[QuadList] IVC Recovery--"Capture" and "Banding"--

[Steve White]

Thanks, Ted, for the supplemental detail.  All interesting.


On 5/18/14, 12:33 AM, Ted Langdell wrote:
>
>
> On May 17, 2014, at 7:17 PM, couryhouse at aol.com 
> <mailto:couryhouse at aol.com> wrote:
>> I just  bring it into digital and hit the  save a  still in Sony   
>> Vegas...   or if I am watching analog    footage in  windows media 
>> player  I do a screen capture..... 
>
> I think what Park meant by "capture an image" was "digitize video" not 
> make a still.
>
> His particular process converts composite video to component using the 
> Accom D-Bridge 10-bit decoder before capture as a file... say as 
> 10-bit YUV 4:2:2 in a Quicktime wrapper.
>
> The D-Bridge products (122 and 221) have roots in companies formed by 
> former Ampex engineers:
>
>     http://www.abekas.com/main/history//page1059.htm
>
>     They were intended to "Bridge" the analog to digital process,
>     including analog composite, D1 parallel and D2 composite.
>
> In a message dated 5/17/2014 4:52:15 P.M. Mountain Standard Time, 
> park at videopark.com <mailto:park at videopark.com> writes:
>> This is a low band color image from the late 60s, taken with a TK-42. 
>>  Notice the lack of banding, hanging dots and cross-color contamination.
>
> The word "banding" can mean two things as related to this post:
>
>     Quad banding... where one sees variations every 16 lines (NTSC)
>     caused by differences in reproduction by each head (EQ, luma,
>     chroma levels for example.)
>
>     Or noticeable bands in light to dark areas of the picture caused
>     by the number of bits used in the digitization process.
>
>     You might see this on say a cyc wall where the top is darker than
>     the bottom. Skies are also an example of where banding might
>     easily occur.
>
>     An 8-bit digitization step (255 steps per color) might be more
>     likely to cause a noticeable bands of luma or chroma. 10-bit
>     digitization provides 1023 steps per color, so banding is less
>     likely to occur.
>
>     Here's Larry Jordan's take on it with a visual example (originally
>     written in 2007 when ProRes was released):
>     http://www.larryjordan.biz/why-video-bit-depth-matters/
>
> More bits and a better representation of the original analog signal is 
> one reason why the generally preferred Archival file for SD is 10-bit 
> YUV 4:2:2, and in a Quicktime wrapper, although some archives use AVI 
> if they're PC based.
>
>
> Ted
>
> Ted Langdell
> Secretary
> Skype: TedLangdell
> e-mail:ted at quadvideotapegroup.com <mailto:ted at quadvideotapegroup.com>
>
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>
>
>
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