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NGC Objects Thumbnails for object planner?

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You could just script the color correction in PixInsight, which will likely result in a better image. I assume these are FITS?
6 years 11 months ago #16095

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I decided to only pull the DSS2r (red channel) images for these. It appears the original DSS images are at a lower resolution and they don't have a DSS2g channel run. I made the assumption that the DSS run was the green channel. Anyway, I figure black and white thumbnails of the red channel would be adequate. I have pulled all 7840 objects and the files are in jpg format in 500x500 pixel files. I need to convert them to PNG files next. The initial challenge is that the png files are significantly larger than the jpg files on conversion. I need to figure out what compression syntax to use in mogrify to get the size back down to jpg levels which makes the images about 25k each. The current png conversions are coming out over 120k each.
6 years 11 months ago #16102

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I just noticed the thumbnails in kstars that are already there are only 200x200. Let me resize or repull the images at that size. That should reduce their disk space nicely.
6 years 11 months ago #16104

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I have a request to help me get the sizing of the objects correct in the frame. I believe you have the apparent size listed in all of the NGC objects. Is there any way you can send me a comma separated output with the NGC number and the apparent size in arcmin for each object? What I can do from there is use that data as input for the script to pull down the image with the proper sizing straight away instead of just picking a set size and correcting from there.
6 years 11 months ago #16105

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I found an excel spreadsheet table of NGC objects that should work. This will allow me to pull the appropriate field of view for each image.
6 years 11 months ago #16106

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I have come up with a formula I am happy with. Using the NGC spreadsheet and the apparent diameter values in that, I have been able to a customized query for each NGC object in the database. I am pulling the Red images from the DSS2r survey. I adjusted the size of the thumbnail based on the size of the object. I made the minimum size of the thumbnail 200x200 pixels the maximum size to be 1000x1000 pixels and the image content will be scaled to the size of the target object unless the object is smaller than 2 arcmin in which case the thumbnail will cover 2 arcmin for those objects. Basically, it scales linearly up until 10 arc min for 1000x1000 and after that, everything larger than that will be scaled down to fit into 1000x1000. It was a tradeoff between detail and file size. I think this will work out.
I am doing a pull of the 7840 objects now. If I like how they come out, I will try one additonal pull with RGB settings which will take 3 times as long to see if they come out any better than the first few attempts. After that, I will convert them to PNG format and crush them using pngcrush. At that point, I should be able to tar them up and send them to you for review. Please let me know if there is any additional information you would need from me.
Last edit: 6 years 11 months ago by John S..
6 years 11 months ago #16107

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I have completed all of the NGC object pulls and reduced their size with pngcrush. Theoretically, you should be able to unzip the archive to the $HOME/.local/share/kstars directory and have all of the NGC thumbnails available to you in the Observation planner. I put all of the duplicate objects into a folder in the archive call ngcdupes. I did not want to replace the 47 color NGC object thumbnails that were already included in the program, but wanted to have them in case they were needed. The zipped tarball of the images is 281MB in size. How would you like me to get it to you?
6 years 11 months ago #16131

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I have installed this on two of my machines and both seem to be working fine. If you can get me a CSV listing of all of the IC objects and their sizes in arcmin, I can do the same process for the IC catalog.
6 years 11 months ago #16132

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Sure, here is what I was able to make so far: www.dropbox.com/s/uachga3n5ii7ra0/ngcic.cvs?dl=0
6 years 11 months ago #16134

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Are the major and minor axis the apparent size in arcmin for x and y?
6 years 11 months ago #16136

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I have built scripts based on the major and minor axis values being the X and Y sizes in arcminutes. I have done a test pull of IC 10 and can confirm that the thumbnail works when copied to the $HOME/.local/share/kstars directory. I am going to go ahead and do the same run to grab and compress all of the PNG files for the IC list. I should be able to complete that tomorrow and upload both the NGC list and the IC list thumbnails to wherever you need me to send them.
6 years 11 months ago #16139

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This sounds very good. I have been working on improving the "what's interesting" view in kstars and could really use some images for Ngc objects. Larger than 200 and smaller than 1000 pixels per side would be good for that view. Somewhere in the middle (500ish?) would be very good. A download of all would be good but being able to programmatically download them would be good too.
6 years 11 months ago #16141

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