[API][Feature] - Add img2img API endpoint

modules/api/api.py

-from modules.api.processing import StableDiffusionProcessingAPI
-from modules.processing import StableDiffusionProcessingTxt2Img, process_images
+from modules.api.processing import StableDiffusionTxt2ImgProcessingAPI, StableDiffusionImg2ImgProcessingAPI
+from modules.processing import StableDiffusionProcessingTxt2Img, StableDiffusionProcessingImg2Img, process_images
 from modules.sd_samplers import all_samplers
 from modules.extras import run_pnginfo
 import modules.shared as shared
@@ -10,6 +10,7 @@ from pydantic import BaseModel, Field, Json
 import json
 import io
 import base64
+from PIL import Image
 
 sampler_to_index = lambda name: next(filter(lambda row: name.lower() == row[1].name.lower(), enumerate(all_samplers)), None)
 
@@ -18,6 +19,11 @@ class TextToImageResponse(BaseModel):
     parameters: Json
     info: Json
 
+class ImageToImageResponse(BaseModel):
+    images: list[str] = Field(default=None, title="Image", description="The generated image in base64 format.")
+    parameters: Json
+    info: Json
+
 
 class Api:
     def __init__(self, app, queue_lock):
@@ -25,8 +31,9 @@ class Api:
         self.app = app
         self.queue_lock = queue_lock
         self.app.add_api_route("/sdapi/v1/txt2img", self.text2imgapi, methods=["POST"])
+        self.app.add_api_route("/sdapi/v1/img2img", self.img2imgapi, methods=["POST"])
 
-    def text2imgapi(self, txt2imgreq: StableDiffusionProcessingAPI ):
+    def text2imgapi(self, txt2imgreq: StableDiffusionTxt2ImgProcessingAPI):
         sampler_index = sampler_to_index(txt2imgreq.sampler_index)
         
         if sampler_index is None:
@@ -54,8 +61,49 @@ class Api:
         
         
 
-    def img2imgapi(self):
-        raise NotImplementedError
+    def img2imgapi(self, img2imgreq: StableDiffusionImg2ImgProcessingAPI):
+        sampler_index = sampler_to_index(img2imgreq.sampler_index)
+        
+        if sampler_index is None:
+            raise HTTPException(status_code=404, detail="Sampler not found") 
+
+
+        init_images = img2imgreq.init_images
+        if init_images is None:
+            raise HTTPException(status_code=404, detail="Init image not found") 
+
+        
+        populate = img2imgreq.copy(update={ # Override __init__ params
+            "sd_model": shared.sd_model, 
+            "sampler_index": sampler_index[0],
+            "do_not_save_samples": True,
+            "do_not_save_grid": True
+            }
+        )
+        p = StableDiffusionProcessingImg2Img(**vars(populate))
+
+        imgs = []
+        for img in init_images:
+            # if has a comma, deal with prefix
+            if "," in img:
+                img = img.split(",")[1]
+            # convert base64 to PIL image
+            img = base64.b64decode(img)
+            img = Image.open(io.BytesIO(img))
+            imgs = [img] * p.batch_size
+
+        p.init_images = imgs
+        # Override object param
+        with self.queue_lock:
+            processed = process_images(p)
+        
+        b64images = []
+        for i in processed.images:
+            buffer = io.BytesIO()
+            i.save(buffer, format="png")
+            b64images.append(base64.b64encode(buffer.getvalue()))
+
+        return ImageToImageResponse(images=b64images, parameters=json.dumps(vars(img2imgreq)), info=json.dumps(processed.info))
 
     def extrasapi(self):
         raise NotImplementedError

modules/api/processing.py

+from array import array
 from inflection import underscore
 from typing import Any, Dict, Optional
 from pydantic import BaseModel, Field, create_model
-from modules.processing import StableDiffusionProcessingTxt2Img
+from modules.processing import StableDiffusionProcessingTxt2Img, StableDiffusionProcessingImg2Img
 import inspect
 
 
@@ -92,8 +93,14 @@ class PydanticModelGenerator:
         DynamicModel.__config__.allow_mutation = True
         return DynamicModel
     
-StableDiffusionProcessingAPI = PydanticModelGenerator(
+StableDiffusionTxt2ImgProcessingAPI = PydanticModelGenerator(
     "StableDiffusionProcessingTxt2Img", 
     StableDiffusionProcessingTxt2Img,
     [{"key": "sampler_index", "type": str, "default": "Euler"}]
+).generate_model()
+
+StableDiffusionImg2ImgProcessingAPI = PydanticModelGenerator(
+    "StableDiffusionProcessingImg2Img", 
+    StableDiffusionProcessingImg2Img,
+    [{"key": "sampler_index", "type": str, "default": "Euler"}, {"key": "init_images", "type": list, "default": None}, {"key": "denoising_strength", "type": float, "default": 0.75}]
 ).generate_model()
\ No newline at end of file

modules/processing.py

@@ -623,7 +623,7 @@ class StableDiffusionProcessingTxt2Img(StableDiffusionProcessing):
 class StableDiffusionProcessingImg2Img(StableDiffusionProcessing):
     sampler = None
 
-    def __init__(self, init_images=None, resize_mode=0, denoising_strength=0.75, mask=None, mask_blur=4, inpainting_fill=0, inpaint_full_res=True, inpaint_full_res_padding=0, inpainting_mask_invert=0, **kwargs):
+    def __init__(self, init_images: list=None, resize_mode: int=0, denoising_strength: float=0.75, mask: str=None, mask_blur: int=4, inpainting_fill: int=0, inpaint_full_res: bool=True, inpaint_full_res_padding: int=0, inpainting_mask_invert: int=0, **kwargs):
         super().__init__(**kwargs)
 
         self.init_images = init_images