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Author Topic: The Canon DR issue and post-processing - interesting article  (Read 2644 times)

NancyP

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The Canon DR issue and post-processing - interesting article
« on: February 05, 2015, 06:54:27 pm »

Now maybe this approach is not new to you, but it is to me. Admittedly I am but a babe in the woods of post-processing. It seems that some of the DR "lost" by a significantly large Canon signal processing offset addition can be recovered in post by changing the offset (black point)to avoid data clipping, then work rgb curves, then work separate channel curve if needed to equalize channel signal (if shadows are indeed neutral). I will have to play a bit with this idea.

http://www.clarkvision.com/articles/canon.raw.processing1/
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dwswager

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Re: The Canon DR issue and post-processing - interesting article
« Reply #1 on: February 05, 2015, 07:57:10 pm »

Now maybe this approach is not new to you, but it is to me. Admittedly I am but a babe in the woods of post-processing. It seems that some of the DR "lost" by a significantly large Canon signal processing offset addition can be recovered in post by changing the offset (black point)to avoid data clipping, then work rgb curves, then work separate channel curve if needed to equalize channel signal (if shadows are indeed neutral). I will have to play a bit with this idea.

http://www.clarkvision.com/articles/canon.raw.processing1/

This is a way to pull shadow detail out of a Canon Raw.  It does not alter the ability of the sensor to capture more Dynamic Range.  The DR of the sensor is that difference in EV between when the signal from the pixel rises above the noise floor such that the camera can tell it is a signal to the point at which the pixel becomes saturated and cannot generate any additional signal.  No amount of post processing will change that.  However, proper post processing can maximize it.  The other downside to the Canon sensor is the shadow noise that gets accentuated when pulling detail compared to the Sony sensors.

There are ways to reduce the dynamic range necessary.  For example, shooting sunsets with a cyan filter will retard the red channel from clipping.
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Bart_van_der_Wolf

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Re: The Canon DR issue and post-processing - interesting article
« Reply #2 on: February 06, 2015, 05:34:52 am »

Now maybe this approach is not new to you, but it is to me. Admittedly I am but a babe in the woods of post-processing. It seems that some of the DR "lost" by a significantly large Canon signal processing offset addition can be recovered in post by changing the offset (black point)to avoid data clipping, then work rgb curves, then work separate channel curve if needed to equalize channel signal (if shadows are indeed neutral). I will have to play a bit with this idea.

http://www.clarkvision.com/articles/canon.raw.processing1/

Hi,

This is a specific suggestion for improving the ACR raw conversion process, and it shows how mediocre the default settings can work out.

Other Raw converters may deal differently with these issues, but it does help to get the Raw conversion done as right as possible before further processing. There is also the possibility to average multiple exposures (e.g. in Photoshop), on static subjects like product or architecture photography (if the lighting cannot be controlled enough).

Cheers,
Bart
« Last Edit: February 06, 2015, 05:39:51 am by BartvanderWolf »
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NancyP

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Re: The Canon DR issue and post-processing - interesting article
« Reply #3 on: February 06, 2015, 11:28:41 am »

Thanks. I guess my point is that maybe some of the less experienced "DRones" could get more out of their files in post processing. I think that I need to improve my skills before I start wanting a new camera to deal with limitations, because I may not have the most accurate idea of the scope of the limitations, and whether it is a practical issue for me  warranting more money spent on body vs. lens or trip somewhere or...
I just hate usual gaudy HDR, renamed "Clown vomit" by the local certified Lightroom instructor. Learning blending techniques on Photoshop is one of my New Year's resolutions. I have Nik HDR program, and often I just don't care for the results even on the most "naturalistic" settings. It seems likely that I need to tweak the black cut-off and maybe the curves identically on all input images before taking them over to Nik HDR.
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dwswager

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Re: The Canon DR issue and post-processing - interesting article
« Reply #4 on: February 06, 2015, 11:37:34 am »

Thanks. I guess my point is that maybe some of the less experienced "DRones" could get more out of their files in post processing. I think that I need to improve my skills before I start wanting a new camera to deal with limitations, because I may not have the most accurate idea of the scope of the limitations, and whether it is a practical issue for me  warranting more money spent on body vs. lens or trip somewhere or...
I just hate usual gaudy HDR, renamed "Clown vomit" by the local certified Lightroom instructor. Learning blending techniques on Photoshop is one of my New Year's resolutions. I have Nik HDR program, and often I just don't care for the results even on the most "naturalistic" settings. It seems likely that I need to tweak the black cut-off and maybe the curves identically on all input images before taking them over to Nik HDR.

Yes, getting the RAW conversion correct can really help save some images and significantly improve the quality of others.  As long as the signals are not clipped, there is data there.  The Canon sensors unfortunately lack DR and introduce more noise to the shadows making it more difficult to work with.

As to HDR, it depends what you are trying to do.  John Shaw, never one to be accused of over saturation, has a post called HDR (A DIFFERENT WAY).  Basically it converts the image to 32 bits where you can then adjust it in ACR or PS without the Tone Compression over saturation issues.  However, I have images that I have processed as basic photographic images.  And then processed again in Photomatix.  These have some odd lighting effects and additional saturation.  I view them as artistic impressions rather than 'photographs'.  Still pleasing to view.
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NancyP

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Re: The Canon DR issue and post-processing - interesting article
« Reply #5 on: February 06, 2015, 07:54:14 pm »

Thanks for the link and information
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