Too many megapixels? Six is enough for an 8x10.

Started Apr 26, 2009 | Discussions thread
bobn2
bobn2 Forum Pro • Posts: 61,160
Re: Too many megapixels? Six is enough for an 8x10.

Anastigmat wrote:

bobn2 wrote:

So we'll pitch your view about the 'tones' against quantitative
measurements taken by experts and the subjective opinions of may
professional photographers. Right.

Pros are unlikely to use the D40, so they are also unlikely to have
an opinion about it. Besides, many pros are just as ignorant about
photo equipment as you or I.

or him, for that matter. I'd trust properly conducted measurements over some bloke's opinion any day.

I wonder who are the gullible.... Those who keep upgrading to new
cameras with more but smaller pixels thinking that they will get
better image quality because of the increased pixel count. Of
course, there are definitely enough of these consumers to keep the
upgrade market busy and healthy.

Well, they will get better image quality because of the increased pixel count. I would agree, that for many the improvement might not be enough to justify the expenditure, but there are some who alwways have to have the latest and best.

So, you pay oodles of money for a 15-24mp sensor, so you can
downsample it to match the quality of a 6mp sensor?

It doesn't cost any more, and gives better quality when downsampled. True, new models sell at a premium over older ones, but that has little or nothing to do with increased cost of the sensor.

Why not save the
money and use it for something better?

What extra money?

I am not against higher
resolution, but not at the expense of increased noise.

Thats good, because it never seems to give increased noise.

Besides, downsampling is not easy:

Dead easy if you've got a Canon with sRAW. Wasn't it you who was pointing out how much better 10MP Canon sRAW was than 12MP NEF? Or maybe it was Taikonaut - I get confused sometimes.

'Before answering the question in detail of "does it work and how
well" (yes it does, and very well) we need to understand that
"binning" has been done before, but rarely with a colour matrix
sensor and never very well. Monochrome sensors have been binned, but
doing so with a Bayer matrix is a monumentally more difficult task
because each adjacent pixel is of a different colour and has a quite
different spectral response. Also, because binning reduces resolution
by a factor of four, it really doesn't make a lot of practical sense
to attempt unless and until one has a sensor such as the one in the
P65+, with 60 megapixels unbinned. The resulting 15 megapixel binned
size is bigger than many pro DSLRs, such as the Nikon D3 and D700,
and therefore quite usable for many commercial applications.'

'Binning' is cahrge accumulation on the sensor, which I don't believe any camera does (could be wrong, I'd be happy to be informed better). But essentially, you are right. Rather than demosaicing and downsampling, it would be much better to have a downsampling raw converter (which is, I suppose, what sRAW is). I wonder why there isn't one?
(end part 1)
--
Bob

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