Move preserved header list, drop sBIT

src/headers.rs

@@ -69,7 +69,7 @@ pub enum Headers {
     None,
     /// Remove specific chunks
     Strip(Vec<String>),
-    /// Headers that won't affect rendering (all but cICP, iCCP, sBIT, sRGB, pHYs)
+    /// Remove all chunks that won't affect rendering
     Safe,
     /// Remove all non-critical chunks except these
     Keep(IndexSet<String>),
@@ -77,6 +77,11 @@ pub enum Headers {
     All,
 }
 
+impl Headers {
+    /// List of chunks that will be kept when using the `Safe` option
+    pub const KEEP_SAFE: [[u8; 4]; 4] = [*b"cICP", *b"iCCP", *b"sRGB", *b"pHYs"];
+}
+
 #[inline]
 pub fn file_header_is_valid(bytes: &[u8]) -> bool {
     let expected_header: [u8; 8] = [0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A];

src/lib.rs

@@ -881,16 +881,9 @@ fn perform_strip(png: &mut PngData, opts: &Options) {
                 raw.aux_headers.remove(hdr.as_bytes());
             }
         }
-        Headers::Safe => {
-            const PRESERVED_HEADERS: [[u8; 4]; 5] =
-                [*b"cICP", *b"iCCP", *b"sBIT", *b"sRGB", *b"pHYs"];
-            let keys: Vec<[u8; 4]> = raw.aux_headers.keys().cloned().collect();
-            for hdr in &keys {
-                if !PRESERVED_HEADERS.contains(hdr) {
-                    raw.aux_headers.remove(hdr);
-                }
-            }
-        }
+        Headers::Safe => raw
+            .aux_headers
+            .retain(|hdr, _| Headers::KEEP_SAFE.contains(hdr)),
         Headers::All => {
             raw.aux_headers = IndexMap::new();
         }