Add an opt-in to skip Instagram's exact resolution requirement

Some users want the assembled HDR JPEG for somewhere other than
Instagram, where the exact 1080x1080/1080x1350/1080x566 match isn't
relevant. A checkbox on the form now lets the whole batch skip that
specific check. The SDR/HDR dimension-match check still always
applies, since that's a technical requirement for the gain map to
align, not an Instagram-specific rule.

app/routes.py

@@ -8,7 +8,7 @@ from flask import abort, redirect, render_template, request, send_file, url_for
 from . import assembler, jobs, validation
 
 
-def _process_pair(job_dir, index, sdr_file, hdr_file):
+def _process_pair(job_dir, index, sdr_file, hdr_file, ignore_ig_resolution=False):
     """Runs one SDR/HDR pair through validation + assembly. Returns an item
     dict for the job report; never raises — failures are recorded in it."""
     name = hdr_file.filename or sdr_file.filename or f"pair {index}"
@@ -28,7 +28,7 @@ def _process_pair(job_dir, index, sdr_file, hdr_file):
     sdr_file.save(sdr_path)
     hdr_file.save(hdr_path)
 
-    ig_error = validation.instagram_resolution_error(sdr_path, hdr_path)
+    ig_error = validation.instagram_resolution_error(sdr_path, hdr_path, ignore_ig_resolution)
     if ig_error:
         for p in (sdr_path, hdr_path):
             p.unlink(missing_ok=True)
@@ -62,11 +62,13 @@ def register_routes(app):
         if len(sdr_files) != len(hdr_files):
             return render_template("index.html", error="Each pair needs both an SDR and an HDR file."), 400
 
+        ignore_ig_resolution = request.form.get("ignore_ig_resolution") == "on"
+
         job_id = uuid.uuid4().hex[:12]
         job_dir = jobs.new_job_dir(job_id)
 
         items = [
-            _process_pair(job_dir, i, sdr_file, hdr_file)
+            _process_pair(job_dir, i, sdr_file, hdr_file, ignore_ig_resolution)
             for i, (sdr_file, hdr_file) in enumerate(zip(sdr_files, hdr_files), start=1)
         ]
 

app/validation.py

@@ -42,9 +42,17 @@ def probe_dimensions(path: Path) -> tuple[int, int]:
         raise ValueError(f"could not read image dimensions ({e})") from e
 
 
-def instagram_resolution_error(sdr_path: Path, hdr_path: Path) -> str | None:
+def instagram_resolution_error(
+    sdr_path: Path, hdr_path: Path, ignore_ig_resolution: bool = False,
+) -> str | None:
     """Returns an error message if the pair doesn't meet Instagram's feed
-    requirements, otherwise None."""
+    requirements, otherwise None.
+
+    The dimension-match check always applies: mismatched SDR/HDR
+    dimensions misalign the gain map regardless of what platform the
+    result is for. ignore_ig_resolution skips only the exact-match check
+    against Instagram's own feed resolutions, for results meant for
+    somewhere other than Instagram."""
     try:
         sdr_w, sdr_h = probe_dimensions(sdr_path)
         hdr_w, hdr_h = probe_dimensions(hdr_path)
@@ -57,7 +65,7 @@ def instagram_resolution_error(sdr_path: Path, hdr_path: Path) -> str | None:
             "dimensions, otherwise the gain map will misalign."
         )
 
-    if (sdr_w, sdr_h) not in IG_RESOLUTIONS:
+    if not ignore_ig_resolution and (sdr_w, sdr_h) not in IG_RESOLUTIONS:
         allowed = ", ".join(f"{w}x{h} ({label})" for (w, h), label in IG_RESOLUTIONS.items())
         return f"Image is {sdr_w}x{sdr_h} — Instagram requires an exact match to one of: {allowed}."