Is it possible to render framebuffer from another entity's camera without displaying it on screen?

I'm trying to make a camera peripheral block for computercraft (1.18.2 forge), but stuck at the start now

I want it to create a virtual camera entity, then return what it sees as imageBuffer so that it can be displayed by monitor from Tom's peripheral mod.

So first I tried using a specific entity as the carrier of camera.

I tried save the original mainRenderTarget, then create a new RenderTarget(or framebuffer) when RenderHandEvent fired, then use setCameraEntity to move the camera to that specific entity, render what it sees and write it into the new RenderTarget.

I did get the view from that entity as bufferedImage, then save it as a png file. 

But in game, both entity's camera view and player's camera view were displayed. Is it possible to render a entity's camera view without displaying it on screen?