Parallel Vision
Cross Vision
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After a long, frustrating period, we finally had kind of clear skys!
There is many "Schools" in astro imaging, some are more purist, than others.
I have some principles in my work too.
As an astro imager I don't add anything to images.
Only manipulation done is Stretching, curves and levels.
As an artist I balance different components in an image differently,
so I can show the hidden beauty by a way I like to.
MAXIMIZE YOUR BROWSER AND
CLICK THE IMAGE TO START THE SLIDESHOW.
An older image of Heart&Soul, details can be found HERE.
In the next image objects can be clearly seen after a Star removal procedure.
If Stars are removed with care, no information from actual target is lost.
If there is some minor details lost during a procedure, they are placed back automaticly, when Stars are placed back to a image.
When Stars are removed, it's easy to use Levels and Curves to boost actual data. There is now no need to worry about bloating Stars.
Since Stars has no relevant color information in a Narrowband image, this method can be used. In a Broad band RGB-image stars has real colors.
The same method can be used for RGB-image as well, if Star information is handeld correctly and replaced back to an image after manipulation.
In this image Stars are placed back. Whan stars are in separate layer over the Starless image, the tranparency can be tweaked carefully to balance visibility of Stars and Objects.
There is several methods to combine Stars and Objects. Stars can be placed as a Lighten mode in PS or by using the Screen mode. The right method depends of imagetype and some testing is needed by a user. Images can be combined by simply stacking them to gether as well.
We can't use H-a as a luminance alone, since it doesn't containe any information from other channels.
the weak signal from S-II and O-III channels is added to a H-a luminance
by a method descripted in a Tone Mapping PDF-document.
The result can be seen in the image abowe.
This image has all the color information from the Starless channels combined to a HST-palette.
I call it to a Color Map.
In this color palette, the idea is balance colors so, that no line is dominatring the color scheme.
Usually the H-a is the strongest channel and HST images tend to have a strong Green cast doe that.
With this method, cahannels are easy to stretch equal, sice there is no stars to worry about.
Very weak signal can be used, but it's allways better to have enough signal to work with.
The final image combined from a Tone Map and Color Map images.
As can be seen in a image, there is no Purple halos around stars, as typically seen in a HST-palette images, doe the strong stretching usually needed for a weaker channels.
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A Tonemapping Procedure diagram.
Download the PDF-document of Tonemapping from HERE.
An Animation of Tonemapping procedure.
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Please, if you have tested this method, send a comment here.
Direct link to a you Tone Mapped image could be nice as well.
I need some feedback to be able to further improve this Work flow.
Original RGB-image from 2007
RGB + Natural color narrowband data 50%/50%
RGB + HST-narrowband.
Mixed 40% as luminance/60%HST + star color 100% from RGB
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For Parallel Vision
For Cross Vision
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Cross Vision
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Parallel