jks_photo
11-23-2010, 02:50 AM
I guess the title says it all.
My reason for askiing is because I came across some people that say my pictures are less noisy at the same ISO because I shoot raw.
Is there truth to this????
Though I do shoot RAW I seldom apply NR in post process.
Trondster
11-23-2010, 08:05 AM
When shooting JPEG, the camera attempts to reduce noise for you.
When shooting RAW, you have the ability to control how to reduce the noise. When you remove noise yourself, you can adjust the noise reduction parameters and achieve a more pleasing result. So yes - shooting in RAW can amongst other things help you to reduce image noise in a more pleasing way.
tkerr
11-23-2010, 04:16 PM
A little more fyi about Jpegs.
http://en.wikipedia.org/wiki/JPEG ("http://en.wikipedia.org/wiki/JPEG)
As the typical use of JPEG is a lossy compression ("http://en.wikipedia.org/wiki/Lossy_compression)
method, which somewhat reduces the image fidelity, it should not be
used in scenarios where the exact reproduction of the data is required
(such as some scientific and medical imaging applications and certain
technical image processing ("http://en.wikipedia.org/wiki/Image_processing) work).
JPEG is also not well suited to files that will undergo multiple
edits, as some image quality will usually be lost each time the image is
decompressed and recompressed, particularly if the image is cropped or
shifted, or if encoding parameters are changed – see digital generation loss ("http://en.wikipedia.org/wiki/Digital_generation_loss)
for details. To avoid this, an image that is being modified or may be
modified in the future can be saved in a lossless format, with a copy
exported as JPEG for distribution.
The compression method is usually lossy ("http://en.wikipedia.org/wiki/Lossy_compression),
meaning that some original image information is lost and cannot be
restored (possibly affecting image quality.) There is an optional lossless ("http://en.wikipedia.org/wiki/Lossless_JPEG) mode defined in the JPEG standard; however, that mode is not widely supported in products.
RAW Image Format:
http://en.wikipedia.org/wiki/Raw_image_format ("http://en.wikipedia.org/wiki/Raw_image_format)
Nearly all digital cameras can process the image from the sensor ("http://en.wikipedia.org/wiki/Charge-coupled_device) into a JPEG file using settings for white balance, color saturation ("http://en.wikipedia.org/wiki/Saturation_%28color_theory%29), contrast ("http://en.wikipedia.org/wiki/Contrast_%28vision%29), and sharpness ("http://en.wikipedia.org/wiki/Unsharp_masking)
that are either selected automatically or entered by the photographer
before taking the picture. Cameras that produce raw files save these
settings in the file, but defer the processing. This results in an extra
step for the photographer, so raw is normally only used when additional
computer processing is intended. However, raw has numerous advantages
over JPEG such as:
Higher image quality. Because all the calculations (such as applying gamma correction ("http://en.wikipedia.org/wiki/Gamma_correction), demosaicing ("http://en.wikipedia.org/wiki/Demosaicing), white balance, brightness ("http://en.wikipedia.org/wiki/Brightness),
contrast, etc...) used to generate pixel values (in RGB format for most
images) are performed in one step on the base data, the resultant pixel
values will be more accurate and exhibit less posterization ("http://en.wikipedia.org/wiki/Posterization).
Bypassing of undesired steps in the camera's processing, including sharpening ("http://en.wikipedia.org/wiki/Sharpening) and noise reduction ("http://en.wikipedia.org/wiki/Noise_reduction)
JPEG images are typically saved using a lossy compression format (though a lossless JPEG ("http://en.wikipedia.org/wiki/Lossless_JPEG)
compression is now available). Raw formats are typically either
uncompressed or use lossless compression, so the maximum amount of image
detail is always kept within the raw file.
Finer control. Raw conversion software allows users to manipulate more parameters (such as lightness ("http://en.wikipedia.org/wiki/Lightness_%28color%29), white balance, hue ("http://en.wikipedia.org/wiki/Hue),
saturation, etc...) and do so with greater variability. For example,
the white point can be set to any value, not just discrete preset values
like "daylight" or "incandescent". As well, the user can typically see a
preview while adjusting these parameters.
Camera raw files have 12 or 14 bits of intensity information, not the gamma-compressed ("http://en.wikipedia.org/wiki/Gamma_correction)
8 bits stored in JPEG files (and typically stored in processed TIFF
files); since the data is not yet rendered and clipped to a color space ("http://en.wikipedia.org/wiki/Color_space) gamut ("http://en.wikipedia.org/wiki/Gamut), more precision may be available in highlights, shadows, and saturated colors.
The color space ("http://en.wikipedia.org/wiki/Color_space) can be set to whatever is desired.
Different demosaicing ("http://en.wikipedia.org/wiki/Demosaicing) algorithms can be used, not just the one coded into the camera.
The contents of raw files include more information, and potentially
higher quality, than the converted results, in which the rendering
parameters are fixed, the color gamut is clipped, and there may be quantization ("http://en.wikipedia.org/wiki/Quantization_%28image_processing%29) and compression ("http://en.wikipedia.org/wiki/Compression_artifact) artifacts.
Large transformations of the data, such as increasing the exposure
of a dramatically under-exposed photo, result in less visible artifacts
when done from raw data than when done from already rendered image
files. Raw data leave more scope for both corrections and artistic
manipulations, without resulting in images with visible flaws such as posterization ("http://en.wikipedia.org/wiki/Posterization).
All the changes made on a RAW image file are non-destructive; that
is, only the metadata that controls the rendering is changed to make
different output versions, leaving the original data unchanged.
To some extent, RAW photography eliminates the need to use the HDRI ("http://en.wikipedia.org/wiki/HDRI)
technique, allowing a much better control over the mapping of the scene
intensity range into the output tonal range, compared to the process of
automatically mapping to JPEG ("http://en.wikipedia.org/wiki/JPEG) or other 8-bit representation.
neuroanatomist
11-23-2010, 10:01 PM
Yes, RAW images will be less noisy than straight-from-the-camera JPGs. Also, not all RAW converters are created equal. Here's a comparison shot from my PowerShot S95, shot in RAW, processed with the default NR settings in DPP vs. DxO. This was shot at ISO 640 (the crop factor for the S95 is 4.6, so this is approximately equivalent to ISO 3200 on FF or ISO 2000 on a crop sensor).<span>
<div>/cfs-file.ashx/__key/CommunityServer-Components-UserFiles/00-00-00-35-15/DPPvsDxO_2D00_Noise.jpg</div>
As you can see from the whole image and the 100% crops, DxO does a better job at NR.
When post processing raw files, on the other hand, the software can take as long as long as you want,
To follow on from that, DPP takes about 30 seconds to process each 10 MP RAW image, while DxO takes well over a minute.