sd_highres_fix: High-resolution image generation (Highres Fix)

In sd2R: Stable Diffusion Image Generation

High-resolution image generation (Highres Fix)

Description

Two-pass generation: first creates a base image at native model resolution, then upscales and refines with tiled img2img to produce a high-resolution result with coherent global composition.

Usage

sd_highres_fix(
  ctx,
  prompt,
  negative_prompt = "",
  width = 2048L,
  height = 2048L,
  sample_method = SAMPLE_METHOD$EULER,
  sample_steps = 20L,
  cfg_scale = 7,
  seed = 42L,
  scheduler = SCHEDULER$DISCRETE,
  clip_skip = -1L,
  eta = 0,
  hr_strength = 0.4,
  hr_steps = NULL,
  sample_tile_size = NULL,
  sample_tile_overlap = 0.25,
  upscaler = NULL,
  upscale_factor = 4L,
  vae_mode = "auto",
  vae_auto_threshold = 1048576L,
  vae_tile_size = 64L,
  vae_tile_overlap = 0.25,
  cache_mode = c("off", "easy", "ucache"),
  cache_config = NULL
)

Arguments

ctx	SD context created by sd_ctx
prompt	Text prompt describing desired image
negative_prompt	Negative prompt (default "")
width	Target output width in pixels (default 2048)
height	Target output height in pixels (default 2048)
sample_method	Sampling method (see SAMPLE_METHOD)
sample_steps	Number of sampling steps (default 20)
cfg_scale	Classifier-free guidance scale (default 7.0)
seed	Random seed (-1 for random)
scheduler	Scheduler type (see SCHEDULER)
clip_skip	Number of CLIP layers to skip (-1 = auto)
eta	Eta parameter for DDIM-like samplers
hr_strength	Denoising strength for the refinement pass (0.0-1.0, default 0.4). Lower = more faithful to base, higher = more detail/change.
hr_steps	Sample steps for refinement pass (default same as sample_steps)
sample_tile_size	Tile size in latent pixels for refinement (default auto)
sample_tile_overlap	Tile overlap fraction (default 0.25)
upscaler	Path to ESRGAN model for upscaling. If NULL, uses bilinear.
upscale_factor	ESRGAN upscale factor (default 4, only used with upscaler)
vae_mode	VAE processing mode: "normal" (no tiling), "tiled" (always tile), or "auto" (VRAM-aware: queries free GPU memory via Vulkan and compares against estimated peak VAE usage; tiles only when VRAM is insufficient). Default "auto".
vae_auto_threshold	Pixel area fallback threshold for vae_mode = "auto" when VRAM query is unavailable (no Vulkan, CPU backend, etc.). Tiling activates when width * height exceeds this value. Default 1048576L (1024x1024 pixels).
vae_tile_size	Tile size in latent pixels for tiled VAE (default 64). Ignored when vae_tile_rel_x/vae_tile_rel_y are set.
vae_tile_overlap	Overlap ratio between tiles, 0.0-0.5 (default 0.25)
cache_mode	Step caching mode: "off" (default), "easy" (EasyCache — skips redundant denoising steps), or "ucache" (UCache). Can speed up sampling 20-40% with minor quality impact.
cache_config	Optional fine-tuned cache config from sd_cache_params. Overrides cache_mode when provided.

Value

SD image (single image, not list)

sd2R documentation built on March 30, 2026, 5:08 p.m.