What's a natural looking image

[MartinB]

People often compliment an image for looking "natural". Over enthusiastic processing tends to produce an "unnatural" image with sharpening artefacts, burnt out areas and excessive contrast but apart from that what makes an image look natural? Since we hardly ever see any colour in DSOs are colour images natural or unnatural. Why is a hubble palate false colour image unnatural compared with an HaRGB which is equally beyond our experience.

If we looked up at the sky as seen through the scopes of Rob Gendler we would have a very weird psychadelic experience.

So what do people think of as natural and is natural a good thing when it comes to a deep sky image?

[Psychobilly]

I don't like images with jet black backgrounds and hard cut-off at the edges of nebulae, or taht have been overly processed to remove "noise" resulting in blured images...

I suppose we could argue that a natural looking image should be a grey amorphous blob showing no detailed structure...

Peter...

[Jamie]

I feel that a natural looking image is one where the colours are not too strong, the background is not too black, the edges are not too sharp..........Oh and that is doesn't look like it was processed by Hanna Barbera.....

In other wise not too perfect..... A big ask i know....

[barkis]

I know colour is used to enhance a deep sky image. The Orion Nebula for example through a large instrument, visually has a greenish bluish tint to it. This is a natural effect of red Hydrogen having lost energy due to the vast distance it has traversed. The same can be said for many other nebulae and galaxies.

Processing an image to faithfully reproduce the colours inherrent in the object, and all it contains, is not an easy interpretation to make, and therefore a lot of artistic licence is applied. I don't know if it is true to say that Narrowband Imaging is an easier, or more faithfull way to colour a particular DSO. It will take someone sharper than me to do that.

I don't know if I am qualified to any degree, to comment at all on this subject, but my reply is one of gut feeling, rather than knowledge.

Anyway, when I see a large Mono Image in it's varying shades of greyscale, I find it just as impressive as a North American Nebula in glorious colour for example. And may I say, Rog. has no infuence on my last sentence.

Ron.

[ashenlight]

This is an interesting discussion... personally, I think the best way to get a 'natural' looking representation of a space-bound object is to sketch it. Can only draw what the human eye can see that way, and is a good way for beginners to gauge what they can expect in this way I do prefer the natural looking photos/sketches from an observing point of view... no disappointment that way... but processing does seem to draw the best out of an image. Guess it's all down to personal taste!

Amanda

[MartinB]

For me, the more an image shows about the target the more I like it. That's why I like colour - blue areas of hot stars in the outer galaxy lanes, brown dust regions, red ha, teal OIII, blue reflection areas. This information doesn't come through with monochrome although mono, as far as astro goes, is really more natural. Narrowband can show more than LRGB so that is great in my book.

I still like images to look natural and not Hanna Barbera although there probably is a Tom and Jerry nebula out there somewhere!

I love sketches too, done well they give a great insight into what can be seen through the eyepiece by a careful observer.

[ashenlight]

Good point Martin, I guess colour can tell you more about a region - it's age, what kind of stars make up the population and so on.

Sketching has definitely made me a more 'observant observer' - it's amazing what jumps out at you the longer you look at a crater on the Moon for instance - delicate ridges, tiny tiny craters etc. Would definitely recommend it for someone wanting to increase their observing skills.

[Kai]

I suppose we could argue that a natural looking image should be a grey amorphous blob showing no detailed structure...

I knew that eventually people would come around to my level of processing

[Psychobilly]

ROFL Kai

Peter....

[MartinB]

I knew that eventually people would come around to my level of processing

[Whippy]

I've viewed my imaging as an extension to what I normally do as an observer so I aim for 'natural' look in that I try and keep the noise down to minimum, not to force the curves/levels too hard and not go mad on the sharpening. I guess the overall effect I aim for is to visualise what I would see through a very big scope! Of course adding colour makes for a more exciting, prettier picture but sometimes the drama of monochrome (especially on nebulae) suffices just fine.

That's my take on it anyway.

Tony..

[beamer3.6m]

I suppose a natural looking image would really be a sketch as these are usually more acurate as to what can actually be seen with the eyes or a scope.

However, I suppose that if the objects photographed are actually like seen by hubble then I suppose that is truly natural.

In essence a natural shot means one that looks as the eye would see the object.

[Psychobilly]

In essence a natural shot means one that looks as the eye would see the object.

Back to the faint grey fuzzy blob then ....

[beamer3.6m]

Back to the faint grey fuzzy blob then ....

Ahh but heres the question:

How would the eye see it if you were standing next to it. So if M42 looks like the hubble image if you were next to it (forget the size of it causing problems) then that would be the natural image. If however when you stood next to it it still just looks like a grey smudge then that would be the natural image.

At least that is what I think.

[Aza]

I guess for me it is an image that hasnt been over processed.

The more processing applied to it then less natural it becomes (I suppose!)

I have seen Rob make comments on the colours of his images, by saying its what was in the data, or something like that. So really letting the data show its true self without forcing it!

[MikeD]

For me a natural looking colour image is one that has not had the saturation pushed too far and any noise reduction is done by collecting more data instead of over using noise reduction software which IMO can make an image look very artificial.

Clipping of the data at either the black and/or white points is another way an image can look (to my eye) unnatural.

It's hard to pin down when an image starts to look unnatural but my rule of thumb is if it looks processed ( by looking at the image you can see the processing methods that have been used e.g clipping, smoothness due to over use of noise reduction and sharpening artefacts) you have gone too far.

It's better IMO to have less detail in image and keep a natural feel than to push the data for every last ounce of faint detail which will bring with it noise and the need for more processing and data repair and with that a less natural looking image.

If you want more detail and keep a natural looking result, you have to spend the extra time at the scope not the PC.

Mike.

[roundycat]

It all comes down to exposure in the end. Whether you expose the eye or film or a chip insufficient exposure will not let you see what is really there. The fact is that ionised gas does have a colour and it is the shortcomings in our vision that stop us from seeing it.

If you do a tri colour picture of an earthbound object and give it minimal processing it will come out in colour. You can adjust it to what you actually saw. The minimal processing bit is mentioned because if you expose a picture of a car in daylight or at dusk you will get a full (16bit) depth to the information. We don't get this with dso's, not because the info is not there but because the exposure is inadequate. It should come as no surprise that the likes of Gendler/Croman/Block get better pictures than the rest of us because a) they have big scopes up a mountain somewhere and because they seem to expose for 20 hours or so as a minimum.

The more you expose the less you need to stretch. Ergo, the info that is there will come out easily. Anyone can put this to the test with the Rosette, NA neb or M42, the brightest dso's in the sky. If you have the necessary depth of exposure you do not need to go in for GBH with Photoshop.

So, to answer the question. for my money you apply minimum processing for a natural look. No more than you would need to do for the car at dusk. But first get the exposure.

Dennis

[FLO]

For me 'natural' is when you notice the subject itself over and above the actual 'image' and its processing. A bit like quality hifi where the sound is so pure and natural that you don't notice the equipment playing it.