to add to my LOL contribution - allow me to offer a positive afformation of the removal of stars.
It seems to me that any astronomical object has amazing depths. Depending on the FL, F ratio, FOV, length of exposure, filter usage, and astrophotographer, and many other variables, an individual object can look drastically different (consider radio vs optical). In my opinion this jsut adds to the wonder of the object and creatve license of the users. One can collect a multi faceted picture(s) of one object and only really start to appreciate its awsome depth. The removing of stars from an image is an attempt to highlight nebulosity, once again casting a different, but not necessarily an inaccurate, view of the object.
Apart from that it gives me something to do when its cloudy!
It works for some pictures where there's a lot of nebulosity and a very rich overwhelming start field such as Eta for instance. Other IMO don't work. M42 needs stars.
Is the removal of stars any different to 'imaging' in non-visual parts of the spectrum from a science point of view? We have all seen the resultant images which show different details of an object which are not otherwise visible.
Is the removal of stars any different to 'imaging' in non-visual parts of the spectrum from a science point of view? We have all seen the resultant images which show different details of an object which are not otherwise visible.
Yes it is.
If you image at radio frequencies for example, you don't remove part of the image that is being produced at the same frequency with a photoshop technique. Some stars will produce radio frequencies and will show up in the final image.
I must admit I don't like the photoshopped images with no stars. They look like nice artworks but could as easily be made with a paint brush on canvas and be just as relevant as astro images.
Why not add in areas of red nebulocity to a globular cluster to "enhance" it?
Not really any different to removing bits of image to enhance it.
Each to their own I suppose.
Some images do look better with less stars or with some reflector stars (not artificially put in with ps).
Wide field images can be overwhelmed with stars and if you take out some stars, it will make the image more balanced.
Non wide field images have (most times) not many stars and look very natural.
Yes it is.
If you image at radio frequencies for example, you don't remove part of the image that is being produced at the same frequency with a photoshop technique.
But the image is manipulated to assign false colour so we can see it at all.
Quote:
Originally Posted by Terry B
I must admit I don't like the photoshopped images with no stars. They look like nice artworks but could as easily be made with a paint brush on canvas and be just as relevant as astro images.
Why not add in areas of red nebulocity to a globular cluster to "enhance" it?
Not really any different to removing bits of image to enhance it.
Given the amount of post processing required to produce any image it could be said that they could all be produced without ever using a telescope of camera.
I think it is quite valid to remove stars which are not part of the subject but are in front of it from our line of sight.
Quote:
Originally Posted by Terry B
Each to their own I suppose.
Removing stars from a subject which has them is personal taste, and IMO the absence of stars can allow the image to show structure which is hidden. I would prefer to see both images side by side for comparison.
Last edited by michaellxv; 06-01-2010 at 03:10 PM.
Reason: spelling
But the image is manipulated to assign false colour so we can see it at all.
Removing stars from a subject which has them is personal taste, and IMO the absence of stars can allow the image to show structure which is hidden. I would prefer to see both images side by side for comparison.
I'm not sure how the stars hide anything. If you remove the stars you have to fill in the gaps with something. This is just false data created by averaging the adjacent pixels. It doesn't reveal anything behind the stars as the data is created in the imaging process.
False colour is added when imaging at non visual frequencies. It is added evenly though. It is not fabricated by averaging nearby pixels.
For example a star image will have the "red" colour of a nebula in it's continuum. To remove the star you have to remove that red part as well and then clone data back into the hole that is created. It just means that a large amount of the data in an image with the stars removed is fabricated data. Not dissimilar to painting a picture Over a photo.
I would rather see side by side images taken at different frequencies ie optical IR, UV, radio etc.
Having said this the starless lmages are still pretty pics but nothing much more.
But the image is manipulated to assign false colour so we can see it at all.
Stretching, colour assignment / balancing and enhancing the data to expose the elements of a subject is called image processing - you're not adding or subtracting real objects from the image (if you do it properly).
Quote:
Originally Posted by michaellxv
Given the amount of post processing required to produce any image it could be said that they could all be produced without ever using a telescope of camera.
Nonsense, that would be a painting.
Quote:
Originally Posted by michaellxv
I think it is quite valid to remove stars which are not part of the subject but are in front of it from our line of sight.
Almost a valid point , but you can't do that without altering the subject. You don't know what's hiding behind the stars so using PS filters and the clone tool changes the subject. I.e., it's not real. The more stars you remove the less real the image is and the more arty it is.
Quote:
Originally Posted by michaellxv
Removing stars from a subject which has them is personal taste, and IMO the absence of stars can allow the image to show structure which is hidden. I would prefer to see both images side by side for comparison.
Yes, it is personal taste thing, but NO you can't expose what's behind the stars cause you don't know what's there!!
Maybe it's just the scientist in me , but knowingly subtracting real elements of the subject (ie whatever is in the field of view) is fudging the data and belongs in the realm of make believe and pure art. The objective of a good image processor is to render the subject as strikingly as possible while keeping it as real as possible.
I agree. Wholeheartedly. Its just not SCIENTIFIC to nuke the stars.
I think agree.....
Actually....Fred's APOD M8 was just so good, I'm not sure I do agree now. I know! - you shouldn't be allowed to do it, unless you're Fred.......
(or Jase - he had something to do with that one too I believe)
, but you can't do that without altering the subject. You don't know what's hiding behind the stars so using PS filters and the clone tool changes the subject. I.e., it's not real. The more stars you remove the less real the image is and the more arty it is.
, but knowingly subtracting real elements of the subject (ie whatever is in the field of view) is fudging the data and belongs in the realm of make believe and pure art. The objective of a good image processor is to render the subject as strikingly as possible while keeping it as real as possible.
