親子觀星會

FROM FB

COLOUR MOON TUTORIAL/GUIDE!
A few people have asked how I get the colour in my Moon images so I have written out this very basic guide that might help.
Its not my full process, but should be enough to get you started and experimenting.


RECORDING AND STACKING

    Record a video of the Moon in RAW. 1 to 4 min should be more than enough.

    Copy the .avi from the SeeStar to your computer.

    - Load the .avi into Auttostakkert!4 (https://www.autostakkert.com/)
    Image Stabilization = Planet (COG)
    Quality Estimator = Automatic
    Colour Menu > Force Bayer GRBG

    Press the "Analyse" button.
    AS!4 will review every video frame, rank them from best to worst quality, and display the results on a graph.

    In the window that has the image of the Moon in it, choose an AP size (I usually pick 104), select "Replace" and "Multi-Scale," then click the "Place AP Grid" button. This will put a whole bunch of boxes on the Moon.
    Check to ensure they cover the whole of the Moon but aren't selecting any of the black area around the outside of the Moon.
    If some black is selected, increase the "Min Bright" option until just the Moon has APs on it.
    If not enough of the Moon is covered (especially around the terminator), decrease the "Min Bright" option.

    Look at the graph and decide how many frames you want to stack. You only want to use the highest quality frames, so sometimes "less is more."
    I usually only stack the best 50%. To do this, I look for where the green line meets the 50% axis on the graph, hold down "ctrl," and left-click on the graph. This will automatically fill the first box in the "Frame percentage to stack" box.

    Choose your file format.

    Tick "RGB Align" and "Save in Folders." The "Sharpened" option will output a 2nd image with sharpening applied.

    Drizzle 3.0x works well for the SeeStar. The Optics/Sensor combo is slightly undersampled, so Drizzle can help to recover that detail. The more frames, the better it will work (but don't include low quality frames just to get the numbers up), and you can always downsample the image after to return it to the original size. It might not always work correctly, so if you find a lot of aliasing or blocky artifacts, drop it down to 1.5x or turn it off completely.

    Press the "Stack" button and let AS!4 do its thing. Once done, there will be a new folder in the same dir as the .avi that contains the stacked image.

PROCESSING
I use "AstroSurface" (http://astrosurface.com/) for this part.

    Load the image into AstroSurface. "Files > Open File" or "Ctrl-O." Browse to where AS!4 saved the stacked image, select it, and choose open.

    The first thing I usually do is "Crop" the image. At the top of the AstroSurface window is a button labeled "Crop." Select it, then draw a box around what you want to keep. Crop out any 100% black around the border that may have been added during stacking.

    The next step is to sharpen the image. These are the "Orange" buttons at the top.
    There are 5 options to choose from. What option you choose will be down to personal preference as they all have slightly different results, so play around and find the one you like the look of the best.
    I like to use V-Cittert or R-Lucy.

    I won't go into details on how to use these tools, but the AstroSurface has some videos. Wavelets Wiener - http://astrosurface.com/manuels/waveletswiener.mp4 and V-Cittert - http://astrosurface.com/manuels/vancittert.mp4. The others all work similarly, so have a play.

    Once you are happy with the sharpening, the next step is to get that colour. I start by doing a "White Balance." It's one of the blue buttons and is labeled "W-Balance." Click the "Auto" button and press OK (This is why we cropped out the 100% black earlier).

    Next, click the "Saturation" button (also blue). Draw a small box over the Moon. Crank the "Color Noise prefilter" up to 5 and set a saturation value. I do this in a few small steps rather than a single one, usually around 50. It will be subtle, but the colour is there. Press the "Do All" button and then "OK".

    Your image may have a blue tint to it again, so do another Auto White Balance.

    Repeat the saturation. 50 again should be ok. This time, you don't need to use the "Color Noise prefilter."

    Do another white balance if you feel it's needed.

    Once you're happy with the results, choose "File > Save As". If you click "Save," it will OVERWRITE your stacked image. Not ideal if you want to start the processing again, as you will need to start again from AS!4.

    Bring into Photoshop, GIMP, or your editor of choice to make the final adjustments.

Hope this helps some people. Feel free to ask questions in the comments. I'll do my best to answer.

https://www.facebook.com/photo/?fbid=10168324756015164&set=gm.321854700626819&idorvanity=201735739305383