Pixel Density is GENIUS!

Started Jul 13, 2008 | Discussions thread
simpy Veteran Member • Posts: 3,090
Re: skewed comparison

RRJackson wrote:

I don't know how well this holds up theoretically, but practically I
used to print down a size to minimize grain. I basically had to halve
the print size to gain a stop of "NR" so I'd go from an 8x10 to a 5x7
if I wanted the image, but wasn't happy with the prominence of grain.
It didn't seem to make a noticeable (or rather practical) difference
until I'd halved the print size (roughly, since a 5x7 is actually a
little less than half). If this holds true with digital noise (and I
haven't printed much of my own digital output...I have a little
dye-sub for quick prints, but I send out for enlargements) then the
jump from (for example) 8 to 12 megapixels would be a losing game. It
seems like you have to be talking about a sensor with twice the
density. At which point the level of light where the sensor's output
became unusable even with scaling would be lower, as well. I don't
see any advantages to it. That's not to say that there aren't any,
but I can't see them from a practical sense.

Printing at smaller sizes to suppress grain (noise) is indeed exactly equivalent to downsampling.

As to whether it is better or not to start with extra pixels, if you do the math, you'll see that it actually makes no difference (assuming constant read noise per unit area).

But I'd much rather use a sensor that's
suited well to a wide variety of operating conditions than one that
can be scaled and blurred and noise-reduced enough to be kind of
acceptable if you make it small enough.

No, the more flexible sensor is the one with more pixels. It can be made exactly as 'acceptable' as the low pixel count sensor at smaller print sizes, but it has the additional benefit of using the extra resolution when needed.

I printed larger than 8x10 three times last year. Had to think about
it. I used to do it a lot more often, but I'm not that active right
now. So I'll certainly admit that printing large isn't an everyday
occurrence for me. But then we need to decide whether we're looking
for technology that's optimal or passable.

Optimal, optically speaking, would be a sensor that is as large as possible, because it gives you most flexibility. In practice, you'll always get what's passable for your particular needs and budget (money, size, weight, etc.).

I think I need to clarify one thing, though. The pixel density can be calculated from the size and MP count. What you seem to be arguing is that at a given MP count, decreasing the pixel density leads to better quality through the larger sensor size. No argument from me, but the fact that it is clearer to talk about the sensor size directly.

The rest of this thread is about what happens if you keep the sensor size constant. In that case, is increasing the MP count a good thing or a bad thing? My point is it definitely doesn't need to be a bad thing.

Simon

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