app.py

import gradio as gr
import fastai.vision.all as fv
from PIL import Image, ImageDraw
import skimage

learn = fv.load_learner("model.pkl")

def call(image, step_size:int=100, blocks:int=4):
  # print(image)
  original_image = Image.fromarray(image).resize((400,400))

  image = Image.new(mode='RGB', size=(step_size*blocks, step_size*blocks)) #, color=255
  
  draw = ImageDraw.Draw(image)
  for (x,y) in [ (x,y) for x in range(0, blocks * step_size, step_size) for y in range(0, blocks * step_size, step_size)]:
    cropped_image = original_image.crop((x, y, x+step_size, y+step_size))
    image.paste(cropped_image, (x,y))
    prediction = learn.predict(cropped_image)
    print(prediction)
    marker = f"{prediction[0][0].upper()} {prediction[2][prediction[1].item()].item()*100:.0f}"
    position = (x+10, y+10)
    
    bbox = draw.textbbox(position, marker, font=None)
    draw.rectangle(bbox, fill="white")
    draw.text(position, marker, font=None, fill="black")

  draw = ImageDraw.Draw(image)
  for x in range(0, blocks * step_size, step_size):
    # vertical line
    line = ((x, 0), (x, blocks * step_size))
    draw.line(line, fill=128, width=3)

    # horizontal line
    line = ((0, x), (blocks * step_size, x))
    draw.line(line, fill=128, width=3)
  
  return image


title = "Traffic Light Detector"
description = "Experiment traffic light detection to evaluate the value of captcha security controls"

iface = gr.Interface(fn=call, inputs="image", outputs="image", title=title, description=description)
iface.launch()