io/topic/73504/qimage-read-pixels-and-copy-them-with-scanline-method
              this might also be of interrest
              https://doc.qt.io/qt-5/qimage.html#pixel-manipulation

              A Offline
              A Offline
              AxZaHeCa
              wrote on last edited by
              #6

              @mrjj ok ,I don't know if Qrgb is a qreal value, because want to create a histogram from a grayscale image and create a binary image using Otsu method

              mrjjM 1 Reply Last reply
              0
              • Pablo J. RoginaP Pablo J. Rogina

                @AxZaHeCa said in Image processing:

                opencv android is useless in QT android,

                Are you sure? I'm able to run a sample app on Android with Qt 5.12 + OpenCV 4.0 for Android pre-built with no issues.

                You may want to look at this blog post just in case.

                A Offline
                A Offline
                AxZaHeCa
                wrote on last edited by
                #7

                @Pablo-J.-Rogina I had problems with the lopencv_core.a it show that this static library has some extra characters

                1 Reply Last reply
                0
                • A AxZaHeCa

                  @mrjj ok ,I don't know if Qrgb is a qreal value, because want to create a histogram from a grayscale image and create a binary image using Otsu method

                  mrjjM Offline
                  mrjjM Offline
                  mrjj
                  Lifetime Qt Champion
                  wrote on last edited by
                  #8

                  @AxZaHeCa
                  well docs
                  says
                  typedef QRgb
                  An ARGB quadruplet on the format #AARRGGBB, equivalent to an unsigned int.

                  1 Reply Last reply
                  1

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