Pixel density revisited

Started Oct 22, 2008 | Discussions thread
natureman Veteran Member • Posts: 3,979
Re: Pixel density revisited

bobn2 wrote:

natureman wrote:

bobn2 wrote:

Phil Askey wrote:

I think a 30+ page review correctly qualifies any statement about
pixel density and noise. Where is this reverse evidence?

It could be any length, but if it didn't contain any statements
relating noise content to final output size, it wouldn't be
qualified, would it? I've read through it quite carefully, and I
can't find any pointer there that would help me understand the
relative noise between the cameras for usual output sizes. There are
a lot of statements about how noisy the A900 is, but all related to
per pixel noise.

There's nothing "absolute" about "final output sizes". 100%
magnification is "absolute" and "qualified" and so is "per pixel
noise".

I agree with the first part of the statement - of course, since final
output sizes vary, there is nothing absolute. I disagree strongly
with the second, there is nothing 'absolute' either about 100% or per
pixel noise. For a start, the 'pixel' you are looking at on the
screen is an amalgam of data from a number of sensor elements,
combined together using an algorithm you know nothing of, with
unknown effects on the noise. As for qualified, that depends on the
qualifications, and 'per pixel noise' is not qualified in an easily
understandable way to the level or quality of noise apparent in a
viewed image.
Really, you are playing around with semantics, both in your use of
'absolute' here, and 'fair' in previous posts. Big words like
'absolute' and 'fair' sound fine and dandy, but, as I've tried to
point out before, for comparative reviews what's important is
usefulness and objectivity. Given that most people (admittedly not
all) buy cameras as devices for taking photographs, a useful test is
one that gives a clear indication of the likely quality of those
photographs and an objective test is one that produces an unbiased
assessment of the likely quality of those photographs. The measuring
and emphasising of tests that do not directly relate to output image
quality and then asserting that they do fails on both counts.

In your previous post you said "It could be any length, but if it didn't contain any statements relating noise content to final output size, it wouldn't be qualified, would it?"

What I'm saying is that dpreview does qualify it by showing 100% comparison images from every camera in their reviews. In other words, all cameras are compared at equal magnification and the amount of magnification is specified, and that qualifies their analysis and comparisons. In even more other words, the qualification is the fact that all cameras are compared at an equal, specified magnification of their images (100%). The results (noise, etc.) are shown on the basis of that qualification.

They also show some images at other magnifications.

Regardless of pixel density, dpreview is showing what each camera produces at its' maximum native output size, when they show comparisons at 100%, and that is as objective as anyone can get. I don't know about the rest of you but if I want to see what a camera will do, noise-wise or anything else, at a particular print size, I can just resize the 100% images myself.

There are other things in the reviews that to me are not objective/unbiased (like the lenses used) but comparing images at 100% is proper.

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