Mike's New Astroart Colour Plugin

v1.21

This is an alternative colour synthesis plugin for the Starlight Xpress MX5C, MX7C and the future SXV-H9C single-shot colour astro-cameras.

Having found the Star2000 software hard to use to extract colour and the Astroart plugin generates images which are too fuzzy and too pink, I decided to write my own. This is the result.

Donations

If you want to make a voluntary donation for use of the plugin, click the following button:-

15-Apr-2005: It has been reported that payment attempts with the button above fail.  I have discovered that donation using the Firefox browser works, while payment with Internet Explorer fails with an error message about 'session timeout'.  So it looks like either recent security fixes have broken IE or the Paypal pages are incorrectly scripted.  Both of these are beyond my control!

Alternatively, send me a gift certificate from Amazon.co.uk.

User Group

A user group exists on Yahoo to support this plugin as well as being a general place for discussion about colour CCD processing in astrophotography and other areas.  You can get to the group at http://groups.yahoo.com/group/colour_ccd.  I vet all membership to prevent spam since this has worked well on another group I run.  However, anyone with an interest in the plugin or the general area will be allowed membership.  Just write a few words to allow me to tell if you are a spambot or not!

Features

The features of this plugin are:-

• Simple to use
• Fine tuning of colour balance using RGB levels
• Automatic white balancing based on the whole image or just part of it
• 3-step luminance sharpening
• Ability to compensate for atmospheric colouring
• Supports images taken with Star2000 and Astroart
• Resizeable preview window
• Optionally outputs red, green, blue and luminance planes to separate windows to allow processing with Astroart trichromy tool
• Optionally writes colour image to a bmp or .jpg format file
• Works with AstroArt Light, AstroArt 2.0 and AstroArt 3.0
• Instant colour images from daylight photos - no more green pictures!
• Linear and gammalog stretch functions for the luminance component
• Extracts colour from images that the normal Astroart plugin struggles with
• Batch processing of multiple FITS files
• Handles flat frames and dark frame processing if required
• LRGB combination of external FITS files
• Support for Starlight SXV-H9C, SXV-M8C and SXV-M25C cameras
• Automatic filter grid detection - no more guesswork!

Credits

Thanks to Janet Cutler for trialling the plugin in its early days and giving me some useful feedback.

Download

v1.21 (download)

• improved colour extraction for Bayer camers (SXV-M25C, SXV-H9C, SXV-M8C)
• improved colour extraction for CYMG cameras (MX5C and MX7C)
• added an interlace adjustment control to lighten or darken even scan lines for MX5C and MX7C images
• remove the VBE filter since this is now replaced by the interlace adjustment

History

v1.20

• fixed a problem with subframes and images with an odd number of columns
• fixed a couple of problems with camera identification

v1.19

• Added support for SXV-M8C and SXV-M25C
• Added automatic filter grid alignment algorithm.  This can't yet cope with flipped MX5C and MX7C images.

v1.18b

• Fixed a problem with HSL2RGB and RGB2HSL.  I discovered that the routines I have been using so far should have contained code to blend colours to white at high brightness levels but this was missing in the code I originally used.  I found some better routines on the web which give much better results.
• Fixed a problem where saving to a .jpg file gave an overcompressed image.
• Fixed a maths error when loading an image taken with MaximDL

v1.17

• improved colour extraction from CYMG images i.e. those taken with Astroart.
• improved LRGB routines - gives much better saturation of images.
• fixes to prevent coloured stars

Here are two images that show the improved colour accuracy between v1.16 and v1.17.  The image details are:-

Camera: MX5C attached to a True Technology MFU + Baaded IR/UV filter + 150mm camera lens
Software: AstroArt 3 plus plugin
Target: GretagMacbeth ColourChecker card

This one is proecessed with v1.16:-

This one was processed with v1.17:-

v1.16

• added a dropdown box to set the Y pixel offset.  This allows for 0-3 pixels offset - needed for some images.
• fixes support for MaximDL-captured images.  These need a Y offset of 2 pixels so this is set automatically when a new image is loaded.  They also are in YUV format, not CYMG as I had originally thought.

v1.15

• Added support for FITs files take with MaximDL
• Reduced memory usage by using 32-bit floating point instead of 64-bit floating point

v1.14

• Added code to make sure generated FITS files are always 16-bit
• Corrected a problem where some parts of an Astroart image could be clipped to white prematurely.

v1.13

• Some minor improvements and bug fixes

v1.12a

• Added LRGB recombination controls
• Added support for Starlight SXV-H9C single-shot colour images
• Improved luminance frame generation to remove colour filter 'grain'.  Allows higher levels of high-pass filtering.

v1.10

• Updated to support AstroArt 3.0.
• Batch processing a bit quicker because the preview window is no longer being updated after every image.

v1.09

• When doing batch colour separation, this new plugin no longer performs histogram stretching or high-pass filtering of the luminance frame. This allows the luminance frames to be summed or averaged in an external program. Previously, the luminance frames of faint objects generated by the batch LRGB splitter feature could not be stacked properly because the pixels brightnesses in the luminance frames had already been stretched to fill the range 0-65535. The colour images are generated as before and can also be summed or averaged.
• The plugin can detect a MaximDL interlaced image but currently can't extract an image from it. This will be in the next update, hopefully.

v1.08

• Fixed a floating point bug with certain types of image file
• Changed flat field processing

v1.07

• Fixed handling of 12-bit images from MX5C cameras
• White balancing now works properly

v1.06

• Added batch processing
• Added spin buttons to numeric entry boxes

Instructions

Basic instruction on how to use the plugin are here. Email me if you have any problems (remove the N_OS_PA_M bit before sending your email).

Note that this plugin has not been tested on an MX5C images. If you have a problem with MX5C images with the plugin, send me an email and attach a zipped up image - this will help me a lot.

Test Images

Here are some sample MX7C images to play with:-

• M57 (585kbytes)
• Car & Boxes (804kbytes)
• Bookcase (780kbytes)

The Car & Boxes picture was taken with my own camera driver and so doesn't have the correct FITS header. Click off the 'Auto Format Detect' tickbox on the first tab in the setup dialog and select 'Starlight Interlaced' to get the correct colours with this photo.

Here the images above processed with the plugin (with default settings):-

This is an unguided image of M42 taken using Astroart with a Starlight Xpress MX7C camera as 16x30s exposures using Hires Progressive mode. The 16 raw images were batch processed by this plugin and then LRGB frames were then averaged together and then recombined with the Trichromy tool.