Write modified images from dl1ab in output DL1 files and fix add_config_metadata

lstchain/scripts/lstchain_dl1ab.py

@@ -15,6 +15,7 @@
 import argparse
 import logging
 from pathlib import Path
+import json
 
 import astropy.units as u
 import numpy as np
@@ -92,6 +93,27 @@
 )
 
 
+def image_modifier_checker(config):
+    """
+    Check if the image modifier has been used in the given configuration.
+
+    Parameters
+    ----------
+    config : `dict`
+        The configuration dictionary to check.
+
+    Returns
+    -------
+    `bool`
+        `True` if the image modifier has been used, `False` otherwise.
+    """
+    imconfig = config.get('image_modifier', {})
+    increase_nsb = imconfig.get("increase_nsb", False)
+    increase_psf = imconfig.get("increase_psf", False)
+
+    return increase_nsb or increase_psf
+
+
 def main():
     args = parser.parse_args()
 
@@ -149,7 +171,7 @@
     if increase_nsb or increase_psf:
         log.info(f"image_modifier configuration: {imconfig}")
         if not args.no_image:
             log.info("Modified images are saved in the output file.")
 
     if increase_nsb:
         extra_noise_in_dim_pixels = imconfig["extra_noise_in_dim_pixels"]
@@ -243,6 +265,13 @@
 
     with tables.open_file(args.input_file, mode='r') as infile:
         image_table = read_table(infile, dl1_images_lstcam_key)
+        # if the image modifier has been used to produce these images, stop here
+        config_from_image_table = json.loads(image_table.meta['config'])
+        if image_modifier_checker(config_from_image_table) and image_modifier_checker(config):
+            log.error(f"The image modifier has already been used to produce the images in file {args.input_file}."
+                        "Re-applying the image modifier is not a good practice, start again from unmodified images please.")
+            sys.exit(0)
+
         images = image_table['image']
         params = read_table(infile, dl1_params_lstcam_key)
         dl1_params_input = params.colnames

lstchain/scripts/tests/test_dl1ab.py

@@ -0,0 +1,23 @@
+from lstchain.scripts.lstchain_dl1ab import image_modifier_checker
+
+
+def test_image_modifier_checker_no_modifiers():
+    config = {}
+    assert not image_modifier_checker(config)
+
+
+def test_image_modifier_checker_empty_modifier():
+    config = {"image_modifier": {}}
+    assert not image_modifier_checker(config)
+
+
+def test_image_modifier_checker_with_modifiers():
+    config = {"image_modifier": {"increase_psf": True, "increase_nsb": False}}
+    assert image_modifier_checker(config)
+    config = {"image_modifier": {"increase_nsb": True, "increase_psf": False}}
+    assert image_modifier_checker(config)
+    config = {"image_modifier": {"increase_psf": True, "increase_nsb": True}}
+    assert image_modifier_checker(config)
+    config = {"image_modifier": {"increase_psf": False, "increase_nsb": False}}
+    assert not image_modifier_checker(config)
+

lstchain/scripts/tests/test_lstchain_scripts.py

@@ -430,6 +430,24 @@ def test_dl1ab_no_images(simulated_dl1_file, tmp_path):
             assert (new_parameters['length'] != old_parameters['length']).any()
 
 
+@pytest.mark.xfail(raises=ValueError, reason="One should not be able to re-modify already modified images")
+def test_dl1ab_on_modified_images(simulated_dl1ab, tmp_path):
+    config_path = tmp_path / 'config.json'
+    output_file = tmp_path / 'dl1ab_on_modified_images.h5'
+    with config_path.open('w') as f:
+        config = get_standard_config()
+        config['image_modifier'] = {'increase_psf': True, 'increase_nsb': True}
+        json.dump(config, f)
+
+    run_program(
+        'lstchain_dl1ab',
+        '-f', simulated_dl1ab,
+        '-o', output_file,
+        '-c', config_path,
+        '--no-image',
+    )
+
+
 @pytest.mark.private_data
 def test_observed_dl1ab(tmp_path, observed_dl1_files):
     output_dl1ab = tmp_path / "dl1ab.h5"