I must be blind. I didn't open this file before because my CS3 can't
handle 5D MkII files. However, I decided to try an ACR conversion in my
trial version of Elements which does handle it. I do see banding on the
wood paneling in the background at lower far right. But to make it
visible I have to increase fill light to 100 while also increasing
exposure by a full stop. That's something I'd never do. Are my new
eyes or monitor that bad?
Chuck Norcutt
C.H.Ling wrote:
> Moose, I think you are right, it is highly possible A/D problem, I have
> checked with some low ISO images, there are large size "noise" at the shadow
> area even without boost up, what 14 bit A/D seems not doing better than the
> E-1, all are BS, even the 40D images look better.
>
> There has been a long time curious for me why some OOF background didn't
> look as smooth as they should be, it was not enough bit deep. Now there is
> one more thing to look for when checking out a new camera.
>
> C.H.Ling
>
>
> ----- Original Message -----
> From: "C.H.Ling"
>
>> Yes, there is similar problem even at full resolution:
>>
>> http://www.accura.com.hk/temp/IMG_6442.CR2 (23MB)
>>
>> I really have no idea how this happen as a totally dark low ISO image is
>> very clean even boost up, at the mean time high ISO image is clean except
>> the shadow, just like problem with low ISO image.
>>
>> C.H.Ling
>>
>> ----- Original Message -----
>> From: "Moose"
>>
>>> C.H.Ling wrote:
>>>> ...
>>>>
>>>> Just found another phenomenon, when I shot a dark frame at the same ISO
>>>> and shutter speed (ISO125, 1/8s) of the problem image. The dark frame
>>>> came out totally dark even I push it two stops so I can't use the dark
>>>> frame subtraction method to cancel the pattern.
>>>>
>>>> The pattern noise only appear on the area that is not totally dark so it
>>>> doesn't like a hardware (circuit noise) problem, may be a firmware
>>>> update
>>>> can really solve it?
>>>>
>>> As I think about this, I wonder if the effect is the same regardless of
>>> the resolution at which the shot is taken. A repeating pixel level
>>> pattern could result from the way adjacent pixels are merged (I assume
>>> they are merged?) for the smaller sizes, like the 5.2 MP version you
>>> posted. If so, a firmware solution may be possible.
>>>
>>> I didn't expect dark frame subtraction to help. That's a different sort
>>> of issue without any pattern.
>>>
>>> I think it was AG, earlier in this thread who suggested it could be a
>>> demosaicing artifact. I could see how that could be the case, although I
>>> don't see any meaningful difference using the three algorithms available
>>> in RawTherapee.
>>>
>>> Down at the bottom of the brightness range, the nature of linear digital
>>> coding means that there are very few different numerical values
>>> available to represent shades of brightness.
>>>
>>> Whatever the analog ability of the sensor to react to tiny differences
>>> in light, the analog voltages have to be encoded digitally. Perhaps this
>>> is some sort of quantization effect where tiny diffrences in voltage are
>>> forced into "buckets" with average values that create too much contrast
>>> between pixels. This could magnify any subtle pattern of sensor site
>>> sensitivity differences resulting from physical sensor design.
>>>
>>> If that's the source, it may require a hardware changes, perhaps to the
>>> Ato D converters.
>>>
>>> (Now that I think of it, at what point do the sensor sites start showing
>>> the effects of the number of individual light quanta that they sense?)
>>>
>>> Moose
>
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