Ways to display QImage

Question

I'm planning to demonstrate some image processing algorithms using OpenCL and Qt.

I know I can display a QImage with QLabel.

Is there any other way? (more efficient, more elegant)

It would be nice, if I could show some "real time" transformation. Is it possible?

Answer 1

you can use;

1. void GLWidget::paintGL() with OpenGL void

   glClear(GL_COLOR_BUFFER_BIT);

   glDrawPixels(img.width(), img.height(), GL_RGBA, GL_UNSIGNED_BYTE, img.bits());

2. void Painter::paintEvent(QPaintEvent* event) with Qt painter

   QPainter painter(this);
   painter.drawImage(0,0,img,0,0,img.width(),img.height());

Answer 2

The one way I know about is to subclass QWidget , override paintEvent and draw QImage using provided QPainter . You may also want to call update() on that widget explicitly if you want to update your image.

Answer 3

You can create an OpenGL context with a QGLWidget and then use OpenCL-OpenGL interchangeability. So, the image is rendered as a texture in OpenGL and computation is done in OpenCL.

Alternatively, have a look at this link http://doc.qt.digia.com/opencl-snapshot/openclgl.html

Answer 4

I've written an example of this using the OpenCL/Qt interop support in Boost.Compute to apply a simple blur filter to a QImage using OpenCL and then display it in a Qt window.

See: https://github.com/kylelutz/compute/blob/master/example/qimage_blur.cpp