ArcsinhStretch - ensure same black point and stretches across 28-panel mosaic

[Rudy Pohl]

I am working with a 28-panel mosaic of a full arch Milky Way landscape composition.

Each panel consists of 10 images shot at 6 seconds each, stacked and calibrated with darks, bias and flats in Pixinsight. Each stack will have Automatic Background Extraction applied at identical settings and each stack will have Background Neutralization and Color Calibration applied.

To stretch and enhance the colours I am trying to decide whether to go with Mark Shalley's ArcsinhStretch which yields more robust colours on these stacks, or to go with a Histogram Transformation Stretch followed by a Luminance extraction and an LRGB recombine. The benefit of the second method is that it can apply all the same values to each of the 28 stacks and so yield a consistent result needed for seamless stitching of the full image.

My difficulty with ArchsinhStretch is that I do not know how to ensure that I can get the identical black point and identical stretch factor applied to each of the 28 stacks. Also, the bottom row of 7 panels (stacks) includes a thin horizon and trees. When I apply the "Estimate Black Point" button to a stack with the horizon and trees included I get one pair of settings for Black Point and Stretch Factor, but when I take the same stack and crop off the horizon and trees I get a very different black point and stretch factor.

So my question again is, how can I ensure that I can apply the same black point and stretch amount to all 28 stacks that comprise this mosaic so that when stitched together they will blend seamlessly?

Thanks very much,
Rudy

[pfile]

you should probably be assembling the mosaic from linear files and then processing the entire image in one go. its going to be really, really hard the way you are proposing.

rob

[sharkmelley]

you should probably be assembling the mosaic from linear files and then processing the entire image in one go. its going to be really, really hard the way you are proposing.

rob

Agreed, keep everything linear until the whole mosaic is assembled.  It will then be far easier to match the panes together.

Mark

[Rudy Pohl]

HI Mark,

I use Microsoft ICE for stitching because it does such a fabulous job and is so easy tot us. Are you suggesting I stitch the panels together in Pixinisght?

Rudy

[sharkmelley]

Yes you can stitch linear panels together in PixInsight.

If you want to use ABE, BN and ArcsinhStretch and then export to Microsoft ICE then you might find the same ABE, BN and ArcsinhStretch settings work for all the panes.  I don't know.

Mark