Spectral Astro Stacker ---------------------- David Beynon (dave@spectral3d.co.uk) Introduction ------------ sas are a set of simple utilities intended for merging large stacks of photographs without consuming too much memory. It was originally designed for the creation of "Star Trail" images, although it has grown to encompass averaging and denoising operations. Currently the following tools are built. sas_merge - merge images sas_dump_pref - dump or generate preferences sas_list - list "stars" in an image Building -------- The current version is 0.5.1 You need to have the "FreeImage" library and headers installed. The version I have been using is 3.15.3. Code is written in C++, and has compiled under current versions of g++ and clang++ so hopefully building should be a matter of typing "make". sas_merge --------- sas_merge is the main image merging tool. If you type "sas_merge" or "sas_merge -h" you should see the following help text: Spectral Astro Stacker 0.5.0. Copyright (C) David Beynon 2014 Usage: sas_merge [options] ... Options: -h : This help text. -p : Load preferences file. -d : add dark frame. You may have many of these. -o : Set output file. Default is "merged.png". -t : Set merge type. Default is "n". Merge types: n : denoise/averaging. a : denoise/averaging with alignment. t : Lighten/star trails. Currently there are no other options. Dark frames, output files and merge controls should come before the input files on the command line. Currently only 16 bit/channel tiff, ppm and png are supported for output. Anything FreeImage can cope with is fine for input. sas_dump_pref ------------- sas_dump_pref is a simple tool for writing preferences to stdout. If its output is redirected to a file then it can be used as a preferences file. If it given no command line arguments then it will output defaults. If it is passed a prefs file then it will read it, then output a new set of preferences reflecting the input. This can be used to update your preferences when new ones are added. sas_list -------- sas_list will search for stars in an image, and write results to the terminal, brightest first. This can be helpful when debugging preferences. Star List 0.5.0. Copyright (C) David Beynon 2014 Usage: sas_list [options] Options: -h : This help text. -p : Load preferences file. Output format: X, Y, Brightness, Size (pixels) Output is sorted brightest first. Preferences ----------- The current preferences are currently used. find_stars_trigger_threshold - how much brighter than the background does a pixel have to be to start identifying a region as a star. Must be betwen 0 and 255. find_stars_exit_threshold - intensity above background at which we stop treating an object as a star. Must be less than find_stars_trigger_threshold find_stars_min_pixels - The minimum size of an object to be treated as a star. find_stars_max_pixels - The maximum size of an object to be treated as a star. find_stars_max_stars - The maximum number of stars used for alignment find_stars_blur_radius - Filter size used to create background. align_stars_consensus_error - How close star positions have to be before we accept that they are successfully aligned. remap_image_aa_type - Type of antialiasing used for image remap. Currently supported values: 0 - no aa. Fast but low quality. 1 - "Lanczos 2" aa - high quality but v slow. Others will be added in due course. Please report any problems, or suggestions to dave@spectral3d.co.uk.