How to convert a 32 bit RGB image to 8 bit gray scale image

[vinodpaul]

Hi, can someone please tell me how to convert a 32 bit RGB image to 8 bit gray scale image. I am using QImage

Thanks

[Zlatomir]

convertToFormat should do the trick.

[vinodpaul]

Hi, thanks for the reply , but that does not work . I tried to convert to QImage::Format_Indexed8, but the grayscale image is not proper.

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Added after 1 30 minutes:

it Worked when I did like this

QImage ImageActionConvert::convertToGray(*pInputImage)
{
 
	if ( pInputImage && !pInputImage->isNull() )
	{
		QImage retImg(pInputImage->width(),pInputImage->height(),QImage::Format_Indexed8);
		QVector<QRgb> table( 256 );
		for( int i = 0; i < 256; ++i )
		{
			table[i] = qRgb(i,i,i);
		}
		retImg.setColorTable(table);
		for(int i =0; i< pInputImage->width();i++)			
		{
			for(int j=0; j< pInputImage->height();j++)
			{
				QRgb value = pInputImage->pixel(i,j);
				retImg.setPixel(i,j,qGray(value));
			}
 
		}
                  return retImg;
          }

QImage ImageActionConvert::convertToGray(*pInputImage)
{
	
	if ( pInputImage && !pInputImage->isNull() )
	{
		QImage retImg(pInputImage->width(),pInputImage->height(),QImage::Format_Indexed8);
		QVector<QRgb> table( 256 );
		for( int i = 0; i < 256; ++i )
		{
			table[i] = qRgb(i,i,i);
		}
		retImg.setColorTable(table);
		for(int i =0; i< pInputImage->width();i++)			
		{
			for(int j=0; j< pInputImage->height();j++)
			{
				QRgb value = pInputImage->pixel(i,j);
				retImg.setPixel(i,j,qGray(value));
			}

		}
                  return retImg;
          }

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