glTexSubImage2D(GL_TEXTURE_2D,0,0,0,widthGL,heightGL,
                GL_LUMINANCE,GL_UNSIGNED_BYTE,noise);
//computation
QImage mySurface(noise,widthGL,heightGL,QImage::Format_Indexed8);
mySurface.save("test.bmp","BMP");

static unsigned char* mbuffer = new unsigned char[3*widthGL*heightGL];
for (int i = 0,bpos=0;i<widthGL*heightGL;i++)
{
mbuffer[bpos++]=noise[i];
mbuffer[bpos++]=noise[i];
mbuffer[bpos++]=noise[i];
}
QImage mySurface(mbuffer,widthGL,heightGL,QImage::Format_RGB888);

glTexSubImage2D(GL_TEXTURE_2D,0,0,0,widthGL,heightGL,GL_LUMINANCE,GL_UNSIGNED_BYTE,noise);
//computation
QVector<QRgb> colorTable(256); //our grayscale palette
QImage mySurface(noise,widthGL,heightGL,QImage::Format_Indexed8);
for (int i = 0; i < 256; ++i)
     colorTable[i] = qRgb(i, i, i); //build palette
mySurface.setColorCount(256);
mySurface.setColorTable(colorTable);
mySurface.save("test.bmp","BMP");