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Interpolate luminance and chrominance before writing to dng

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Offline dvip

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Interpolate luminance and chrominance before writing to dng
« on: 16 / November / 2014, 19:57:53 »
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Is it possible reduce or get rid of luminance and chrominance noise
before writing the buffer to the dng file?
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Offline waterwingz

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #1 on: 16 / November / 2014, 20:03:08 »
Quote from: dvip on 16 / November / 2014, 19:57:53
Is it possible reduce or get rid of luminance and chrominance noise before writing the buffer to the dng file?
My guess? 

It should be possible to act on the RAW buffer prior to it getting saved as a DNG. 

But implementing an effective filter for luminance or chrominance noise in C that runs as a camera task would be a big job. You'd need a whole lot of filter and digital image processing expertise to even attempt to code something like that.  AFAIK, Canon uses the DSP part of the Digic chip to do that sort of thing - not C code in the ARM side of the house.


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Offline koshy

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #2 on: 16 / November / 2014, 21:11:46 »
Quote from: dvip on 16 / November / 2014, 19:57:53
Is it possible reduce or get rid of luminance and chrominance noise
before writing the buffer to the dng file?
Noise reduction always impacts detail. IMO there is no one size fits all solution to this task and attempting to create one in camera would eliminate a key benefit of writing raw images in the first place - that you can process them whichever way you please later. You don't have any surplus information to factor into the noise removal in camera so why take the supposed "raw" another step farther away from an actual sensor read out?
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Offline dvip

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #3 on: 16 / November / 2014, 22:06:19 »
@waterwingz,
True, C code + ARM may not have enough power to do it fast. It may also add some delay before writing data to the DNG, which already takes time as it is. Better to do it at PP time on the PC. Thanks anyway.
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Offline sequencer

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #4 on: 19 / November / 2014, 16:44:09 »
I myself would love to see more chdk image quality improvements and development.  Things haven't changed much in chdk over the years regarding raw/dng and image quality. Perhaps there isn't much more to be done due to hardware limitations. Shooting raw is great with these cameras and chdk made this possible. I would say, implementing in-camera noise control could be a challenging task.
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Offline reyalp

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #5 on: 19 / November / 2014, 22:19:16 »
Quote from: sequencer on 19 / November / 2014, 16:44:09
I myself would love to see more chdk image quality improvements and development.  Things haven't changed much in chdk over the years regarding raw/dng and image quality.
The whole point of using raw is to capture the original data from the sensor, so you can do the image processing on a PC. The PC is far more powerful, has a huge amount of image processing software already available, and is much easier to write your own code for.
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Offline koshy

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #6 on: 20 / November / 2014, 20:30:25 »
Quote from: reyalp on 19 / November / 2014, 22:19:16
The whole point of using raw is to capture the original data from the sensor, so you can do the image processing on a PC. The PC is far more powerful, has a huge amount of image processing software already available, and is much easier to write your own code for.
One very important factor in it I'd like to add is that with aRAW image you get an original file that is not changed in any unnecessary way and from which you can create as many derivates as you'd like. Altering this data in camera in a needless way destroys the original. On the PC you’ll keep it if you want to.
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Offline dvip

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #7 on: 22 / November / 2014, 15:37:06 »
>haven't changed much in chdk over the years regarding raw/dng

@sequencer,
I remember a "writing to dng" speed up improvement which was nice.

@reyalp,
Yep, raw is raw :)

Thanks guys.
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Offline waterwingz

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #8 on: 22 / November / 2014, 15:53:30 »
Quote from: dvip on 22 / November / 2014, 15:37:06
@sequencer,
I remember a "writing to dng" speed up improvement which was nice.
Not to mention support for both DNG 1.1 & DNG 1.3 and (even better) the ability to set crop size (Full/Active/JPEG).
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Offline dvip

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Re: Interpolate luminance and chrominance before writing to dng
« Reply #9 on: 28 / November / 2014, 12:57:11 »
One thing I would like to see is a way to add a small memo, notes, copyright, or something like that to the DNG exif. Perhaps it can be read from a text file in the SD card and then inserted in the DNG.
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