main.py

from fastapi import FastAPI, File, UploadFile
from fastapi.responses import StreamingResponse
import numpy as np
import cv2
import io
from PIL import Image

# Load the models
print("Loading models...")
net = cv2.dnn.readNetFromCaffe('colorization_deploy_v2.prototxt', 'colorization_release_v2.caffemodel')
pts = np.load('pts_in_hull.npy')

class8 = net.getLayerId("class8_ab")
conv8 = net.getLayerId("conv8_313_rh")
pts = pts.transpose().reshape(2, 313, 1, 1)

net.getLayer(class8).blobs = [pts.astype("float32")]
net.getLayer(conv8).blobs = [np.full([1, 313], 2.606, dtype='float32')]

# Initialize FastAPI app
app = FastAPI()

def read_image(file):
    # Open the image with Pillow
    pil_image = Image.open(file)

    # Convert the Pillow image to a NumPy array
    image_array = np.array(pil_image)

    return image_array

def colorize_image(image):
    # Convert the PIL image to OpenCV format
    image = np.array(image)
    image = cv2.cvtColor(image, cv2.COLOR_RGB2BGR)
    
    scaled = image.astype("float32") / 255.0
    lab = cv2.cvtColor(scaled, cv2.COLOR_BGR2LAB)

    resized = cv2.resize(lab, (224, 224))
    L = cv2.split(resized)[0]
    L -= 50

    net.setInput(cv2.dnn.blobFromImage(L))
    ab = net.forward()[0, :, :, :].transpose((1, 2, 0))
    ab = cv2.resize(ab, (image.shape[1], image.shape[0]))

    L = cv2.split(lab)[0]
    colorized = np.concatenate((L[:, :, np.newaxis], ab), axis=2)
    colorized = cv2.cvtColor(colorized, cv2.COLOR_LAB2RGB)
    colorized = np.clip(colorized, 0, 1)
    colorized = (255 * colorized).astype("uint8")

    return colorized

@app.post("/upload/")
async def upload(file: UploadFile = File(...)):
    # Read the image using Pillow and convert to NumPy array
    image_array = read_image(file.file)
    
    # Process the image
    colorized_image = colorize_image(image_array)

    # Convert the colorized image to bytes
    pil_image = Image.fromarray(colorized_image)
    buf = io.BytesIO()
    pil_image.save(buf, format="PNG")
    buf.seek(0)

    return StreamingResponse(buf, media_type="image/png")