Why this program doesn't work?

hor_313

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);

tobias.hunger

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.

hor_313

[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?

SGaist

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

hor_313

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 ?!

SGaist

What do you mean by true ?

KA51O

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

SGaist

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