feat: add LTX spatial latent upscale hires support (#1533)

examples/server/README.md

@@ -277,6 +277,8 @@ Default Generation Options:
                                            model-specific
   --sigmas                                 custom sigma values for the sampler, comma-separated (e.g.,
                                            "14.61,7.8,3.5,0.0").
+  --hires-sigmas                           custom sigma values for the highres fix second pass, comma-separated (e.g.,
+                                           "0.85,0.725,0.421875,0.0").
   --skip-layers                            layers to skip for SLG steps (default: [7,8,9])
   --high-noise-skip-layers                 (high noise) layers to skip for SLG steps (default: [7,8,9])
   -r, --ref-image                          reference image for Flux Kontext models (can be used multiple times)

examples/server/api.md

@@ -532,6 +532,7 @@ Shared default fields used by both `img_gen` and `vid_gen`:
 | `hires.target_height` | `integer` |
 | `hires.steps` | `integer` |
 | `hires.denoising_strength` | `number` |
+| `hires.custom_sigmas` | `array<number>` |
 | `hires.upscale_tile_size` | `integer` |
 
 `vid_gen`-specific default fields:
@@ -685,6 +686,7 @@ Example:
     "target_height": 0,
     "steps": 0,
     "denoising_strength": 0.7,
+    "custom_sigmas": [],
     "upscale_tile_size": 128
   },
 
@@ -799,6 +801,7 @@ Other native fields:
 | `hires.target_height` | `integer` |
 | `hires.steps` | `integer` |
 | `hires.denoising_strength` | `number` |
+| `hires.custom_sigmas` | `array<number>` |
 | `hires.upscale_tile_size` | `integer` |
 | `vae_tiling_params` | `object` |
 | `cache_mode` | `string` |
@@ -806,7 +809,7 @@ Other native fields:
 | `scm_mask` | `string` |
 | `scm_policy_dynamic` | `boolean` |
 
-For `hires.upscaler`, use `Lanczos`, `Nearest`, `Latent`, `Latent (nearest)`, `Latent (nearest-exact)`, `Latent (antialiased)`, `Latent (bicubic)`, `Latent (bicubic antialiased)`, or an `upscalers[].name` value from `GET /sdcpp/v1/capabilities`. Model-backed upscalers are resolved as `--hires-upscalers-dir / (name + ext)` and must live directly in that directory.
+For `hires.upscaler`, use `Lanczos`, `Nearest`, `Latent`, `Latent (nearest)`, `Latent (nearest-exact)`, `Latent (antialiased)`, `Latent (bicubic)`, `Latent (bicubic antialiased)`, or an `upscalers[].name` value from `GET /sdcpp/v1/capabilities`. Model-backed upscalers are resolved as `--hires-upscalers-dir / (name + ext)` and must live directly in that directory. `hires.custom_sigmas`, when present, overrides the generated second-pass hires sigma schedule; otherwise the hires schedule is trimmed by `hires.denoising_strength`.
 
 HTTP-only output fields:
 

examples/server/routes_sdcpp.cpp

@@ -100,6 +100,20 @@ static json make_sample_params_json(const sd_sample_params_t& sample_params, con
     };
 }
 
+static json make_hires_json(const SDGenerationParams& defaults) {
+    return {
+        {"enabled", defaults.hires_enabled},
+        {"upscaler", defaults.hires_upscaler},
+        {"scale", defaults.hires_scale},
+        {"target_width", defaults.hires_width},
+        {"target_height", defaults.hires_height},
+        {"steps", defaults.hires_steps},
+        {"denoising_strength", defaults.hires_denoising_strength},
+        {"custom_sigmas", defaults.hires_custom_sigmas},
+        {"upscale_tile_size", defaults.hires_upscale_tile_size},
+    };
+}
+
 static json make_img_gen_defaults_json(const SDGenerationParams& defaults, const std::string& output_format) {
     return {
         {"prompt", defaults.prompt},
@@ -114,17 +128,7 @@ static json make_img_gen_defaults_json(const SDGenerationParams& defaults, const
         {"increase_ref_index", defaults.increase_ref_index},
         {"control_strength", defaults.control_strength},
         {"sample_params", make_sample_params_json(defaults.sample_params, defaults.skip_layers)},
-        {"hires",
-         {
-             {"enabled", defaults.hires_enabled},
-             {"upscaler", defaults.hires_upscaler},
-             {"scale", defaults.hires_scale},
-             {"target_width", defaults.hires_width},
-             {"target_height", defaults.hires_height},
-             {"steps", defaults.hires_steps},
-             {"denoising_strength", defaults.hires_denoising_strength},
-             {"upscale_tile_size", defaults.hires_upscale_tile_size},
-         }},
+        {"hires", make_hires_json(defaults)},
         {"vae_tiling_params", make_vae_tiling_json(defaults.vae_tiling_params)},
         {"cache_mode", defaults.cache_mode},
         {"cache_option", defaults.cache_option},
@@ -150,6 +154,7 @@ static json make_vid_gen_defaults_json(const SDGenerationParams& defaults, const
         {"vace_strength", defaults.vace_strength},
         {"sample_params", make_sample_params_json(defaults.sample_params, defaults.skip_layers)},
         {"high_noise_sample_params", make_sample_params_json(defaults.high_noise_sample_params, defaults.high_noise_skip_layers)},
+        {"hires", make_hires_json(defaults)},
         {"vae_tiling_params", make_vae_tiling_json(defaults.vae_tiling_params)},
         {"cache_mode", defaults.cache_mode},
         {"cache_option", defaults.cache_option},