Question: A New Approach to the Combination of Broadband and Narrowband Data

[David Raphael]

I am working on a new script to implement Vincent Peris's N-Band and B-Band combo tutorial ...

Of course I haven't really successfully used his technique either ;-)  That is why I decided to write a script with it.  So I can play with all the variables and automate the workflow...

Here is the link to the script.  It is a major work in progress...feel free to try it out, but I can't promise that you will get a satisfactory result at this point.

http://pixinsight.com/forum/index.php?topic=2127.0

However, I am stuck on the last part of his tutorial:

Quote from the tutorial:
"Once we have the best fit between both luminances, we'll transfer the CIE a* and CIE b* components from the HaRGB composite to the HaGB composite. The resulting color-corrected image can be seen on Figure 19. "

How the heck does one transfer the CIE a* and CIE b* components from one image to another?  Is it a MTF of some sort?


Any help is greatly appreciated.

Cheers,
Dave

[Niall Saunders]

Hi Dave,

Let's see if I can explain this without using pictures

You have a tri-colour HaGB image that you run through <(L.a*.b*)ChannelExtraction> to give you three new mono images, <L_HaGB>, <a*_HaGB> and <b*_HaGB>

You also have another (mono) image that was the result of another similar <Lab Channel Extraction> - only this time you have 'thrown away' the <a*> and <b*> images (as you won't be using them) and have just kept the <L_HaRGB> image - as this is the image that you WANT to be using.

Now, you can also 'throw away' the <L_HaGB> image from the first channel extraction - in fact you never really needed to 'extract' it in the first place (same goes for the <a*_HaRGB> and <b*_HaRGB> images from the second extraction - just dont 'tick' the appropriate <R>, <G> or <B> boxes)

Finally, you can now use the <(L.a*.b*)ChannelCombination> process to make a 'new' RGB composite image, but this time using the <L_HaRGB> image (from the second extraction) and the two <a*_HaGB> and <b*_HaGB> images (from the first extraction).

Because you took the time to 'balance' the luminance of the HaGB image to the luminance of the HaRGB image, the end result should be 'as bright' as the either of the originals - just with the 'detail' being emphasised by the detail contained in the second image.

It is probably eaisest to just perform the two channel extractions first - leaving you six images. Then perform two recombinations - building two COMPLETELY NEW colour images - only you 'swap' the two <L> channels in the recombination process.

Then just copy all four RGB images to a new Workspace (these will be the two 'original' and the two 'new' images) and then use the <Windows><Tile Windows> menu option to lay the images over the workspace for you to compare 'side-by-side'.

Clear as mud

Cheers,