Merge pull request #11132 from rouault/jpegxl_read_float16

JPEGXL: add support for reading Float16 (as Float32)
OSGeo · Nov 4, 2024 · 38151bc · 38151bc
2 parents af82417 + e845e53
commit 38151bc
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diff --git a/autotest/gdrivers/data/jpegxl/float16.jxl b/autotest/gdrivers/data/jpegxl/float16.jxl
diff --git a/autotest/gdrivers/jpegxl.py b/autotest/gdrivers/jpegxl.py
@@ -847,3 +847,17 @@ def test_jpegxl_identify_raw_codestream():
         f"{gdalmanage_path} identify data/jpegxl/test.jxl.bin"
     )
     assert "JPEGXL" in out
+
+
+###############################################################################
+def test_jpegxl_read_float16():
+
+    # Image produced with:
+    # gdal_translate autotest/gcore/data/rgbsmall.tif float.exr -co PIXEL_TYPE=FLOAT -co TILED=NO -co COMPRESS=PIZ
+    # cjxl -d 0 float.exr float16.jxl
+    ds = gdal.Open("data/jpegxl/float16.jxl")
+    assert [ds.GetRasterBand(i + 1).Checksum() for i in range(3)] == [
+        21212,
+        21053,
+        21349,
+    ]
diff --git a/frmts/jpegxl/jpegxl.cpp b/frmts/jpegxl/jpegxl.cpp
@@ -475,6 +475,12 @@ bool JPEGXLDataset::Open(GDALOpenInfo *poOpenInfo)
                 else if (info.bits_per_sample <= 16)
                     eDT = GDT_UInt16;
             }
+            else if (info.exponent_bits_per_sample == 5)
+            {
+                // Float16
+                CPLDebug("JXL", "16-bit floating point data");
+                eDT = GDT_Float32;
+            }
             else if (info.exponent_bits_per_sample == 8)
             {
                 eDT = GDT_Float32;