From f5dd0ed2db311e60fcd7241a92bb60df37e21683 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Sat, 12 Sep 2026 15:41:27 +1000
Subject: [PATCH 1/3] Return 0 or -1 from ImagingSplit(), rather than number of
 bands

---
 src/_imaging.c         | 2 +-
 src/libImaging/Bands.c | 8 ++++----
 2 files changed, 5 insertions(+), 5 deletions(-)

diff --git a/src/_imaging.c b/src/_imaging.c
index 7e9c0e391c8..ada8c594b5c 100644
--- a/src/_imaging.c
+++ b/src/_imaging.c
@@ -2504,7 +2504,7 @@ _split(ImagingObject *self, PyObject *args) {
     PyObject *imaging_object;
     Imaging bands[4] = {NULL, NULL, NULL, NULL};
 
-    if (!ImagingSplit(self->image, bands)) {
+    if (ImagingSplit(self->image, bands)) {
         return NULL;
     }
 
diff --git a/src/libImaging/Bands.c b/src/libImaging/Bands.c
index d1fa16addff..92999a5ddd8 100644
--- a/src/libImaging/Bands.c
+++ b/src/libImaging/Bands.c
@@ -75,13 +75,13 @@ ImagingSplit(Imaging imIn, Imaging bands[4]) {
     /* Check arguments */
     if (!imIn || imIn->type != IMAGING_TYPE_UINT8) {
         (void)ImagingError_ModeError();
-        return 0;
+        return -1;
     }
 
     /* Shortcuts */
     if (imIn->bands == 1) {
         bands[0] = ImagingCopy(imIn);
-        return imIn->bands;
+        return 0;
     }
 
     for (i = 0; i < imIn->bands; i++) {
@@ -90,7 +90,7 @@ ImagingSplit(Imaging imIn, Imaging bands[4]) {
             for (j = 0; j < i; ++j) {
                 ImagingDelete(bands[j]);
             }
-            return 0;
+            return -1;
         }
     }
 
@@ -170,7 +170,7 @@ ImagingSplit(Imaging imIn, Imaging bands[4]) {
         }
     }
 
-    return imIn->bands;
+    return 0;
 }
 
 Imaging

From ec9eeddfd10ba90114f641a867451872aa6e186a Mon Sep 17 00:00:00 2001
From: Andrew Murray <3112309+radarhere@users.noreply.github.com>
Date: Mon, 14 Sep 2026 11:01:27 +1000
Subject: [PATCH 2/3] Add comments

Co-authored-by: Aarni Koskela <akx@iki.fi>
---
 src/libImaging/Bands.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/src/libImaging/Bands.c b/src/libImaging/Bands.c
index 92999a5ddd8..c6ea81bfa69 100644
--- a/src/libImaging/Bands.c
+++ b/src/libImaging/Bands.c
@@ -68,6 +68,13 @@ ImagingGetBand(Imaging imIn, int band) {
     return imOut;
 }
 
+int
+/**
+ * Splits an image into its component bands.
+ * @param imIn The input image.
+ * @param bands An array of pointers to the output band images.
+ * @return -1 in case of an error, 0 otherwise.
+ */
 int
 ImagingSplit(Imaging imIn, Imaging bands[4]) {
     int i, j, x, y;

From e7d4b1e48d2c03a76d7d60b4463113e91b1b5a20 Mon Sep 17 00:00:00 2001
From: Andrew Murray <radarhere@users.noreply.github.com>
Date: Mon, 14 Sep 2026 11:06:34 +1000
Subject: [PATCH 3/3] Pointers passed in should be null

---
 src/libImaging/Bands.c | 8 ++++----
 1 file changed, 4 insertions(+), 4 deletions(-)

diff --git a/src/libImaging/Bands.c b/src/libImaging/Bands.c
index c6ea81bfa69..410b722bde4 100644
--- a/src/libImaging/Bands.c
+++ b/src/libImaging/Bands.c
@@ -68,12 +68,12 @@ ImagingGetBand(Imaging imIn, int band) {
     return imOut;
 }
 
-int
 /**
  * Splits an image into its component bands.
- * @param imIn The input image.
- * @param bands An array of pointers to the output band images.
- * @return -1 in case of an error, 0 otherwise.
+ *
+ * @param imIn  The input image.
+ * @param bands An array of null pointers to the output band images.
+ * @return      -1 in case of an error, 0 otherwise.
  */
 int
 ImagingSplit(Imaging imIn, Imaging bands[4]) {