The first thing that gets my attention in the red filter is that there
are values of more than 100% while the B/W filter's values are all less
than 100%. In particular, in the red filter the red and magenta are at
120% and the yellow at 110%. Does this mean that any red pixel is
multiplied by 1.2? I don't know exactly what it means but if it does
mean multiply pixel values by 1.2 then any pixel of 213 or higher will
create a blown pixel.
I note that the B/W filter with values all less than 100% produced a
good looking image without noise or pixelation. Perhaps if the red
filter's values were divided by 1.2 you'd get proportional numbers
without causing blown highlights.
That would give values of:
> Reds 100%
> Yellows 92%
> Greens -8%
> Cyans -42%
> Blues 0%
> Magentas 100%
Chuck Norcutt
C.H.Ling wrote:
> Here is the default Red Filter in CS4:
>
> Reds 120%
> Yellows 110%
> Greens -10%
> Cyans -50%
> Blues 0%
> Magentas 120%
>
> Result:
>
> http://www.accura.com.hk/temp/IMG_2587_BW_Red.jpg
>
> Here is the default B/W Filter in CS4
>
> Reds 40%
> Yellows 60%
> Greens 40%
> Cyans 60%
> Blues 20%
> Magentas 80%
>
> Result:
>
> http://www.accura.com.hk/temp/IMG_2587_BW.jpg
>
> Actually, similar problem happen on 10D and 40D too, it could be the problem
> of CS4.
>
> C.H.Ling
>
>
> ----- Original Message -----
> From: "Chuck Norcutt" <chucknorcutt@xxxxxxxxxxxxxxxx>
>
>> CH was complaining about his 5D Mk II, not his original 5D. Moose and I
>> are still with the 5D. I did not see the noise that CH and Moose say
>> they can see. At 100% magnification I see pixelization in CH's image
>> which ACR's noise control can eliminate. Whether the pixelization is
>> dispensed with or not I see posterization (but not noise) after reducing
>> the size to about 50% or less and after turning off every color except
>> pure red in ACR's B&W converter. If I have only pure red available in a
>> JPEG image I have (at most) 256 shades of gray. That to me is the
>> probable source of the posterization although there are never more than
>> 256 shades of gray in a B&W JPEG. Perhaps the Bayer pattern is a
>> problem if all the blue and green pixels are totally eliminated? If I
>> return blue to the halfway point the posterization goes away.
>>
>> Actually, after mentioning "half way point" I realized that perhaps I'm
>> the problem. The half way point is zero. In turning the red channel to
>> +100% and everything else to -100% perhaps I've boosted half of the red
>> pixels to the point of being blown out. I've never much paid attention
>> to what the scales on those sliders actually mean. Just push them
>> around until I get something I like.
>>
>> Chuck Norcutt
>>
>>
>> Ken Norton wrote:
>>> I don't understand something. How can we have three 5D owners not
>>> agree about noise patterns in their cameras?
>>>
>>> AG
>
--
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