See also：
I need to dynamically create a camera and take a screenshot using OutputRenderTarget, However, when the scene has a Default Rendering pipeline, the color output is in linear space
This is totally expected as it needs to be in linear space (it is an intermediate step of the pipeline) and not in gamma space.
But what should I do if the texture image I want to output matches the effect displayed on the screen?
Babylon.js docs should help
CreateScreenshotUsingRenderTarget cannot capture the layer used for the background image, so I chose camera.outrenderTarget, which is also the method I found in the forum
So you need to disable/enable the post processes on demand depending on the camera https://playground.babylonjs.com/#VC3WC7#11