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Why this program doesn't work?

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  • H Offline
    H Offline
    hor_313
    wrote on last edited by
    #1

    Hi

    This code runs with rgb colors but when i change it to cmyk , it doesn't work . why?

    @ QImage image=QImage("/home/mohammad/1.jpg").scaled(ui->spinBox->value(),ui->spinBox_2->value());
    int i=0 ;int j =0;

    for(j=0 ; j<image.width();j++)
    { for(i=0;i<image.height();i++)
        {
            QColor color=QColor::fromCmyk(image.pixel(i,j));
    
    ui->plainTextEdit->appendPlainText(QString("cyan is : ") + QString::number(color.cyan())
                                       + QString("magenta is: ") + QString::number(color.magenta())
                                       + QString("yellow is:") + QString::number(color.yellow())
                                       + QString("black is") +QString::number(color.black()));
    

    }
    }@

    this is the error : no matching function for call to "QColor::fromCmyk(Qrgb);

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    • T Offline
      T Offline
      tobias.hunger
      wrote on last edited by
      #2

      Why would you expect that a method called "fromCymk" will accept a RGB value? Just looking at the name I would expect that method to require a CYMK value.

      Try "fromRgb" to turn the Rgb value into a QColor.

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      • H Offline
        H Offline
        hor_313
        wrote on last edited by
        #3

        [quote author="Tobias Hunger" date="1367692122"]Why would you expect that a method called "fromCymk" will accept a RGB value? Just looking at the name I would expect that method to require a CYMK value.

        Try "fromRgb" to turn the Rgb value into a QColor.[/quote]

        cause I want to rich cmyk values of an image!
        Is it possible? how?

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        • SGaistS Offline
          SGaistS Offline
          SGaist
          Lifetime Qt Champion
          wrote on last edited by
          #4

          You have to do a color space conversion from RGB to CMYK, QColor has functions for that

          Interested in AI ? www.idiap.ch
          Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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          • H Offline
            H Offline
            hor_313
            wrote on last edited by
            #5

            I solved it by adding toCmyk() function after this line :

            @QColor color=QColor::fromRgb(image.pixel(i,j)).toCmyk();@

            and so changing fromCmyk to fromRgb

            and the program is working , but i am not sure the returns value are true ?!

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            • SGaistS Offline
              SGaistS Offline
              SGaist
              Lifetime Qt Champion
              wrote on last edited by
              #6

              What do you mean by true ?

              Interested in AI ? www.idiap.ch
              Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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              • K Offline
                K Offline
                KA51O
                wrote on last edited by
                #7

                i would assume he meant true = correct (not true as a boolean value).

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                • SGaistS Offline
                  SGaistS Offline
                  SGaist
                  Lifetime Qt Champion
                  wrote on last edited by
                  #8

                  I would in the first place but there is also the notion of "true color", that's why I asked

                  Interested in AI ? www.idiap.ch
                  Please read the Qt Code of Conduct - https://forum.qt.io/topic/113070/qt-code-of-conduct

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