Arguments Explained

A reference to the key bmquilting synthesis parameters and how they affect output quality.

1. Common Arguments

These core concepts apply to both square and circular patching implementations, though units and behaviour differ.

Block Size / Diameter

The fundamental unit of synthesis. It defines the size of the patches extracted from the source textures.

  • In Square Patching: Defined as block_size in pixels.

  • In Circular Patching: Defined by the diameter, which must be an odd integer.

  • Latent Space Note: For processing latent images, dimensions should be adjusted according to the latent space; e.g. dividing by 8 for Stable Diffusion.

Impact:

  • Larger blocks: Faster generation (fewer patches needed) and better preservation of large-scale structures. However, they require larger source textures to provide sufficient “addressable area” for variety.

  • Smaller blocks: Better for fine-grained textures but may struggle with large patterns, leading to “broken” continuity or repetitive artefacts.

Overlap

The region where adjacent patches are blended together.

  • Square Patching: Defined as overlap in pixels.

  • Circular Patching: Defined by the overlap_ratio (a percentage of the radius, from 0.0 to 1.0). The resulting overlap_radius determines the width of the blending ring.

Impact: A larger overlap provides more data for the matching algorithm to find a seamless fit and more space for blending. However, it effectively reduces the “new” area each patch adds, requiring more patches to cover the same output size.

Tolerance

The strictness of patch matching.

  • Patch candidates are those with error <= (1.0 + tolerance) * global_min_error.

  • Low Tolerance (<0.1): Selects only top matches. Usually more seamless but may cause excessive repetition, repeat source texture as-is, or produce discontinuities if “guided” towards source boundaries.

  • High Tolerance (>0.3): Accepts a broader range of matches. Reduces repetition but can make seams visible if matches are poor.

Note

Because this is relative to global_min_error, tolerance behaviour depends heavily on the source texture content (contrast, pattern complexity, noise). Example ranges are a guideline, not absolute.

2. Patch Layout

Square Patching

In the square implementation, the grid is Cartesian. The block_size and overlap are straightforward pixel values. Each new block is placed at an offset of block_size - overlap from the previous one.

Circular Patching

Circular patches are placed on a Hexagonal Lattice, which provides a more organic distribution.

  • Radius-Based: The geometry is driven by the radius.

  • Spacing Factor: A parameter unique to circular patching that defines the distance between patch centres relative to the radius.

Warning

A spacing factor of 1.12 or lower may result in overlaps that affect the determinism of parallel algorithms.

3. Running with Feathering (No Seams)

By default, the algorithms utilise complex seam-finding (such as A*) to navigate through the overlap and find the path of least resistance. However, a simpler “feathering” approach can be selected.

What is Feathering?

Instead of finding a specific path (a “seam”), feathering applies a smooth gradient mask (vignette) to the overlap area, blending the patches. It is faster and performs well for highly stochastic textures (such as sand or noise) where sharp transitions are less noticeable.

For code examples on how to run synthesis with feathering, see the Quick Start Guide.