Source code for clusex.lib.maskellipse

#! /usr/bin/env python3

# Ellipse masking demo on your sample image.
# Edit the parameters (xc, yc, a, b, theta_deg) to your ellipse.

from PIL import Image
import numpy as np
import matplotlib.pyplot as plt
import re
import argparse
import os
import shutil
import pandas as pd






def maskImage(sexcat, paths, scale, offset, desi_pixscale, 
                image_plate, out_dir):


    if os.path.exists(out_dir):
        shutil.rmtree(out_dir)
        print(f"Deleted: {out_dir}")
    else:
        print("Directory not found. Creating one")

    os.makedirs(out_dir, exist_ok=True)


    df2 = pd.read_csv(sexcat,sep=" ", header=None)


    df1 = pd.read_csv(paths, sep=r"\s+", header=None, names=["path"], engine="python")

    # ID from file name
    df1["ID"] = df1["path"].apply(extrae_id)


    df2.rename(columns={0: "ID"}, inplace=True)

    # 3) join (left join) using ID. It keeps the rows size of df1.
    merged = pd.merge(df1, df2, on="ID", how="left", sort=False)

    # 4) sort columns in this order: path, clas, ID and the rest
    otras_cols = [c for c in merged.columns if c not in ["path",  "ID"]]
    merged = merged[["path", "ID"] + otras_cols]



    #columns X_new y Y_new for RA y DEC
    img_paths =  merged.iloc[:,0]
    numbers = merged.iloc[:,1]
    X = merged.iloc[:,4]
    Y = merged.iloc[:,5]
    krons = merged.iloc[:,7]
    Ais = merged.iloc[:,10]
    Es = merged.iloc[:,11]
    Thetas = merged.iloc[:,12]

    Thetas = Thetas*(-1) # for conversion from Sextractor

    Rkrons = scale*Ais*krons + offset

    Rkrons = Rkrons * image_plate / desi_pixscale #modifying scale from original to DESI

    Rkronsb = Rkrons*(1-Es)

    ################

    # Load example image placed at /mnt/data by the system message
    #img_path = "desi_images/imagen_0006.png"


    for idx, (img_path, number, a, b, theta_deg) in enumerate(zip(img_paths, numbers, Rkrons, Rkronsb, Thetas)):

        outimage = applyMask(img_path, number , a, b, theta_deg, out_dir)






def applyMask(img_path, number , a, b, theta_deg, outdir):
   
    # Load example image placed at /mnt/data by the system message
    #img_path = "desi_images/imagen_0006.png"
    im = Image.open(img_path).convert("RGB")
    arr = np.array(im)

    h, w, _ = arr.shape
    
    # ---- Ellipse parameters (in pixels) ---
    xc, yc = w/2, h/2

    theta = np.deg2rad(theta_deg)
    
    # Create coordinate grid
    y, x = np.mgrid[0:h, 0:w]
    x_shift = x - xc
    y_shift = y - yc
   
    # Rotate coordinates (clockwise rotation of the ellipse frame)
    cos_t, sin_t = np.cos(theta), np.sin(theta)
    xr =  x_shift * cos_t + y_shift * sin_t
    yr = -x_shift * sin_t + y_shift * cos_t
    
    # Ellipse implicit equation: (xr/a)^2 + (yr/b)^2 <= 1
    mask_inside = (xr/a)**2 + (yr/b)**2 <= 1.0
    
    # Apply mask: keep inside ellipse, set outside to black
    clean = arr.copy()
    clean[~mask_inside] = 0
    
    # Save result
    #out_path = "imagen_0006_masked.png"

    out_path = os.path.join(outdir, f"imagen_{number:04d}.png")

    Image.fromarray(clean).save(out_path)
    
    return(out_path)








def extrae_id(path: str) -> int:
    """
    Extract ID number from file path  imagen_0004.png -> 4.
    returns ValueError if number is not found
    """
    m = re.search(r'(\d+)\.png$', path.strip())
    if not m:
        raise ValueError(f"ID can not be extracted from: {path}")
    return int(m.group(1).lstrip("0") or "0")