rs: ratio of reference patches to sample at each step.
T: number of (linear) discretization steps between 0 and 1 to solve the flow ODE.
k: number of top closest patch used to approximate the velocity field.
octaves: number of dyadic scales used for the synthesis.
renoise: "time" $t_r$ used renoise the smooth upsampled image at each resolution: $x_{start}=t_r*x_{upsampled}+(1-t_r)z$. In particular, $t_r=1$ means additional noise.
Blend: mixes the synthesized image with the input image, which can help preserve part of the input image structure.
Blend Alpha: weighting factor for the mix between the synthesized texture and the input image.
Blend Map: if checked, textures will be blended linearly (from right to left, with a mix of both in the middle).
Patch Size: size of the patches used by the algorithm (the larger the patches, the larger the copied areas).
Stride: number of jumps used to compute flow matching (increasing the stride reduces computation time).
Warmup (if Memory is enabled): number of initial steps during which the flow is not applied, which can help stabilize the synthesis at the beginning.
Memory: use the memory-efficient version of Nifty, which does not store all intermediate synthesized images during flow integration, but only the current image.
Seed: random seed (the same seed for a given random process returns the same value; thus, for texture synthesis, the same seed gives the same result if the parameters are identical).
Noise: adds noise during synthesis, which can help escape local minima and produce more diverse results.
Spot Size: size of the spots used for synthesis, relative to the patch size.