thoughts ......
Depends whether you want to do art or photography, there’s been a few images that I felt fall into the Astro art with a camera category, rather than “astrophotography” , whilst striking and innovative, it’s not my personal preference. Still given all images have been “photoshopped” to some degree, if you like it, go for it.
I think this is neither art nor photography but instead data visualisation, and in fact a valid thing to do. There are lots of examples in science and medical imaging where a grey scale image with a high dynamic range is visualised with pseudo colour mapping.
As a quick and dirty example on a stretched mono image (eg Ha) you could try
R: abs(1.0 - $T)
G: abs(0.5 - $T)
B: abs(0 - $T)
[EDIT] Attached is a Lagoon Neb Ha image. The colours really aren't the best for showing the detail, but as I said, it was quick and dirty!
With trial and error you could adjust the constant values in each expression down until it could be applied to an unstretched image. There are lots of other (better) pseudo colour palettes that could be used but they would use more complex RGB expressions.
Last edited by kosborn; 15-03-2021 at 10:57 AM.
Reason: added image
Really nice details and good image scale. Your star field looks good too. The bicolor version with enhanced highlights is posterized though so there must be some clipping in one of the channels and data loss. Other than that It's very good Ha data.
I can see the application from a technical/scientific viewpoint as it would help to visually enhance areas of high dynamic range. If used to highlight colours from an aesthetic perspective it would then probably move in to the realm of Astro Art as opposed to astrophotography. That’s is fine as well of course, it just depends on where we land on this and what our objectives are when processing our image data.
thoughts ......
Depends whether you want to do art or photography, there’s been a few images that I felt fall into the Astro art with a camera category, rather than “astrophotography” , whilst striking and innovative, it’s not my personal preference. Still given all images have been “photoshopped” to some degree, if you like it, go for it.
Thanks for input Clive.
The difference between Astro Art vs Astro Photography is still quite a blurred line for me.
Maybe one day I will work it out.
Quote:
Originally Posted by kosborn
I think this is neither art nor photography but instead data visualisation, and in fact a valid thing to do. There are lots of examples in science and medical imaging where a grey scale image with a high dynamic range is visualised with pseudo colour mapping.
As a quick and dirty example on a stretched mono image (eg Ha) you could try
R: abs(1.0 - $T)
G: abs(0.5 - $T)
B: abs(0 - $T)
[EDIT] Attached is a Lagoon Neb Ha image. The colours really aren't the best for showing the detail, but as I said, it was quick and dirty!
With trial and error you could adjust the constant values in each expression down until it could be applied to an unstretched image. There are lots of other (better) pseudo colour palettes that could be used but they would use more complex RGB expressions.
Thanks Kevin.
A very interesting contribution.
I love the term 'data visualisation'.
Yes I will continue to play with pixelmath
Quote:
Originally Posted by multiweb
Really nice details and good image scale. Your star field looks good too. The bicolor version with enhanced highlights is posterized though so there must be some clipping in one of the channels and data loss. Other than that It's very good Ha data.
Thanx Marc, who knows what I did to the data!
Quote:
Originally Posted by Ryderscope
I can see the application from a technical/scientific viewpoint as it would help to visually enhance areas of high dynamic range. If used to highlight colours from an aesthetic perspective it would then probably move in to the realm of Astro Art as opposed to astrophotography. That’s is fine as well of course, it just depends on where we land on this and what our objectives are when processing our image data.
Well said Rodney, and who knows where we will end up...
I think this is neither art nor photography but instead data visualisation, and in fact a valid thing to do. There are lots of examples in science and medical imaging where a grey scale image with a high dynamic range is visualised with pseudo colour mapping.
As a quick and dirty example on a stretched mono image (eg Ha) you could try
R: abs(1.0 - $T)
G: abs(0.5 - $T)
B: abs(0 - $T)
[EDIT] Attached is a Lagoon Neb Ha image. The colours really aren't the best for showing the detail, but as I said, it was quick and dirty!
With trial and error you could adjust the constant values in each expression down until it could be applied to an unstretched image. There are lots of other (better) pseudo colour palettes that could be used but they would use more complex RGB expressions.
I agree with that approach. It is data visualization and as long as the ratios mapping to RGB are presented and no individual channel color manipulation, sharpening, levels or worse masking was done after the blend then it is a valid image. I did blend in the past Infrared and Sii as a bicolor image.
I just never thought about assigning the same data to different channels with different weights. That is more like modifying the dynamic range in each channel. I assume if the weights were 1:1:1 you'd end up with a monochrome image.
I agree with that approach. It is data visualization and as long as the ratios mapping to RGB are presented and no individual channel color manipulation, sharpening, levels or worse masking was done after the blend then it is a valid image. I did blend in the past Infrared and Sii as a bicolor image.
I just never thought about assigning the same data to different channels with different weights. That is more like modifying the dynamic range in each channel. I assume if the weights were 1:1:1 you'd end up with a monochrome image.
The example I gave was very contrived because all I was doing was mapping the shades of 8 bits per pixel of grey already visible into an arbitrary colour map. The benefit is really when visualising an image with more than 8 bits of monochrome data per pixel. Our computer displays can only show 8 bits of grey scale but when mapping different parts of the grey scale to different contrasting colours the visible dynamic range of a 14 bit or 16 bit image is increased. Instead of assigning weights to the channels, it's a matter of mapping different sections of the grey scale to different (contrasting) colours. It's not pretty (in fact the Lagoon Neb example I posted was ugly AF!) but it's not about aesthetics, instead it's about visualising the data.
I think its super cool, and data visualization is A O K in my book. Narrowband, for me, is also data visualisation.
Is this process similar to what Peter did with his statue of liberty for the big astro competition last year? It was fully Ha mapped to colour based on intensity?
well I don't know if it's art or science Peter, but I sure like the second one.:-) I'd love to see the colours from the first brought in to the second while retaining the smoother toning and absence of posterization you have in the second.
