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Canon noise reduction

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Offline vit40

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    Re: Canon noise reduction
    « Reply #10 on: 10 / May / 2008, 03:08:17 »
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    Hi,
    The noise reduction options on the raw parameters menu page are mis-named.  They should be called dark frame subtraction.  That is because Canon also does other noise reduction that this option does not affect...

    Jon

    You are absolutely right ... but dark frame subtraction is called "noise reduction" in most cameras with this option in firmware menus (even Canon DSLRs)

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    Re: Canon noise reduction
    « Reply #11 on: 10 / May / 2008, 12:36:29 »
    The SD is only very slightly reduced, this may be experimental error.

    I feel like I am back in school in a lab course.  Here is a better experiment:  Out of focus beige wall taken at ISO 800 and re-developed at 80,100,200,400,800,1600.  The results show that there is no noise reduction at ISO 100. There is mostly luminance noise reduction at ISO 200.  At 400-1600 there is increasing chroma noise reduction. 
    First line for each image is results on the RGB image, next is Y, next is CbCr (color).
    Sorry that the columns don't line up.  StdDev is the important column.
               Area   Mean   StdDev   Min   Max   
    ISO80   890028   138.940   11.135   83   202   
    Y----   890028   141.582   10.983   83   202   
    CbCr   890028   126.832   2.196   115   136
       
    ISO100   890028   138.794   11.192   82   202   
    Y----   890028   141.833   11.038   85   202   
    CbCr   890028   126.435   2.198   115   136
       
    ISO200   890028   137.664   8.133   90   191   
    Y----   890028   141.076   7.875   94   194   
    CbCr   890028   126.067   2.137   114   135
       
    ISO400   890028   138.593   5.764   98   180   
    Y----   890028   142.541   5.702   102   184   
    CbCr   890028   125.590   0.852   121   129
       
    ISO800   890028   138.177   4.278   110   166   
    Y----   890028   141.847   4.255   115   170   
    CbCr   890028   125.873   0.595   123   128
       
    ISO1600   890028   195.545   3.557   171   214   
    Y----   890028   199.407   3.463   175   218   
    CbCr   890028   125.641   0.738   123   128   


    « Last Edit: 10 / May / 2008, 12:40:43 by hiker_jon »

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    Re: Canon noise reduction
    « Reply #12 on: 30 / May / 2008, 10:41:47 »
    Well, when there is NR applied to the "RAW"-images, then it  is NOT a RAW any more... ;)

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    Offline BB

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    Re: Canon noise reduction
    « Reply #13 on: 30 / May / 2008, 11:44:38 »


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    Re: Canon noise reduction
    « Reply #14 on: 01 / June / 2008, 05:33:47 »

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    Re: Canon noise reduction
    « Reply #15 on: 01 / June / 2008, 10:56:12 »
    « Last Edit: 01 / June / 2008, 11:00:13 by hiker_jon »

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    Offline PhyrePhoX

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    Re: Canon noise reduction
    « Reply #16 on: 01 / June / 2008, 11:22:10 »
    easy (i suppose :D). shoot at iso 800. save the raw file, delete the jpg. set camera to iso 80. develop the raw. outcome should be without the huge nr. shouldnt it?

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    Offline BB

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    Re: Canon noise reduction
    « Reply #17 on: 01 / June / 2008, 12:04:56 »
    « Last Edit: 01 / June / 2008, 12:08:03 by BB »


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    Offline RaduP

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    Re: Canon noise reduction
    « Reply #18 on: 01 / June / 2008, 20:45:59 »
    I think the camera ALWAYS does some NR or some post processing of the raw date, because my camera has a one 'dead' (always on) red pixel, and if I shoot in raw, then there is only 1 dead pixel that is hard to see.
    However, the camera JPEG amplifies that dead pixel by doing some sort of averaging I guess, and it becomes bigger and uglier. The sharpness is set on soft, because otherwise my camera would make that dead pixel huge, overpowering all the adjacent pixels.

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    Offline vit40

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    Re: Canon noise reduction
    « Reply #19 on: 02 / June / 2008, 03:29:41 »
    Did you try bad pixel mapping, one of CHDK features ?

    Anyway, even ACR does some NR with NR (luma and chroma) set to zero. It can be reduced by lowering the value of appropriate tag in dng file, resulting in sharper picture (and higher noise)

     

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