Imaging

Synthesizer can be used to generate photometric images or property maps.

The main public interface to this functionality is the high-level galaxy and component imaging API used together with a PhotometricImager. In this workflow you:

  • generate spectra and photometry

  • construct a PhotometricImager

  • call galaxy.get_images_luminosity(...) or galaxy.get_images_flux(...)

  • optionally apply instrument-owned PSF and noise configuration through that same workflow

(Or simply call the appropriate property map method on a component or galaxy, which will use the same underlying workflow without the emission specific steps.)

These methods will return either an Image or an ImageCollection depending on the number of bands requested. The Image and ImageCollection classes are the main data containers for imaging data in Synthesizer, and they provide a consistent interface for working with images regardless of how they were generated.

  • Image for individual images

  • ImageCollection for related multi-band images

Histogram and Smoothed Imaging

For particle distributions, Synthesizer implements both histogram based imaging, where pixel values are sorted into individual pixels, and smoothed imaging, where pixel values are smoothed over kernels to produce a continuous image. In contrast, for parametric components and galaxies there is only smoothed imaging, where the pixel values are calculated from the parametric model and smoothed over a Morphology object.

Histogram images are simple and fast, only requiring positions and pixel values as inputs. However, in the vast majority of cases this method is not suitable for realistic, scientifically accurate imaging. When working with particles that are representative of a smooth distribution the smoothing of the particles must be taken into account.

In Synthesizer, this is done by combining a Kernel with the smoothing lengths of the particles. This means smoothing_lengths must be provided for each particle in the input data.

Generating Images

The pages linked below provide detailed walkthroughs of how to generate images and property maps using Synthesizer, including examples of how to use the various imaging methods and classes.