How to design a custom videoOutput?

The videoOutput I mean is     Rectangle {         width: 320         height: 240               Camera{             id: camera         }               VideoOutput {             id: videoOutput                   anchors.fill: parent             source: camera         }                   GammaAdjust {             id: gammaAdjust                   anchors.fill: videoOutput             source: videoOutput             gamma: 0.5         }     } How could design the videoOutput by myself? Maybe this is the fastest and easiest way to save the image after postprocessing,thanks