Why does rendering on a PC take 10 seconds compared to 0.25 seconds in-camera?

A Owens wrote:

It is written into the raw file at the time the raw file is created. It may assist you if we distinguish the terms "render" and "write". Write is the process of creating the raw file from the sensor data. Render is the process of presenting that data as an image on the camera's LCD. The rendering is ALWAYS done in-camera from the embedded JPEG created when the rest of the raw file is written. When rendering, the camera ONLY uses this embedded jpeg, NONE of the remainder of the raw file. It is quite important to understand that as the implication for it is that the camera's histogram is also from the embedded jpeg and hence rather inaccurate. One can of course get close to the raw histogram using uniWB but that is another topic.

This is why the camera renders so quickly. The WRITE process on the other hand, takes rather a lot longer. You can see how long it takes by shooting in live view. The silly damn D800 does not internally buffer this process in live view and it seems to take forever, especially with a slow card - drives me mad!

--
Alistair Owens
http://www.alistairowensphotography.com