Nefertiti's Family

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18 years 6 months ago #10832 by tvanflandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by rderosa</i>
<br />Is the difference in solar longitude enough to cause the following difference in image and histogram?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">No, the difference was caused by fewer grayscale levels in the later image. I'm not sure why you are looking for some other explanation. -|Tom|-

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18 years 6 months ago #10833 by tvanflandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by neilderosa</i>
<br />by "erasing" (as it were) some, or even many, of the dark spots in the "smoothing" or "noise reduction" process, you are in effect "erasing" data which would later appear as shiny spots in another image, and you are thus confusing the issue by tampering with the data.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">But the human eye does the same thing. Some studies will want to preserve what the spacecraft sees that a human cannot see. But for purposes of evaluating hypothetical artistic images, we surely do want to see what the human eye would see if it were there. -|Tom|-

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18 years 6 months ago #15282 by neilderosa
Replied by neilderosa on topic Reply from Neil DeRosa
Originally posted by Tom:<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">But the human eye does the same thing. Some studies will want to preserve what the spacecraft sees that a human cannot see. But for purposes of evaluating hypothetical artistic images, we surely do want to see what the human eye would see if it were there.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">
If I could continue this line of thought a little, I take it you are saying that even though the human eye can see the dark spots, it is legitimate to clean them up somewhat by the "smoothing" process, etc. because that's what the human eye does to some degree anyway, and because this aids us in seeing the feature more clearly.

Can this same line of thinking be applied to animations which hypothetically change the viewing angle of an image? Also can it apply cases where we add "symetricality" to an image, as in the early enhancments that hypothesed on how the "hidden" side of the original Viking images of the Cydonia Face should look?

My sense is that all of these approaches can be acceptable as long as we spell out the type of enhancement we are doing in each case, and retain an understanding of what the real feature actually looks like unenhanced. I used to get the feeling that people tended to forget what the original Viking Face actually looked like, and that certain authors were playing fast and loose with "enhancements," and that this played into our opponents hands.

Neil

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18 years 6 months ago #15283 by rderosa
Replied by rderosa on topic Reply from Richard DeRosa
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by tvanflandern</i>
<br />No, the difference was caused by fewer grayscale levels in the later image.
<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Tom, I guess what I was really asking was: "Why" are there fewer grayscale levels in the later image. I was asking a photography question.

Imagine the two of us were standing in a darkroom, developing our latest picture of the Profile Zone. Say we had been the ones that took M03 and E05. As the image finisihes its processing, we take it out of the tray, and ask each other: why are there fewer grayscale levels?

rd

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18 years 6 months ago #10834 by rderosa
Replied by rderosa on topic Reply from Richard DeRosa
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by neilderosa</i>
<br />If I could continue this line of thought a little, I take it you are saying that even though the human eye can see the dark spots, it is legitimate to clean them up somewhat by the "smoothing" process, etc. because that's what the human eye does to some degree anyway, and because this aids us in seeing the feature more clearly.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">

Neil, remember that we always keep the untouched raw data as part of the process. We can always go back to that.

I think you are raising two different issues. One is: What does the terrain really look like, and the other one is: Assuming there is an artwork rendered there, what does IT really look like (i.e., what was the intent of the artist?)

If we rule out camera noise in the image, I think it's safe to say that the raw data, enhanced maybe just for brightness and contrast (it could have just been taken a little dark, as any photographer knows), IS in fact what it really looks like.

On the other hand, if we're trying to decipher an artwork that may have been put there by some ancient civilization, then I would think that smoothing, which is analogous to a moving average, and histogram equalize, which is spreading the data over the whole range of the eye, is fair game, and desirable, and does not take away needed data.

Sure, you could argue that those black spots, or white spots, were used in the artwork, but that seems like a stretch to me. You could also argue that when we smooth, we accidently take out some of the detail intended by the artist, and that would be true, but I think when we're looking at a face that's a weak argument, because as it smooths, it looks more like a face, not less.

But you're right,though, that there's a fine line. If the artist rendered a birthmark about the size of one of those black spots, the smoothing would not be able to tell the difference between the birthmark and the noise (boulders) in the face.

All told, I think these processes were designed to make people look more like people. Or at least, that's how it works out.

rd

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18 years 6 months ago #10714 by tvanflandern
<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote"><i>Originally posted by rderosa</i>
<br />what I was really asking was: "Why" are there fewer grayscale levels in the later image. I was asking a photography question.<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">To save bandwidth and to allow the transmission of fewer pixels to Earth, both the number of active channels in the CCD detector in the camera, and the number of grayscale levels, were pruned by a factor of two.

<blockquote id="quote"><font size="2" face="Verdana, Arial, Helvetica" id="quote">quote:<hr height="1" noshade id="quote">Imagine the two of us were standing in a darkroom, developing our latest picture of the Profile Zone. ... As the image finisihes its processing, we take it out of the tray, and ask each other: why are there fewer grayscale levels?<hr height="1" noshade id="quote"></blockquote id="quote"></font id="quote">In film photography, the analog of fewer grayscale levels would be a shorter exposure, darkening fewer silver grains. -|Tom|-

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