Crops to rowing machine screen - can be trained with optimize_crop.py and screen_classifier

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2026-03-16 13:46:02 +00:00
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4 changed files with 309 additions and 31 deletions

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"""
Optimize crop_to_screen.py parameters using Optuna.
Uses the feature-based classifier from screen_classifier.py as the
evaluation function. For each trial, runs find_screen() with suggested
parameters on all source photos and counts how many crops are classified
as rowing displays (label=1). Optuna maximises this count.
Usage:
python optimize_crop.py [--n-trials 300] [--photos-dir photos/]
"""
import argparse
import glob
import os
import tempfile
import cv2
import numpy as np
import optuna
from screen_classifier import cnn_predict
def find_screen_parameterized(image, params):
"""
Detect the Concept 2 PM5 LCD screen region in the image.
Same logic as crop_to_screen.find_screen but with tunable parameters.
Returns (x, y, w, h) bounding box or None if not found.
"""
h_img, w_img = image.shape[:2]
gray = cv2.cvtColor(image, cv2.COLOR_BGR2GRAY)
gk = params["gaussian_kernel_size"]
blurred = cv2.GaussianBlur(gray, (gk, gk), 0)
edges = cv2.Canny(blurred, params["canny_low"], params["canny_high"])
candidates = []
for thresh_val in range(params["thresh_min"], params["thresh_max"], 10):
_, thresh = cv2.threshold(gray, thresh_val, 255, cv2.THRESH_BINARY)
mk = params["morph_kernel_size"]
kern = cv2.getStructuringElement(cv2.MORPH_RECT, (mk, mk))
thresh = cv2.morphologyEx(thresh, cv2.MORPH_CLOSE, kern)
thresh = cv2.morphologyEx(thresh, cv2.MORPH_OPEN, kern)
contours, _ = cv2.findContours(
thresh, cv2.RETR_EXTERNAL, cv2.CHAIN_APPROX_SIMPLE
)
for cnt in contours:
x, y, w, h = cv2.boundingRect(cnt)
area = cv2.contourArea(cnt)
rect_area = w * h
if rect_area == 0:
continue
area_ratio = rect_area / (h_img * w_img)
if (
area_ratio < params["area_ratio_min"]
or area_ratio > params["area_ratio_max"]
):
continue
aspect = w / h
if aspect < params["aspect_min"] or aspect > params["aspect_max"]:
continue
rectangularity = area / rect_area
if rectangularity < params["rectangularity_min"]:
continue
roi_edges = edges[y : y + h, x : x + w]
edge_density = np.sum(roi_edges > 0) / rect_area
if edge_density < params["edge_density_min"]:
continue
score = edge_density * area * rectangularity
candidates.append((score, x, y, w, h))
if not candidates:
return None
candidates.sort(key=lambda c: c[0], reverse=True)
return candidates[0][1:]
def load_images(photos_dir):
"""Load all source images once for reuse across trials."""
paths = sorted(
glob.glob(os.path.join(photos_dir, "*.JPEG"))
+ glob.glob(os.path.join(photos_dir, "*.jpeg"))
+ glob.glob(os.path.join(photos_dir, "*.jpg"))
+ glob.glob(os.path.join(photos_dir, "*.JPG"))
)
images = []
for p in paths:
img = cv2.imread(p)
if img is not None:
images.append((p, img))
return images
def make_objective(images, tmp_dir, model_path):
"""Create an Optuna objective function closed over images and tmp_dir."""
def objective(trial):
params = {
"thresh_min": trial.suggest_int("thresh_min", 60, 160, step=10),
"thresh_max": trial.suggest_int("thresh_max", 160, 255, step=10),
"morph_kernel_size": trial.suggest_int("morph_kernel_size", 3, 21, step=2),
"gaussian_kernel_size": trial.suggest_int(
"gaussian_kernel_size", 3, 11, step=2
),
"canny_low": trial.suggest_int("canny_low", 20, 100, step=10),
"canny_high": trial.suggest_int("canny_high", 100, 250, step=10),
"area_ratio_min": trial.suggest_float("area_ratio_min", 0.001, 0.02),
"area_ratio_max": trial.suggest_float("area_ratio_max", 0.05, 0.30),
"aspect_min": trial.suggest_float("aspect_min", 0.3, 0.8),
"aspect_max": trial.suggest_float("aspect_max", 1.2, 2.5),
"rectangularity_min": trial.suggest_float("rectangularity_min", 0.2, 0.7),
"edge_density_min": trial.suggest_float("edge_density_min", 0.005, 0.06),
}
# Ensure thresh_min < thresh_max
if params["thresh_min"] >= params["thresh_max"]:
return 0
# Ensure canny_low < canny_high
if params["canny_low"] >= params["canny_high"]:
return 0
rowing_count = 0
for img_path, img in images:
result = find_screen_parameterized(img, params)
if result is None:
continue
x, y, w, h = result
h_img, w_img = img.shape[:2]
padding = 15
x1 = max(0, x - padding)
y1 = max(0, y - padding)
x2 = min(w_img, x + w + padding)
y2 = min(h_img, y + h + padding)
cropped = img[y1:y2, x1:x2]
# Save to temp file for the classifier
basename = os.path.splitext(os.path.basename(img_path))[0]
tmp_path = os.path.join(tmp_dir, f"{basename}_trial{trial.number}.jpg")
cv2.imwrite(tmp_path, cropped, [cv2.IMWRITE_JPEG_QUALITY, 95])
try:
label, _ = cnn_predict(tmp_path, model_path)
if label == 1:
rowing_count += 1
finally:
# Clean up immediately to save disk space
if os.path.exists(tmp_path):
os.remove(tmp_path)
return rowing_count
return objective
def main():
parser = argparse.ArgumentParser(
description="Optimize crop_to_screen.py parameters"
)
parser.add_argument(
"--photos-dir", default="photos/", help="Directory of source photos"
)
parser.add_argument(
"--n-trials", type=int, default=300, help="Number of Optuna trials"
)
parser.add_argument(
"--model-path",
default="screen_classifier_model.pth",
help="Path to CNN model weights",
)
args = parser.parse_args()
images = load_images(args.photos_dir)
print(f"Loaded {len(images)} source images from {args.photos_dir}")
with tempfile.TemporaryDirectory() as tmp_dir:
study = optuna.create_study(direction="maximize")
objective = make_objective(images, tmp_dir, args.model_path)
study.optimize(objective, n_trials=args.n_trials, show_progress_bar=True)
print(f"\n{'=' * 60}")
print(f"Best score: {study.best_value} / {len(images)} images classified as rowing")
print(f"Best parameters:")
for k, v in sorted(study.best_params.items()):
print(f" {k:>25s}: {v}")
print(f"{'=' * 60}")
if __name__ == "__main__":
main()