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Watching the livestream i was more than surprised, that color correction actually happens in Photoshop. Also, there seem to be multiple layer-masks involved fo
by whiteboardr 4y ago
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 struck me the most is the absence of noise, especially for the deep field photo. Hubble took many exposures over weeks, which normally would allow for reliable reduction of noise, webb took some shots over the course of hours and there’s hardly any noise to see. Weirdest part is seeing them just “healing brushing” away some dots - how is the decision process on altering images like that?
(edit for typos)
- roywiggins 4y agoWebb'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.
- whiteboardr 4y agoI 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.
- DiogenesKynikos 4y agoAny real science will be done on the raw images, not on the color composites released for the public. These color composite images really show off how awesome JWST is. They're meant for the public to enjoy (astronomers enjoy them too).
- vishnugupta 4y agoThe person seen photoshopping very briefly talked about how he picks different colours for different region/light-frequency. But yes, more details will definitely be helpful. Also I guess they could open-source the untouched photos for other artists and photoshop experts to play around?
- empyrrhicist 4y agoThey aren't "untouched photos" in any traditional sense, but rather raw data. To visualize astronomical phenomena always requires processing/compositing. For that matter, traditional cameras on earth automate many of the same tasks being done here in Photoshop via debayering.
- roywiggins 4y agoThey did with Hubble: https://hla.stsci.edu/ https://hla.stsci.edu/ This article goes through processing a Hubble image of one of the same objects that Webb did today and includes an example of what it looks like before adjusting for contrast and tone. https://www.rocketstem.org/2015/04/20/how-astronomers-process-hubble-images-from-black-and-white-into-stunning-full-color/ https://www.rocketstem.org/2015/04/20/how-astronomers-proces...
- dguest 4y agoEverything will be public eventually. There's a bit on the data policy on wikipedia [1] but basically the operations costs are funded (in part) by people paying for telescope time. The project that is currently paying for the telescope gets exclusive access for a 1 year "embargo" period, after which the data becomes public. [1]: https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Ground_support_and_operations https://en.wikipedia.org/wiki/James_Webb_Space_Telescope#Gro...
- wthomp 4y agoSmall correction, no one will be able to pay for time on JWST. But if you put in a proposal for time and it's accepted, they will pay you. That's to make sure there is sufficient funds available to properly make use of the data you proposed for.
- dguest 4y agoActually that's sort of a large correction, thanks for pointing that out. Isn't it a bit of an inversion of the norm in astrophysics? I'd thought many grants included money for telescope time.
- mrandish 4y agoWhile Photoshop is widely used in artistic and creative imaging, it also contains a powerful suite of tools for image processing in arbitrary color spaces. I'm not even a serious user and across various hobby projects I've used it for stuff like manipulating 3D depth data and deriving logical bit masks. Photoshop can do just about anything with spatial image data and if it's not built-in, you can probably find a plug-in to do what you want or write a script. The trade-off is the software can be very complex because over the decades it's grown to support an incredible number of use cases. Over the years I've also seen PS used in unexpected ways at work. If you need to do something programmatic to image or spatial data, PS is a good host platform for custom code because it will handle importing file formats, color space conversion, bit plane manipulation, alignment, scaling, cropping, perspective correction and masking before your custom processing and then it'll export the output in whatever sizes and formats you need. And it will do it on gigapixel data sets under script control. That's a lot of grunt work you don't have to implement. I've even seen it wired up to Matlab.
- irrational 4y agoWhat tool would you expect them to use instead of Photoshop?
- tsbertalan 4y agoNumPy 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.
- ramraj07 4y agoNot just in astronomy but also in biology, pretty much anyone working with images uses photoshop at least for the final layout. In biology where the rgb overlay is paramount for result interpretation, generally it’s frowned upon to play with channels too much. But when you have 10k x 5k pixel images and channels that don’t directly correlate with visual spectrum I don’t see why using photoshop extensively is wrong especially for images to be released to the general public. I’m even sure some local touch up is acceptable for me.
- micromacrofoot 4y agoPhotoshop is actually more complex than the JWST itself. What makes it "unscientific"? The fact that it's a consumer product?
- deleted 4y ago[deleted]
- shitpostbot 4y agoI had always assumed they were doing it completely mathematically though. Like collating spectrometry readings to know what elements were present where and figuring out the temperature for blackbody emission or something, or even just linearly transforming the raw data from the spectrum the telescope can receive to the visible spectrum. Kinda disappointing if it's really just a paint by numbers Photoshop to look nice
- bowsamic 4y agoNo it’s done by hand with artistic license
- roywiggins 4y agoTerrestrial cameras don't behave that way. They apply tone curves from the beginning. They have to pick a white balance. They have to cram an HDR signal into an 8-bit image. They have to decide exactly how to process the color- every film stock and digital camera renders color a bit differently, even when ones that are all trying to produce true-color images and there are humans around who can compare it with their own subjective perceptions. The simplest, linearest way to do it is probably wrong, due to mismatches between human color perception and the camera's sensor / film stock. Eg, human rods and cones almost certainly don't have the same frequency response as the color filters inside your camera, and that's just the beginning. Anyway, this post shows an example comparing a "flat" color composite and one that's been tonemapped etc. This is using Hubble data but it's the same subject as one of the JWST images. https://www.rocketstem.org/2015/04/20/how-astronomers-process-hubble-images-from-black-and-white-into-stunning-full-color/ https://www.rocketstem.org/2015/04/20/how-astronomers-proces... This video goes into some detail about the filters that were used for one of these JWST images: https://www.youtube.com/watch?v=zAbI8bux-jM https://www.youtube.com/watch?v=zAbI8bux-jM
- Wowfunhappy 4y agoBut, 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 4y ago[deleted]
- empyrrhicist 4y agoYou'd have a tough time defining "there" in images like this, and your eyes are not evolved to see faint, diffuse, glowing gas structures in the infrared.
- moffkalast 4y agoI think you've answered your own question there, it's just PR images touched up by the media team without regard for anything. If there's any science being done it'll be done by matlab scripts using raw data as input.
- jacquesm 4y agoThe difference between 'actual science' and 'some touched up version of objects in our universe' is smaller than you might think: no matter how good your eyes, if there was no frequency shift involved you would not be able to perceive the image, other than as an array of numbers. To facilitate your consumption of the data it has to be frequency shifted and the easiest way to do this is to map the IR intensity to a range of colors that are graded the same way we grade false color images from other sources: higher intensities get brighter colors and lower intensities darker colors. Because not all of these are equally pleasing to the eye and/or enlightening Photoshop is actually a pretty good choice because it allows for dynamic experimentation what brings out the various details in the best way. If you would rather stare at an array of numbers or a non colorized version (black-and-white) it would be much harder to make out the various features. So think of it as a visual aid, rather than an arts project or a way to falsify the data: the colorization is part of the science, specifically: how to present the data best.
- ricardobeat 4y agoWhat would these look like, if you could point a ground telescope at the exact same spot? How much light is in the visible spectrum?
- JacobThreeThree 4y agoHere's a Hubble-based nebula that was imaged in both infrared and visible. https://esahubble.org/images/heic1406c/ https://esahubble.org/images/heic1406c/
- whiteboardr 4y ago
- bottled_poe 4y agoI’m confused.. why would we expect some other image processing software to be better than Photoshop - a software package which has been the top of its class for ~30 years?
- deleted 4y ago[deleted]
- yread 4y agoCan it even open FITS?
- clint 4y agoYes. https://esahubble.org/projects/fits_liberator/download_v23/ https://esahubble.org/projects/fits_liberator/download_v23/
- randyrand 4y agoBecause photoshop it not open source, not verifiable, and not documented on a scientific level about how its filters behave.
- Hadriel 4y agoEh, it's been pretty tested. Any person can easily apply filters and verify the change in image properties and see how filters behave.
- c048 4y agoWhy would they worry about that? These colored images aren't used for science, they're meant for marketing.
- ashes-of-sol 4y ago
- MAGZine 4y agoThey're not doing science with photoshop. They're creating assets for consumption by the public.
- GuB-42 4y agoI 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 make Photoshop useless.
- amelius 4y agoI'd recommend Fiji; it was developed within a scientific environment; and it is free (unlike PhotoShop).
- dmead 4y agoamateur astronomer here. (https://www.instagram.com/mead_observatory/ https://www.instagram.com/mead_observatory/) 1. photoshop is really good at composing different (spectral) layers together. There is alternatives to this like pixinight that are more geared toward deep sky astronomy work but I'm sure it's easier to hire people that can just take a Photoshop class. there are many layers/masks involved for different filters. the filters accept or reject certain wavelengths of light and may be designed for specific elements on the periodic table. people often talk about hydrogen filters or oxygen filters, sulfer filters etc. the color distinction you see is actually indicating elemental composition much of the time. I'm not sure what filters webb is using. 2. modern telescopes clean up their images by taking a "master dark frame" that is a stacked frame of many frames taken with the lens cap on. The goal there is to compute the noise profile of the sensor. I'm sure before launch the darks for the sensors were determined and are at the ready to correct and calibrate images coming from the telescope. think of it as applying a bespoke noise filter for that sensor. It's a fast process to apply it, but not to generate it. If they really make the raws available I'm sure we'll see more noise there. 3. the touch up you see them doing is the removal of a hot pixel which survived the calibration process with the dark frame. no doubt on space telescopes they still get errant hot pixel of some kind of particle or cosmic ray they don't want makes it to the sensor and flips a bit (and is therefore not account for in the master dark). happens all the time. they're probably keeping a map of where they're getting hot pixels.
- willis936 4y agoThanks for 3. Without the explanation it really did come off as doctoring data to be more artistic.
- dmead 4y agoBut they are doctoring it to make it more artistic/presentable. I have no doubt that real astronomy presentations/papers want to see the undoctored data at some point. Did you mean you thought they were adjusting the content and not just fixing noise?
- buildbot 4y ago
- yread 4y agoI would have expected ImageJ has plugins better suited to work on science
- deanCommie 4y ago> actual science or some touched up version of objects in our universe. Here's a mental model that I found particularly beneficial: All electromagnetic radiation is the same. In the sense that every proton/neutron is the same. But adding a few more protons/neutrons creates an entirely new element, with entirely new chemical properties. From something simple come incredibly new powerful behaviours. So just as Iron is massively different from Plutonium, Microwaves are massively different from Gamma rays. What we call "visible light" is not particularly special, except to us, and our specific human biology. It feels more real because it's visible to us, but it's not on the grand scale of the universe. What we're observing through these telescopes isn't a dog chasing a ball. We're seeing stuff billions of light years away, millions of light years in size, billions of years ago. Passing by trillions of other stars and planets on the way. These objects are emitting a gargantuan amount of information. Why should we only present the information that happens to be in the same subset as what our primitive primate vision cones can process? So, no, if you were to teleport to the nebula/galaxy that we're showing images for, it wouldn't look exactly like that to your human eyes. Instead, what you're seeing is what a god with perfect vision of the universe would see. You're seeing the universe for what it is, not just the part of it that is presented to humans.
- penneyd 4y agoVery nicely stated.
- djfobbz 4y agoI was wondering the same...why not also share the boring originals that we can process through our own filters?
- _justinfunk 4y agohttps://mast.stsci.edu/api/v0/index.html https://mast.stsci.edu/api/v0/index.html Here's the API to access the boring original data.
- beowulfey 4y agoI work with images on the other end of the scale regularly, and amongst scientists it's probably 50:50 Photoshop or ImageJ for editing images like that.
- Paddywack 4y agoI read a detailed interview with the person who does the enhancements a couple of days ago (can’t recall where a grrr). He said: A) there are two of them in the team doing the imaging B) it doesn’t start with an image - it’s literally heaps of binary data that the scientists stitch together C) he then does the colour overlay based on agreed norms (one colour per input frequency for consistency) D) most of his “touch up” work is getting the colour gradient right between the brightest and dimmer objects - without this a lot of resolution would be lost (brights too bright, or dim not visible). Hope this helps…
- supernovae 4y agoI use PixInsight myself, but you can do a lot on photoshop and a lot of people will take the output of PixInsight to touch up in photoshop. Modern sensors are amazingly low noise. 10 years ago, I used to have to calibrate out darks, bias and flats just to remove my sensor noise. Now with modern CMOS sensors, people still do that but it isn't as necessary and you can overcome much of the sensor noise by capturing enough data - and that's where JWST just dominates. THere is nothing impeeding the data causing noise. Shot noise is easily removed by integration, Read noise on modern sensors is almost non existent and easily calibrated out, dark current is extremely low, bias, hot and cold pixels are all things that can be removed with calibration and integration and with space telescopes cosmic rays are probably the most annoying thing but if you stack enough images they integrate right out. But back to photoshop, the final images are just publishing art. I use pixinsight myself for all the heavy lifting, pixel math, integration and calibration but sometimes go out to photoshop for cleanup - especially for web/print.