API reference

The public API is re-exported from the top-level delta package. There are two layers.

High-level pipeline

The headline path most users want — coerce inputs, fit a spatially-varying kernel, subtract, and (optionally) decorrelate and score:

delta.subtract(...)  ──▶  DiffResult  ──▶  KernelSolution
        │                     │
   Subtractor            .write("diff.fits")
   (reusable config)     .difference / .variance / .mask / .score

• Pipeline — subtract (one-shot wrapper), Subtractor (reusable configuration), and DiffResult (the products of a run).
• Kernel solution — KernelSolution, the serializable fit result (basis params, knots, coefficients, diagnostics) with .save / .load and FITS provenance.
• Inputs — as_layers and synth_variance for input coercion and noise synthesis.
• Validation — synthetic source injection/recovery helpers.

Low-level core

The C++ core (delta._core) is also re-exported for advanced use — basis evaluation, convolution, the GLS solver, thin-plate splines, detection, decorrelation, and FITS I/O. These are the building blocks the high-level pipeline orchestrates; most users will not need them directly. See Core (low-level).