DeepSkyStacker is a freeware for astrophotographers that simplifies all the pre-processing steps of deep sky pictures.

　　Registering

　　Stacking

　　Simple post-stacking processes to quickly view the final result.

　　Saving the resulting image to a TIFF or FITS file (16 or 32 bit)

　　After a shooting night you give all your pictures (light frames, darks frames, offset/bias frames, flat frames) to DeepSkyStacker and you go to bed. The next morning (or is it afternoon?) you can see the result and start post-processing.

　　DeepSkyStacker: Main Features

　　Automatic registration of a set of pictures

　　Automatic detection of stars using all the picture area

　　Preview of registered stars

　　Sub pixel registration

　　Automatic derotation

　　Automatic creation and use of offsets, flats and darks frames

　　Sub pixel alignment and stacking

　　Supported bitmaps formats : 8, 16 and 32 bit colour and monochrome TIFF files, 8, 16, 32 and 64 bit colour and monochrome FITS files, JPEG, BMP, PNG

　　Native use of RAW files from most DSLRs (CR2, NEF, CRW, DNG ...) without using an intermediate file format (TIFF or other).

　　Darks, Flats and Offsets computed from and applied directly to the RAW picture before any interpolation.

　　Stacking methods: average, median, kappa-sigma clipping, auto adaptive weighted average, entropy weighted average, maximum...

　　Preview of all pictures (including RAW)

　　Simple post-processing with RGB levels, luminance curve and saturation adjustments.

　　Save the resulting picture to 16 or 32 bit TIFF or FITS files with or without adjustments applied.

　　Simple and intuitive user interface

　　Optimal memory usage: the same amount of memory is required to register and stack 10 or 500 pictures.

　　Optimal usage of all available processors (hyperthreaded, multiprocessors, duo and quad core processors)

　　English, Spanish, French, Czech and Italian versions

　　DeepSkyStacker: Advanced Features

　　Automatic determination of Darks, Flats and Offsets to be applied to the pictures using ISO speed and exposure time.

　　Several methods to optimize the RAW files processing by using the best of the Bayer matrix without interpolating the missing pixels.

　　Option to automatically detect hot pixels and during the registering process

　　Options to automatically detect and remove hot pixels and bad columns during the stacking process

　　Options to detect and clean hot and cold pixels remaining after calibration.

　　Automatic flat calibration to equalize luminosity differences

　　Automatic calibration of pictures background for each channel

　　Automatic Dark Optimization

　　Automatic use of a bicubic, bilinear or bisquared alignment transformation depending of the number of stars.

　　Creation of File Lists to speed up loading of often used files (darks, flats, offsets/bias...).

　　Comet Stacking

　　Manual edition of stars and comet positions

　　Drizzle option (x2 or x3) during the stacking process.

　　Possible use of B&W 16 bit FITS files like RAW files (automatic use of a Bayer Filter Pattern).

　　Use of File Groups to simplify multiple nights on the same object file management.

　　Options to create a calibrated and registered file for each light frame.

　　Cosmetic options to detect and clean remaining hot/cold pixels from calibrated images.

　　Feature to create Star Masks

　　Feature to batch multiple stacks

　　Command-Line version

　　What is not DeepSkyStacker?

　　DeepSkyStacker is not a post processing software with advanced options like noise reduction, wavelets, unsharp mask...

　　DeepSkyStacker cannot be used for planetary pictures registering and stacking.

　　There is a lot of software (some free, some not) for these tasks: Pleiades' PixInsight, Iris and of course Photoshop to name a few.