How much does in-camera image processing affect noise on Canon DSLRs?

Question

I've found out that some of photos take with my 5D MkII have more shadow noise than I like. I know there are some obvious settings that affect this, such as ISO a noise reduction settings. But there are some other image processing functions that probably raise noisiness of the images.

This was shot at ISO 400, and kind of underexposed. Other settings I believe might be relevant:

• High ISO NR: low
• Highlight tone priority: disabled
• Auto ligting optimizer: low
• Peripheral illumination correction: enabled

Now, is there some kind of tuning of all this I could do to achieve pictures with which I can postprocess a bit without getting noisy results, or should I consider this normal and focus on taking pictures rather than thinking about chroma noise?

Answer 1

HTP will increase noise as it underexposes the image in order to avoid possibly clipping the highlights. Noise reduction will obviously reduce noise, but at the expense of fine details.

All other in camera processing may reveal noise, but not create it. If you are concerned about noise then I would highly recommend shooting Raw and taking full control over the processing and noise reduction applied. This is especially true if you intend to postprocess!

How you shoot will influence noise far more than in camera settings. Basically you want to get as much light down the lens as possible. Don't shy away from using a higher ISO if you cant get any more light as this will help overcome read noise in the shadows. Exposing to the right will help reduce shadow noise, possibly at the expense of highlight detail and colour fidelity - everything is a trade off I'm afraid!

Answer 2

Shoot raw (plus jpg if you prefer) and don't underexpose then try to compensate afterwards! When you process your raw file on your computer you can use Noise Ninja or similar, which is much more sophisticated than anything the camera can manage in the time allowed. An additional post-processing tip is to make a couple of layers with different amounts of noise reduction and use a layer mask to expose the more-agressively-reduced version in the troublesome areas. This is because all noise reduction has a tendency to reduce fine details, which is fine in flat areas of colour but can make e.g. hair look weird.

Answer 3

shoot RAW but be aware that the 5Dmk2 does not produce the cleaneast shadow tones, especially when under exposed. Also HTP in my opinion is a waste of time and makes the noise worse for very little gain in recoverable highlights. I use mine a lot for landscape and its fantastic for that but when i shoot portraits i am increasing becomming dissapointed with the amount of noise in shadows and mid tones when they are brightened up in RAW regardless of the programs used. NR can make a difference but it can kill some fine detail too.