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James Webb first images – complete set of high resolution shots now live

webbtelescope.org

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Re: James Webb first images – complete set of high resolution shots now live

#271

Post by tsbertalan »

irrational wrote: post #177
whiteboardr wrote: post #93

Earlier quoted context omitted.

I am aware. (And have been eagerly waiting for this moment for ages) It just seems “unscientific” to just use Photoshop and above all curious about the set of rules and algorithms, that enables them to decide which hue to pick for which region, levels, etc.

What tool would you expect them to use instead of Photoshop?

NumPy or Matlab. And it's possible the "original image" is multispectral (more than 3 channels), so you need to choose an arbitrary 3-channel projection.

Re: James Webb first images – complete set of high resolution shots now live

#272

Post by micromacrofoot »

whiteboardr wrote: post #93
roywiggins wrote: post #85

Earlier quoted context omitted.

Webb's primary camera is infrared, so there is by necessity a choice to be made with how to present the data for humans who can't see in infrared.

I am aware. (And have been eagerly waiting for this moment for ages) It just seems “unscientific” to just use Photoshop and above all curious about the set of rules and algorithms, that enables them to decide which hue to pick for which region, levels, etc.

Photoshop is actually more complex than the JWST itself. What makes it "unscientific"? The fact that it's a consumer product?

Re: James Webb first images – complete set of high resolution shots now live

#273

Post by amelius »

GuB-42 wrote: post #128
whiteboardr wrote: post #77

Watching the livestream i was more than surprised, that color correction actually happens in Photoshop. Also, there seem to be multiple layer-masks involved for specific regions and objects. I get that you can shift and composite color, based on hue, apply filters etc, but: Photoshop? Curious if anyone can explain, that what we see is actual science or some touched up version of objects in our universe. p.s.: What st…

I am not doing astronomy but Photoshop is useful to analyze any kind of image. You can manipulate contrast, apply all sorts of filters, map a color palette, etc... All that using a user-friendly interface. It is very mature software used by millions of people, for general purpose image work, no custom tool will come close. I guess that scientists will also use specialized software for fine analysis, but it doesn't ma…

I'd recommend Fiji; it was developed within a scientific environment; and it is free (unlike PhotoShop).

Re: James Webb first images – complete set of high resolution shots now live

#274

Post by micromacrofoot »

historynops wrote: post #10

A lot of the pictures have some bright stars with 6 long lens flare like points coming out of them in a consistent pattern. Is that because of the hexagonal shape of JWT's lenses/mirrors?

Also, I recall reading that those stars are so bright because they're within our galaxy... so they're the foreground really

Re: James Webb first images – complete set of high resolution shots now live

#275

Post by djfobbz »

whiteboardr wrote: post #77

Watching the livestream i was more than surprised, that color correction actually happens in Photoshop. Also, there seem to be multiple layer-masks involved for specific regions and objects. I get that you can shift and composite color, based on hue, apply filters etc, but: Photoshop? Curious if anyone can explain, that what we see is actual science or some touched up version of objects in our universe. p.s.: What st…

I was wondering the same...why not also share the boring originals that we can process through our own filters?

Re: James Webb first images – complete set of high resolution shots now live

#276

Post by TheOtherHobbes »

april_22 wrote: post #184
throwaway09223 wrote: post #150

Earlier quoted context omitted.

No, there's none of that. These pictures aren't being used for any kind of science. They're 100% PR pieces, made to look pretty - which is fine!

Which makes me wonder how all these galaxies and nebulas would look like in real life. Would they look similar to how they colored it? Are those images maybe potraying a completely wrong reality?

There is no "in real life." The size, sensitivity, and spectral response of human eyes is a response to the radiation conditions on Earth, as enhanced by evolution.

If the Sun had been redder or bluer and your eyes were the size of your head or much smaller, everything would look very different.

The Webb images are infrared so "in real life" you'd never see them as shown here. You'd see whatever was visible in optical wavelengths.

This isn't just a quantitative difference. Those science fiction imagined alien worlds covered in little tiny technological lights - just like Earth - are a fantasy. Aliens might see UV instead of optical frequencies, and Earth would look like Venus to them - an opaque planet covered by a thick haze. They might light their spaces with UV, which we wouldn't be able to see so their planet would look dark to us.

And so on.

Re: James Webb first images – complete set of high resolution shots now live

#277

Post by pkaye »

anewpersonality wrote: post #30

Dumb question. Why can’t we focus on a single exoplanet, look for mountains, grass, buildings? Why am I so stupid but isn’t this the obvious thing to do?

How much details we can see if based on the wavelength of light and the diameter of the telescope. And if you worked it out, the telescope diameter would have to be enormous.

https://calculator.academy/diffraction-limit-calculator/#f1p...

However gravity can bend light so there is some thought of using the sun as a lens. However the observation would have to be pretty far away from our sun so its just wishful thinking in our lifetime.

https://www.freethink.com/space/gravity-telescope

For now the best we will have to see a dot on image via coronagraphy and maybe understand more about the exoplanet through spectroscopy.

Re: James Webb first images – complete set of high resolution shots now live

#278

Post by leeoniya »

sbierwagen wrote: post #266
leeoniya wrote: post #261

Earlier quoted context omitted.

> So about a tenth of the width of the moon. this is so much more digestible than "grain of sand at arm's length", and those two metrics dont feel at all equivalent -- the moon is not ten grains of sand at arm's length wide, right?

The moon is pretty darn small. Half a degree wide. Imagine gluing ten grains of sand together, balancing it on a fingertip, then stretching your arm out. Around a degree wide? Depending on your grain of sand, of course.

hmmm, about the size of an asprin tablet or pea at arm's length, seems to agree with somewhat smaller than thumbnail [1]. maybe i should find and measure some sand now :).

in either case, 1/10 the width of the moon is so much easier to comprehend. when is the last time anyone tried holding a grain of sand at arms length? what a weird comparison to make when everyone on earth already has a stable/familiar reference in the sky.

[1] https://astronomy.com/magazine/stephen-omeara/2010/01/stephe...

Re: James Webb first images – complete set of high resolution shots now live

#279

Post by sbierwagen »

moffkalast wrote: post #125
rbliss wrote: post #29

Earlier quoted context omitted.

Yes, it's a combination of both the primary mirror and struts. The JWST website has a very helpful infographic explaining: https://webbtelescope.org/contents/media/images/01G529MX46J7...

That's quite exhaustive, but it makes me wonder why isn't anything done to correct for that. Like for example instead of taking one 15h exposure, why not take three 5h exposures and roll the telescope 5 degrees in between, then median filter out the artefacts?

JWST does have a roll dither mode: https://jwst-docs.stsci.edu/jwst-general-support/jwst-dither... Don't know why they didn't use it. Maybe they were trying to observe as many targets as possible for the initial release of imagery.

Re: James Webb first images – complete set of high resolution shots now live

#280

Post by [deleted] »

Wowfunhappy wrote: post #183
roywiggins wrote: post #85

Earlier quoted context omitted.

Webb's primary camera is infrared, so there is by necessity a choice to be made with how to present the data for humans who can't see in infrared.

But, the inferred data is supposed to help us determine what I might see if I could teleport there (and time travel, not die, etc)—right?

[deleted]
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