Archived posting to the Leica Users Group, 2008/09/03
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]Right, film does this too but the unfortunate thing with digital is
that the transitions are at times a bit abrupt, so more of a banding
effect can show up. Shooting RAW makes it possible to reduce this.
>Actually, this occurs with transparency films as well. Around the over
>exposed highlights, you will see colour fringes, and that's mostly not
>because of the chromatic aberrations.
>
>On Wed, Sep 3, 2008 at 9:01 AM, Henning Wulff
><henningw@archiphoto.com>wrote:
>
>>
>> Actually, the 'chromatic' issues around highlights are not a function of
>> the lens, but of the sensor and the light qualities that hit it.
>>
>> Highlight blowout is due to sensor saturation, ie, the sensor cannot
>> register the actual number of photons that have hit it as it's a number
>> that's bigger than what it's maximum. Near the actual highlight, where
>> every
>> channel is blown out, is a region where some channels are saturated, but
>> not
>> other(s). That will give areas or rings around the highlights of colours
>> that have not yet saturated. Because some channels have saturated in this
>> region, the colours will be false as the saturated channels cannot
>> provide
>> the proper value.
>>
>> All digital sensors will do this, but unless the highlight areas are
>> large
>> with gradual transition areas, it won't be a problem. There are some
>> workarounds, but they involve 'creating' some colour values in this
>> region.
>>
>
>
>
>--
>Ken Iisaka
>first name at last name dot org or com
>
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--
* Henning J. Wulff
/|\ Wulff Photography & Design
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