Good to see you back, Tim. It's been a long time since one of these
insightful posts.
Chuck Norcutt
Tim Hughes wrote:
> I read their position paper and I think some of the claims are
> overblown and maybe in some cases specious:
>
> http://www.fujifilm.com/photokina2008/pdf/release/super_ccd_exr_e.pdf
>
>
> It looks like when running in 6Mpixel modes there are some advantages
> in some ways, but not really in 12 mpixel mode. The mode with
> increased dynamic range is an example where it maybe a fairly good
> tradeof, but you land up in a mode pretty close to 6Mpixel rather
> than 12.
>
> For example it appears the traditional beyer pattern, which is
> optimised for highest resolution in green, since this is human eyes
> peak sensitivity and peak sunlight wavelength, will have higher
> horizontal resolution than the new exp pattern. This actually even
> adds a little more since the eye/brain aparently also subjectively
> percieves it to be highest reolution if it has greatest resolution in
> the horizontal direction.
>
> The new exp patern is quite strange in that the highest resolution in
> green is on the left diagonal , with all other directions being
> lower! This is non-optimal since horizontal is best subjectively. The
> beyer has equal, but reduced by 45% resolution on both
> diagonals,while the vertical and horizontal are the the highest and
> equal.
>
> The exr horizontal green resolution, is lower than the beyer, at
> 12Mpix because of diagonal pattern. Because of the unsymetrical
> spacing of exp, it also aliases at even lower resolution than you
> would normally imagine from that raw color pixel count. If you
> photographed a thin curved line object like a hair say, it would
> produce some additional low frequency aliasing because sampling was
> more non-uniform ,at different angles than beyer. (think: if a line
> pair is sampled by two close spaced pixels then they get resolved,
> but the next pair of pixels in exp are now more widely spaced, so the
> next adjacent line pair is not resolved)
>
> The wide dynamic range option which is really more like 6mpixel,
> since it selects best exposure from two diagonal pixels, then has
> uniform sampling, at least at a particular brightness level.
>
> The claim that there is less aliasing from binning diagonally left
> adjacent pixels in exr, rather than more widely separated ones
> (bayer), is complex to analyse and is more orientation dependent than
> beyer.
>
> However, because the beyer samples at a higher horizontal frequency
> than the non-uniform exr, then binning two horizontal (or vertical)
> pixels in beyer, still has lower aliasing, since the actual sampling
> was done at a higher resolution (frequency) thus having lowest
> aliasing.
>
> The s/n ratio improvement is exactly the same for equal area
> photo-diodes in the two technologies. In this comparison for the
> bayer at 6mpixels, the optimal bining for best subjective and actual
> resolution, would be combining vertical pixels.
>
> Tim Hughes
>
>
>
>
> --- On Fri, 5/1/09, usher99@xxxxxxx <usher99@xxxxxxx> wrote:
>
>> From: usher99@xxxxxxx <usher99@xxxxxxx> Subject: [OM] clever use of
>> available sensor real estate To: olympus@xxxxxxxxxxxxxxxxx Date:
>> Friday, May 1, 2009, 2:12 PM
>> http://www.dpreview.com/reviews/fujifilmf200exr/page2.asp
>>
>> Moose might be amused that low light performance a few generations
>> later still doesn't really exceed the F30/31--the latter are still
>> expensive.
>>
>> Not many Moose sightings of late.
>>
>> A Trace Worried Mike --
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