Camera Raw Adds Noise to My Image [duplicate]

Question

I originally thought that saving my images as TIFs from PS was degrading my image quality until I realized that my RAW files were coming into PS that way.

So I looked into it further and found that my CR2 files (from my Canon 7D Mk II) didn't look as good once brought into Camera Raw, which I'm using with PS CS6.

So once in Camera Raw the image had more noise than the RAW image.

Is there something I'm doing wrong (can't imagine because I'm simply opening the file and not making any adjustments), or is there a different way that I can get a clean RAW file into PS for editing?

Thanks in advance for your feedback!

Anthony

Answer 1

When you take a photo with a modern camera there is an amount of processing that will occur on the camera. This can include noise reduction, sharpening, exposure adjustments etc. The adjustments are typically present in jpeg/tiff output.

RAW format on the other hand gives you the output of the camera without this in-camera processing, hence "raw". It is highly likely that what you are seeing is not a problem in the RAW output, but rather the absence of the in-camera processing that you are used to getting with the jpeg.

The solution with RAW is to post process the image yourself, for which there are many good tools such as Adobe Lightroom. The advantage is that you can make decisions about what processing is needed for the specific image, whereas the camera can only approximate this using fixed settings or pre-programmed rules.

Answer 2

It sounds like when you are viewing your "raw image" before opening it in Adobe Camera Raw you are actually looking at the JPEG preview that is generated in-camera and attached to the raw file. Whatever settings are set in camera at the time the image is captured are applied to the raw data to produce the preview image. Along with color temperature/white balance, contrast, saturation, etc. this normally includes noise reduction as well.

The reason this is done is because you can't really view the raw data itself as an image the way we expect an image to appear. Raw files contain brightness values for each sensel (pixel well) on the sensor. The relative brightness value of the signal from each sensel is affected by whether that sensel has a blue, green, or red filter in front of it. Even if we did try to look at the monochromatic luminance values from each sensel, our camera's lcd screens and computer screens aren't capable of displaying 12-bit to 14-bit gradations in brightness. The signal from the sensor also needs to be converted from linear response values to more logarithmic values on a light curve shaped to match our eyes' response to various brightness levels.

The jpeg preview is what you see when you look at a "raw image" on the LCD screen on the back of your camera. Depending on the settings of whatever application you use to view a raw file the jpeg preview can also be what you are seeing when you look at it on your computer, too.

When you open the actual raw data in Adobe Camera Raw the default settings in ACR are used to interpret the image data. This may have more or less noise reduction applied than was used to create the jpeg preview. It sounds like in your case there is less. If you want to apply more noise reduction then you'll have to use the controls in ACR to increase the amount of noise reduction. There are two basic type of noise: luminance and chrominance. Luminance noise is what makes images look grainy. Chrominance noise is what make colors look 'speckly.'

Changing other settings can also increase the amount of noise you see. Increasing saturation also increases chrominance noise. Boosting exposure/brightness increases noise because the noise is amplified along with the signal. Sharpening an image will make noise in the image more noticeable.

Answer 3

I don't think you understand RAW. That format contains exactly the recorded signal in each pixel. It may well be that your software import tools are doing something stupid like, say, expanding 12-bit values to 16-bit with random cruft thrown into the fake bits. More likely is that you're accustomed to seeing the results of various smoothing algos which generate pixel values based on neighbors as well as some on-the-fly statistics of eac pixel's fundamental readout quality.