|
|
|
|
Selective Luminance Layering
Some images can be clicked on for larger view
Since I now image with a high quality TMB 130 mm F6 and Tak mount, I am starting to get very nice wide field images. However, at almost 2 arcseconds per pixel, I am missing the higher resolution I used to get with my RCX 12 inch. For that reason, I have developed this system of selective luminance layering so that I could combine the small FOV high res images from the RCX with the wide field of the TMB APO. That way I get the nice wide FOVs and keep a lot of the internal resolution and detail in the object I am imaging.
Here then is the wide field M81, right out of the ST4000XCM with basic processing. It is a pretty good image in it's own right, with excellent color and background, but lacking detail. The second image is a cropped version, and for the rest of this page, cropped images will mostly be used.
|
|
|
I have however, another image on the site of M81 taken with the RCX 12 inch @ F7, ST2000 cameras ( mono and color), and AO7. As you can see, it has nice detail, but a small FOV and grainy background
|
|
Combining them however is not that easy at first glance...Rob Gendler's Multiple Luminance Layering is the thing to do, but how...Just registering and combining produces unaccptable borders in the image..I tried selective cutting but still had ugly boundries. It wasn't till I went to AIC and heard Ken Crawford's presentation " Depth of field Processing" with it's selective processing and layer masks, did this all come together.
The first step is to extract the luminance data from the LRGB high res RCX M81 image, rotate it best it can be to match up with the previous XCM image, and then register is against that image in Registar. Here are the results of those steps:
|
|
|
|
Next, take the registered luminance, and the original XCM image into PS, layer the lum onto the XCM, apply a layer mask hide all, and carefully, remembering where the borders of the luminance image are, strip away the mask at just the galaxy itself with the erasor tool, at whatever rate you are comfortable ( I like 50% opacity/50% flow)......then, before flattening, apply a Guassian blur of about 10 pixels, flatten image, and voila......
|
|
|
Here then is a side by side comparison of the plain XCM image, and the selective luminance layered image, after final touch-ups in PS :
|
|
|
