feat(api): add linear blend stage for chain pipeline (#183)

api/onnx_web/chain/__init__.py

@@ -1,6 +1,7 @@
 from .base import ChainPipeline, PipelineStage, StageCallback, StageParams
 from .blend_img2img import blend_img2img
 from .blend_inpaint import blend_inpaint
+from .blend_linear import blend_linear
 from .blend_mask import blend_mask
 from .correct_codeformer import correct_codeformer
 from .correct_gfpgan import correct_gfpgan
@@ -21,6 +22,7 @@
 CHAIN_STAGES = {
     "blend-img2img": blend_img2img,
     "blend-inpaint": blend_inpaint,
+    "blend-linear": blend_linear,
     "blend-mask": blend_mask,
     "correct-codeformer": correct_codeformer,
     "correct-gfpgan": correct_gfpgan,

api/onnx_web/chain/blend_linear.py

@@ -0,0 +1,29 @@
+from logging import getLogger
+from typing import List, Optional
+
+from PIL import Image
+
+from ..image import valid_image
+from ..params import ImageParams, StageParams
+from ..server import ServerContext
+from ..worker import ProgressCallback, WorkerContext
+
+logger = getLogger(__name__)
+
+
+def blend_linear(
+    _job: WorkerContext,
+    _server: ServerContext,
+    _stage: StageParams,
+    _params: ImageParams,
+    *,
+    alpha: float,
+    sources: Optional[List[Image.Image]] = None,
+    _callback: Optional[ProgressCallback] = None,
+    **kwargs,
+) -> Image.Image:
+    logger.info("blending image using linear interpolation")
+
+    resized = [valid_image(s) for s in sources]
+
+    return Image.blend(resized[1], resized[0], alpha)