Hello, this is my first post here. I hope someone can shed some insight into something I noticed when dropping hubble photos into photoshop.
Take almost any high quaity photo that has a lot of black space in it, the ones I found to work best are a galaxy in the center of the image.
play with the gain in Photoshop. (I also play with curves to invery the white end, making the white centers looking more like the black holes that are underneath)
When playing with the gain, the black regions should show a series of many parallel lines on a curve. These lines distort when close to large objects.
What could these lines be? They look like ripples in water.
Camera distortion?
An insanely long wavelength form of energy?
aftermath of distant supernova?
I just thought of something, it's probably magnetic waves.
Sounds like JPEG artifacts if you aren't working with the originals. Sounds like instrument or processing artifacts if you are working with the original TIFFs.
JPEG artifacts are natural for very dark fields because JPEG will tend to preserve tiny gradients in brightness, even in the absence of an actual signal.
JPEG artifacts are natural for very dark fields because JPEG will tend to preserve tiny gradients in brightness, even in the absence of an actual signal.
I'm a multimedia designer, among other things. I made sure it wasn't banding, and used the tiff's. I could provide the files if you want, but don't see an upload function here. I have a home server, however.
This forum has never had an upload function.
But even the TIFF's aren't raw data.
But even the TIFF's aren't raw data.
Ok I have them uploaded, have a look.
In example 1 I drew with the mouse where I see the lines.
This forum wont let me post a link... so you'll have to re-build it.
ubuntu[]starkcraft[]com/hubble/example_1.psd
ubuntu[]starkcraft[]com/hubble/example_2.psd
Thank you for your time.
In example 1 I drew with the mouse where I see the lines.
This forum wont let me post a link... so you'll have to re-build it.
ubuntu[]starkcraft[]com/hubble/example_1.psd
ubuntu[]starkcraft[]com/hubble/example_2.psd
Thank you for your time.
The images you provided are very small versions of the full sized versions which IIRC are generally available on most NASA sites as well as the STSCI site, I have downloaded 300meg images many times... 9.5 megs is nothing really.
And since I don't see it mentioned above ... many images from STSCI are "composites". ANY composite image is going to have some little artifacts that you can find playing around in photoshop.
The thing that should occur to you is that the researchers using the raw data from Hubble observations are typically going to be "all over" any unexpected variable that shows up in the imagery. It's what astronomer do for a living.
So ... what I'm saying is ... you noticing something means nothing really. You're not finding something that nobody else has seen and accounted for scientifically.
And since I don't see it mentioned above ... many images from STSCI are "composites". ANY composite image is going to have some little artifacts that you can find playing around in photoshop.
The thing that should occur to you is that the researchers using the raw data from Hubble observations are typically going to be "all over" any unexpected variable that shows up in the imagery. It's what astronomer do for a living.
So ... what I'm saying is ... you noticing something means nothing really. You're not finding something that nobody else has seen and accounted for scientifically.
you haven't explained why this is happening. it's not the image compression.
Do you have the 300meg version I could play with?
I'm not trying to say it's something 'new', just a proper explanation.
Do you have the 300meg version I could play with?
I'm not trying to say it's something 'new', just a proper explanation.
It's a Moire pattern stemming from the grinding pattern of the lens and the 'pattern' of the stars.
I can see how a Moire pattern could explain this.
What I can not see is how the pattern of the stars have anything to do with a moire pattern effect, as a star pattern is far from uniform, where this effect is. Is there some other element other than the stars here, like gama radiation, magnetism or something else that could cause the cosmic dust to form a real pattern that could cause this?
It could actually be downsampling, so I'd like to find the original images. It is less likely downsampling with Tiff's, however.
I find this fascinating if it has to do with a natural phenomena, even being a moire pattern.
What I can not see is how the pattern of the stars have anything to do with a moire pattern effect, as a star pattern is far from uniform, where this effect is. Is there some other element other than the stars here, like gama radiation, magnetism or something else that could cause the cosmic dust to form a real pattern that could cause this?
It could actually be downsampling, so I'd like to find the original images. It is less likely downsampling with Tiff's, however.
I find this fascinating if it has to do with a natural phenomena, even being a moire pattern.
QUOTE (sstark+Oct 26 2009, 10:16 PM)
I can see how a Moire pattern could explain this.
What I can not see is how the pattern of the stars have anything to do with a moire pattern effect, as a star pattern is far from uniform, where this effect is. Is there some other element other than the stars here, like gama radiation, magnetism or something else that could cause the cosmic dust to form a real pattern that could cause this?
The stars are of course, not uniform. I enclosed the word 'pattern' in quotes when referring to the stars for that reason. However, there's enough of them that the distribution of stars over almost any sized square of the image is pretty uniform. The unevenness of the stars in the image actually evinces the idea of it being a Moire pattern, because it explains why the pattern itself is not uniform over the extents of the image.
After looking up some specs on the telescope's mirrors, I'm starting to think this might be an equally viable or more viable explanation. The mirrors are polished to 1/10th the wavelength of visible light, meaning they should not contribute to a Moire pattern in any image taken using visible light. However, if this is a composite image including infrared (which the Hubble is notoriously bad at, but not incapable of as far as I know) then my initial guess might be right.
I'm as close to 100% certain that it is a Moire pattern as I can be, though. It is exactly what I'd expect to see from one in which one of the contributing 'patterns' is something as random, yet uniform as the distribution of stars in this picture.
Alternately, one of the contributing factors might be reflected light from the Earth, Moon or some part of the telescope itself. It does seem to emanate from the middle right of the image to a certain degree, and many objects can produce a pattern in the light they reflect, thanks to texture or interference patterns.
EDIT: I've thought of something that lends more credence to your idea about it being a product of downsampling. A few years ago, I got a hold of some software used to display wideband (infrared, visible band and ultraviolet) images, and some images to go along with them. The software, though very high end, had no export feature. The only way to export the images into a more common format was to zoom extents and take a screen capture (or zoom in and take multiple captures to splice back together). I remember noticing that one zoomed out image had a Moire pattern in the part of it which displayed a chain link fence. I think it's quite likely that the raw Hubble images might have 5 or more channels per pixel, which might indicate that the images you're working with could have been produced the way I just described.
What I can not see is how the pattern of the stars have anything to do with a moire pattern effect, as a star pattern is far from uniform, where this effect is. Is there some other element other than the stars here, like gama radiation, magnetism or something else that could cause the cosmic dust to form a real pattern that could cause this?
The stars are of course, not uniform. I enclosed the word 'pattern' in quotes when referring to the stars for that reason. However, there's enough of them that the distribution of stars over almost any sized square of the image is pretty uniform. The unevenness of the stars in the image actually evinces the idea of it being a Moire pattern, because it explains why the pattern itself is not uniform over the extents of the image.
QUOTE
It could actually be downsampling, so I'd like to find the original images. It is less likely downsampling with Tiff's, however.
Depends on the method used. There are a few methods of downsampling which could produce a Moire pattern. After looking up some specs on the telescope's mirrors, I'm starting to think this might be an equally viable or more viable explanation. The mirrors are polished to 1/10th the wavelength of visible light, meaning they should not contribute to a Moire pattern in any image taken using visible light. However, if this is a composite image including infrared (which the Hubble is notoriously bad at, but not incapable of as far as I know) then my initial guess might be right.
I'm as close to 100% certain that it is a Moire pattern as I can be, though. It is exactly what I'd expect to see from one in which one of the contributing 'patterns' is something as random, yet uniform as the distribution of stars in this picture.
Alternately, one of the contributing factors might be reflected light from the Earth, Moon or some part of the telescope itself. It does seem to emanate from the middle right of the image to a certain degree, and many objects can produce a pattern in the light they reflect, thanks to texture or interference patterns.
EDIT: I've thought of something that lends more credence to your idea about it being a product of downsampling. A few years ago, I got a hold of some software used to display wideband (infrared, visible band and ultraviolet) images, and some images to go along with them. The software, though very high end, had no export feature. The only way to export the images into a more common format was to zoom extents and take a screen capture (or zoom in and take multiple captures to splice back together). I remember noticing that one zoomed out image had a Moire pattern in the part of it which displayed a chain link fence. I think it's quite likely that the raw Hubble images might have 5 or more channels per pixel, which might indicate that the images you're working with could have been produced the way I just described.
thank you for your detailed response. Very interesting! Especially the part about reflected light causing the effect, and the lens's size.
All that's left to do is hunt for the originals... anyone know where they might exist? This was the largest I saw on the NASA site, but I was looking in the gallery. Is there another resource available to get the original raw image data?
All that's left to do is hunt for the originals... anyone know where they might exist? This was the largest I saw on the NASA site, but I was looking in the gallery. Is there another resource available to get the original raw image data?
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