fix(exr): improve attribute translation rules (#4946)

In exr output, we were doing attribute name substitutions using
case-insensitive comparisions, whereas on the exr input side, we were
using case-sensitive comparisons. This was leading to some strange
behavior where certain attributes were not properly "round tripping"
when reading and writing exr files, particularly when it involved
attribute names that differed only in case from certain
reserved/standard names.

Also be a little more flexible in adjusting exr attributes that have the
wrong type, by being able to convert int or float to a value that's
required to be a string.

Signed-off-by: Larry Gritz <[email protected]>

Author: lgritz

src/openexr.imageio/exroutput.cpp

@@ -1140,8 +1140,7 @@ OpenEXROutput::put_parameter(const std::string& name, TypeDesc type,
     TypeDesc exrtype  = TypeUnknown;
 
     for (const auto& e : exr_meta_translation) {
-        if (Strutil::iequals(xname, e.oiioname)
-            || (e.exrname && Strutil::iequals(xname, e.exrname))) {
+        if (xname == e.oiioname || (e.exrname && xname == e.exrname)) {
             xname   = std::string(e.exrname ? e.exrname : "");
             exrtype = e.exrtype;
             // std::cerr << "exr put '" << name << "' -> '" << xname << "'\n";
@@ -1267,6 +1266,7 @@ OpenEXROutput::put_parameter(const std::string& name, TypeDesc type,
     // OpenEXR expects, and we can make a good guess about how to translate.
     float tmpfloat;
     int tmpint;
+    ustring tmpstring;
     if (exrtype == TypeFloat && type == TypeInt) {
         tmpfloat = float(*(const int*)data);
         data     = &tmpfloat;
@@ -1278,10 +1278,19 @@ OpenEXROutput::put_parameter(const std::string& name, TypeDesc type,
     } else if (exrtype == TypeMatrix && type == TypeDesc(TypeDesc::FLOAT, 16)) {
         // Automatically translate float[16] to Matrix when expected
         type = TypeMatrix;
+    } else if (exrtype == TypeString && type == TypeFloat) {
+        tmpstring = ustring::fmtformat("{}", *(const float*)data);
+        data      = &tmpstring;
+        type      = TypeString;
+    } else if (exrtype == TypeString && type == TypeInt) {
+        tmpstring = ustring::fmtformat("{}", *(const int*)data);
+        data      = &tmpstring;
+        type      = TypeString;
     }
 
     // Now if we still don't match a specific type OpenEXR is looking for,
-    // skip it.
+    // skip it. If we ever support warnings for ImageOutput, we should make
+    // this a warning.
     if (exrtype != TypeDesc() && !exrtype.equivalent(type)) {
         OIIO::debugfmt(
             "OpenEXR output metadata \"{}\" type mismatch: expected {}, got {}\n",