Imaging 'accuracy' question

[pevsfreedom]

I've been browsing the imaging sub forum a lot on here and the pictures are absolutely astounding,

What's also astounding is the amount of editing/remastering/filters/etc. these pictures require. 

How 'true' are these images? Is this kind of like taking my ugly mug and turning me into Kim Kardashian for a magazine cover (ok bad example) or is it just a method of fighting the light years of distance to get some color to the photo's. The photo's are pretty amazing, but isn't it 'cheating' once you start adjusting colors in photoshop, etc. (as far as 'reality' goes?). Are the colored images 'realistic', or is there no way to tell? Are the monochrome photo's more realistic? 

Just curious.

[carastro]

You don't physically change the images, you just "drag out" what is buried in the darkness.  

Carole 

[pevsfreedom]

You don't physically change the images, you just "drag out" what is buried in the darkness.  

Carole 

That's what I was trying to confirm Thanks. 

[redmoo]

I've been browsing the imaging sub forum a lot on here and the pictures are absolutely astounding,

What's also astounding is the amount of editing/remastering/filters/etc. these pictures require. 

How 'true' are these images? Is this kind of like taking my ugly mug and turning me into Kim Kardashian for a magazine cover (ok bad example) or is it just a method of fighting the light years of distance to get some color to the photo's. The photo's are pretty amazing, but isn't it 'cheating' once you start adjusting colors in photoshop, etc. (as far as 'reality' goes?). Are the colored images 'realistic', or is there no way to tell? Are the monochrome photo's more realistic? 

Just curious.

I think most people try and stay true to the colours that actually exist. Sure, you have light polltution filters etc, but most of the processing in PS is to try and get the colours back to where they were. 

One major exception to this is the narrowband images that you see, where each colour represents a different 'gas'.

I mean, you could look at it that all the pictures taken on earth aren't really 'true' colours, as the lighting around them makes a huge difference (just look at the blue/black or white/gold dress thing that has been going around as of late).

Are monochrome images more realistic? I guess that would depend on your target!

Anyway, so long as it looks good!

[johnrt]

There are 2 types of colour images presented by astrophotographers - false colcour narrowband images and RGB (red, green, blue). The RGB images are exactly as a normal daylight photograph, each colour is captured with the corrisponding filter and applied to the correct colour in the editing software of choice. No trickery with colours. RGB images are suitable for galaxy, reflection and emission nebula along with clouds of molecular dust and perhaps star clusters globular or open.

Seceondly are narrowband false colour images. Narrowband filters map the distribution of gasses emitting light at a specific wavelength. It is then down to the imager to present those gasses in a colour palette that pleases them. A very different type of image altogether. Narrowband images are of planetary and emission nebula.

Neither type of image is wrong, they simply show different types targets presented in different ways.

[pevsfreedom]

I think most people try and stay true to the colours that actually exist. Sure, you have light polltution filters etc, but most of the processing in PS is to try and get the colours back to where they were. 

One major exception to this is the narrowband images that you see, where each colour represents a different 'gas'.

I mean, you could look at it that all the pictures taken on earth aren't really 'true' colours, as the lighting around them makes a huge difference (just look at the blue/black or white/gold dress thing that has been going around as of late).

Are monochrome images more realistic? I guess that would depend on your target!

Anyway, so long as it looks good!

Interesting point as well. Who knows what 'true' colors are anyway... human eye/perception is very limited in that regard. 

[pevsfreedom]

There are 2 types of colour images presented by astrophotographers - false colcour narrowband images and RGB (red, green, blue). The RGB images are exactly as a normal daylight photograph, each colour is captured with the corrisponding filter and applied to the correct colour in the editing software of choice. No trickery with colours. RGB images are suitable for galaxy, reflection and emission nebula along with clouds of molecular dust and perhaps star clusters globular or open.

Seceondly are narrowband false colour images. Narrowband filters map the distribution of gasses emitting light at a specific wavelength. It is then down to the imager to present those gasses in a colour palette that pleases them. I very different type of image altogether. Narrowband images are of planetary and emission nebula.

Neither type of image is wrong, they simply show different types targets presented in different ways.

Makes sense. I was wondering if that's how it worked or if it was simply 'adding' color, the 'real' method is much more sincere. 

[Scorpius]

I've been browsing the imaging sub forum a lot on here and the pictures are absolutely astounding,

What's also astounding is the amount of editing/remastering/filters/etc. these pictures require. 

How 'true' are these images? Is this kind of like taking my ugly mug and turning me into Kim Kardashian for a magazine cover (ok bad example) or is it just a method of fighting the light years of distance to get some color to the photo's. The photo's are pretty amazing, but isn't it 'cheating' once you start adjusting colors in photoshop, etc. (as far as 'reality' goes?). Are the colored images 'realistic', or is there no way to tell? Are the monochrome photo's more realistic? 

Just curious.

Interesting question and a great explanation can be read by clicking here: http://www.astropix.com/HTML/I_ASTROP/COLOR.HTM However, it would seem that image accuracy would also depend on the level of detail - not just color. I think it's safe to say that utilizing software to pull every bit of detail possible out of the data you capture is perfectly acceptable but adding detail not present in the original data would be considered a faked image.

Another point to consider is even the Hubble produces images in "false color" - the Hubble pallet as it's called, is very similar (if not the same) as the narrowband images you see on this forum and elsewhere. So I would say color in astronomical images is sort of like the old saying "beauty is in the eye of the beholder" (or the imager in this case) but the detail is either there or it's not - and that depends on the quality of data captured and the individual's experience with processing that data. More than once, I've seen experienced members of SGL download a photo posted by a beginner, then work a little processing magic on it, then repost it in an effort to help the original author improve their processing skills and show the data's full potential. Oftentimes this results in a second image that's hard to believe was produced by just tweaking the data in the first image. In this case, was the first image "real" and the second one "fake"? Of course not, the second image includes more detail due to better processing skills but this could not be accomplished with software unless that higher level of detail was a true characteristic of the object. So in that sense, the most realistic images are the ones that represent the most detail present in a given object.

This may not be a "totally accurate" explanation but it sounds good on paper... 

[pevsfreedom]

Makes perfect sense. I read (red) somewhere also that if you use a red filter, and there's no red in the object, you won't see any red. Made a lot more sense that way. 

[ollypenrice]

There is an entirely mistaken notion at large that, left to its own devices, a camera will somehow record 'the truth.' In fact no camera, left to its own devices, records anything at all.

In the days of film there were chemists brewing up emulsions and making decisions 'for the camera' in regard to response to different coloured light. Those were human decisions made in the lab. Those decisions then appear in the pictures taken with that film, controlling the colour balance.

Nowadays monochrome digital sensors (there are no other kind) record light filtered through red, green and blue filters and an awful lot of fancy software, in camera or out of camera, is used to interpolate the measurements made through the filters and turn them into a colour image. Again this all involves human intervention and decision making behind the scenes of the camera. 

In astronomy there is, in fact, less of this human intervention in monochrome luminance-red-green-blue imaging through separate filters than in one shot colour imaging. In the latter, software is needed to interpolate the continuity of shapes across the matrix of tiny RGGB filters on the chip. In LRGB imaging from mono cameras the luminance layer is inherently continuous and does not need to be synthesised.

The processing of images involves two main things, the removal of artefacts and the extraction of hidden information. This gets us closer to the truth than leaving an image unprocessed.

Olly

[wxsatuser]

The great photographers from the past like Ansel Adams would spend hours in the darkroom manipulating their images.

Astrophotographers are no different we just live in the digital age and extract our images in a more modern way.

[lensman57]

The great photographers from the past like Ansel Adams would spend hours in the darkroom manipulating their images.

Astrophotographers are no different we just live in the digital age and extract our images in a more modern way.

As a devotee of Adams, I always remember what he said about his negatives ( the data in digital terms ) that a negative is like a musical score but the photograph is the conductors interpretation of that score. For those who don't know Adams, he was originally trained as a classical pianist. I think that his statement hold true to this day.

A.G

[glowingturnip]

there's an anthropic reason too - because of the way our eyes work, the rods are most sensitive in dark conditions but don't have colour sensitivity, so when we look at the night sky, or at a fuzzy through a telescope, we see little if any colour. 

When we look at an astro photo, it is tempting to assume that the colours are fake since we can't see them, but actually what we are doing then is blaming a short-coming in our eyes on the photo - the colours are most definitely there since the cameras can see them, but its our eyes that give us the 'fake' view by only showing it to us in monochrome.  Imagine how amazing it would be if you could see the night sky in colour !

[Scorpius]

Makes perfect sense. I read (red) somewhere also that if you use a red filter, and there's no red in the object, you won't see any red. Made a lot more sense that way. 

Even if the color red is being emitted by an object and you image it through a red filter, you still won't "see any red" until you instruct the software to apply the data contained therein to the red channel of an RGB image. In other words - as pointed out by Olly above - no camera can apply color to an image since color balance is a function of the software used to process the data.

For example, if you insert the data normally associated with the red channel into the blue channel and insert the data associated with the blue channel into the red channel, the color red would appear blue and the color blue would appear red in the final image. Point is - all three colors associated with objects imaged through RGB filters are monochrome (B&W) until they are inserted into the correct color channel in the software. Difference with one shot color cameras is the software automatically inserts the data into the corresponding color channel without requiring input from the user. However, color cameras aren't as sensitive because if a green photon lands on a red filtered photosite, the color green associated with that photon will not be reproduced in the final image. Therefore, one shot color cameras are simply monochrome cameras with built in RGB filters but they don't capture as much color due to the fixed nature of their built-in, microscopic RGB filters.

[skysculptor]

Imagine how amazing it would be if you could see the night sky in colour !

We do see the sky in colour! It just depends on how bright the colour of the object is! For example Betelgeuse looks very red to the naked eye, other stars look clearly blue and a planet like Mars is clearly a red dot and thought a scope with a eyepiece Jupiter is very multi coloured stripes!

[laser_jock99]

The possible 'adjustments' with modern image editing software are seemingly endless and give the same starting image I could end up with a completly different looking end results on different days!

The reason for doing any editing at is that most RAW images look pretty dire straight from the camera and need some editing to make them vaguely presentable.

Are the images 'accurate'? Not really- most are edited to extract and enhance the faintest details and to surpress the bright information. The colours are often adusted to suit the imagers taste also.

If you end with a final image that you (and possibly a few others) are happy with, then that's what counts.

[kalasinman]

Photographers have always been caught on the horns of a dilemma. Is photography art or science? IMO the science is mostly done elsewhere and what is produced is mostly for human enjoyment.

[Carina Lass]

The measurement of light and suppression of stray light is all that is going on.

There's no faking it and there's no introduction of light that wasn't there.

How well that is done is another matter. ..

[KennySharp]

I'm a fan of using image processing only to enhance the astronomical data captured by the camera. Not adding to it. I've seen some YouTube videos on how to process the Orion nebula. They are very much worth watching but at some point they transition from enhancing astronomical (scientific) data to adding effects to make the picture 'prettier' (artistic). That's fine if you want to stick it in an art gallery. Don't do it if you want to post it in an astronomy forum. But where is the line between the two? That is very subjective.

[ollypenrice]

I'm a fan of using image processing only to enhance the astronomical data captured by the camera. Not adding to it. I've seen some YouTube videos on how to process the Orion nebula. They are very much worth watching but at some point they transition from enhancing astronomical (scientific) data to adding effects to make the picture 'prettier' (artistic). That's fine if you want to stick it in an art gallery. Don't do it if you want to post it in an astronomy forum. But where is the line between the two? That is very subjective.

Could you link to them?  I'm curious.

The Orion nebula is all about dynamic range. Now our eyes and ears (I don't know about our olfactory organs) already stretch and compress the signal they receive in order to cover a higher dynamic range than the raw signal would allow. We don't see or hear 'scientifically.' What we see and hear has been Photoshopped/'Audioshopped' by the brain.

A lot of what's interesting in AP is performing that process over again. It is not possible in a single exposure to capture the whole of the Orion Nebula without failing to capture the outer parts or burning the Trapezium region to white. So we take two or three sets of different length exposure so that each set can capture best what is really there at each exposure level. The trick is then to combine them as they might be seen by an eye-brain with the necessary dynamic range. Once every few years the poor imager thinks, I reckon I can do better than last time, and has a go. No sane imager thinks he or she will ever consider their M42 to be final. This is about my tenth effort and I hope to live long enough to try ten more! (Don't bet on it...  )

I'll be back... 

lly

[sgazer]

One way I just thought of looking at it in defense of one shot colour cameras, eg dslr, if one takes a daylight photo with certain settings that looks to me like the real thing (colour etc), then once pointed at the sky, with the same settings it should also capture what I'd see if my eyes were sensitive enough.