Question about noise and RAW

I shot some pictures this weekend and noticed that with my
Rebel XT while shooting in RAW, the pictures were noisy/yat 100% crop. Thumbnails and previews look fine but when I click on the image in DPP, I can see the noise in the form of rainbow colored pixels. Of course it is more prevelant at ISO 1600, but even shots at ISO 200 I can see noise at the 67% crop in DPP.

Is this because RAW has no processing and noise reduction is done through the DIGIC II chip? Or is there something wrong with my CMOS sensor? Or is it something else all together? Appreciate your help.

Probably would help if you can post a 100% crop pic of what the noise looks like.

Greg

00silvergt wrote in post #3491754
Is this because RAW has no processing and noise reduction is done through the DIGIC II chip? Or is there something wrong with my CMOS sensor? Or is it something else all together? Appreciate your help.

It depends a lot on how well you expose the shot in the 1st place. Even at ISO100, if the shot is underexposed, you'll see some noise.

I am not aware of any noise reduction done on jpeg in the camera. I know there is a custom function to apply noise reduction for long exposure but that's for unique occasion. The jpeg version of a photo (straight from camera) has the same amount of noise as its raw counterpart if not more, depending on the Sharpening parameter in the camera that you set. Sharpening accentuates noise. Not sure about DPP (i guess it's the same) when viewing a photo via RawShooterEssential or ACR, I turn off the preview if I want to see the image without any preset editing. Hope that makes sense.

Will do when I get home. However, they will be .CR2 files, how do I post a .CR2 file?

cfcRebel wrote in post #3492397
It depends a lot on how well you expose the shot in the 1st place. Even at ISO100, if the shot is underexposed, you'll see some noise.

I am not aware of any noise reduction done on jpeg in the camera. I know there is a custom function to apply noise reduction for long exposure but that's for unique occasion. The jpeg version of a photo (straight from camera) has the same amount of noise as its raw counterpart if not more, depending on the Sharpening parameter in the camera that you set. Sharpening accentuates noise. Not sure about DPP (i guess it's the same) when viewing a photo via RawShooterEssential or ACR, I turn off the preview if I want to see the image without any preset editing. Hope that makes sense.

According to Canon, called them up...LOL, even RAW images do go through the Digic II for processing, it is just not processed "as much" whatever that means. JPEGS and I guess RAW's, go through the DIGIC II image processor to be "processed" and part of that process criteria is noise reduction.

RAW images ARE noisier than straight-out-of-camera JPEG images due to no noise reduction being applied to the images. You have to do the noise reduction yourself, either in a RAW converter or a separte noise reduction software.

ISO 200-6400 20D Tests

Excellent series on Noise, and what to do about it:
Ron Bigelow on Noise -- Part I

PhotosGuy wrote in post #3494984
ISO 200-6400 20D Tests

Excellent series on Noise, and what to do about it:
Ron Bigelow on Noise -- Part I

Excellent resource, thank you.