Daves interstellar foolishness

Started Sep 10, 2012 | Discussions thread
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crames Regular Member • Posts: 192
Re: Armchair technologists fighting!

David Rosser wrote:

Wyville wrote:

bobn2 wrote:

Joofa wrote:

I don't know how science literate Bobn2 is,

Actually, that is a million dollar question on the minds of many here :).

I think 'minds' is a bit of an overstatement for people questioning it. Anyone with a modicum of investigative ability, it is easy to find out.

Oh, come on Bob, I was being serious. I simply don't know and didn't want to accuse you of being a layman. I don't understand the subject myself, so I can't judge your expertise accurately. (Dave is another matter though.)

You might get a clue here (section 5)


Yes, the clues in that article are the errors in just the first few paragraphs (didn't want to read any further). The following quotes are from that article:

"The eye can see more detail in monochrome because there are more monochromatic detectors (rods) than there are colour ones (cones)"

Two seconds with Google or Wikipedia will show that the rods are not active at the light levels of normal color vision, and are not even present in the fovia, the part of the retina with the highest resolution capability.

"Effectively, the two green channels act as a single sampling grid, sampling every other pixel rotation, but rotated by 45°, which means that in the vertical and horizontal directions the green or luminance channel is sampled every 1.414 (square root of two) pixel spaces."

Actually the combined green channels have full resolution in the the horizontal and vertical directions, it is the diagonal directions which are sampled at a lower rate.

Ref: Li, et al "Image Demosaicing: A Systematic Survey" http://www.csee.wvu.edu/~xinl/papers/demosaicing_survey.pdf

"Thus, not only is the amount of light increased, but so is the number of samples taken in the luminance channel (now the only channel), which is the one that provides the detail in the image. The gain is 1.414 times as many samples in each direction, totalling twice as many samples. This means that an 18-million-pixel monochrome sensor will produce the same amount of luminance information (otherwise known as detail) as a 36-million-pixel Bayer sensor."

Actually, from the same figure it can be seen that the 18 MP monochrome sensor will produce the same amount of information only in the diagonal directions. The vertical and horizontal resolution of the 36 MP Bayer will be higher.

To be fair, this could just be poor editing on the part of the magazine. Just the same, I don't think that anyone can be fully "science literate" in all areas of science.

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