How to get colored QImage

[Nadja]

Hey, I want to open a .png using QFileDialog. Works fine for .txt & .png! Unfortunately the Imige is only shown in gray. Although reading the Docu and some examples i cant solve my problem. Try to build a color Table in a few ways but it doesn`t works. Using a QLabel to display the Image. Could anybody help? Sorry for my English. Isn`t the best. Nadja

void MyClass::open()
{
	QString filename = QFileDialog::getOpenFileName(this,tr("Load File"),"",tr("Text Files (*.txt);;Images (*.png *.jpg)"));
 
	if (filename != "") {
	  /*QFile file(filename);
		if (!file.open(QIODevice::ReadOnly)) {
			QMessageBox::critical(this, tr("Error"), tr("Could not open file"));
			return;}
 
		QString contents = file.readAll().constData();
		ui.Textfeld  -> setPlainText(contents);
		file.close();}*/
 
	QImage image(filename);
	image = image.convertToFormat(QImage::Format_Indexed8); //shows the image in gray
	/*image = QImage(600, 453, QImage::Format_Indexed8);*/  // shows black and white stripes (why?)
 
	QVector<QRgb>  table(256);
	for(int i = 0; i < table.size(); i++)
	{table[i] = qRgb ( i,i,i );}
	image.setColorTable(table);
 
	/*QRgb i;
	for ( int i=0; i<256; i++ )  //build color Table
	image.setColor(i,qRgb(i,i,i));*/
 
              //image.fill(qRgb(255,255,255));
	//image.setColor( 19, qRgb(255,255,0) );	
	//(image.scanLine(y) + x) = 19;
	/*QPixmap pixmap;
	pixmap = pixmap.fromImage(image);*/
 
	ui.Display->setPixmap(QPixmap::fromImage(image));}
}

void MyClass::open()
{
	QString filename = QFileDialog::getOpenFileName(this,tr("Load File"),"",tr("Text Files (*.txt);;Images (*.png *.jpg)"));

	if (filename != "") {
	  /*QFile file(filename);
		if (!file.open(QIODevice::ReadOnly)) {
			QMessageBox::critical(this, tr("Error"), tr("Could not open file"));
			return;}

		QString contents = file.readAll().constData();
		ui.Textfeld  -> setPlainText(contents);
		file.close();}*/

	QImage image(filename);
	image = image.convertToFormat(QImage::Format_Indexed8); //shows the image in gray
	/*image = QImage(600, 453, QImage::Format_Indexed8);*/  // shows black and white stripes (why?)

	QVector<QRgb>  table(256);
	for(int i = 0; i < table.size(); i++)
	{table[i] = qRgb ( i,i,i );}
	image.setColorTable(table);

	/*QRgb i;
	for ( int i=0; i<256; i++ )  //build color Table
	image.setColor(i,qRgb(i,i,i));*/
	
              //image.fill(qRgb(255,255,255));
	//image.setColor( 19, qRgb(255,255,0) );	
	//(image.scanLine(y) + x) = 19;
	/*QPixmap pixmap;
	pixmap = pixmap.fromImage(image);*/

	ui.Display->setPixmap(QPixmap::fromImage(image));}
}

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[Lykurg]

qRgb ( i,i,i ) will always be gray!

[mvuori]

And of course the colour map needs to be created _before_ conversion and passed as an argument to the conversion. How else would Qt know to what index to map each RGB pixel using a closest match principle.

So, you need to get a ready-made colour map data from somewhere...

[Nadja]

Okay.....you`re right.....but how to do it otherwise.....do i have to build a loop for each Rgb value......means instead of i,i,i, to use i for red, j for green and k for blue??? Is it right to use QRgb? Did I have to use a Vector or does QT have another possibility???
And why do I get the black and white Stripes when I use: image = QImage(600, 453, QImage::Format_Indexed8???

Would be very nice if someone can help a little bit more. I`m not a Guru but it`ll be nice to get one in a few years :-p ....greetz Nadja