Merge pull request #9403 from rouault/fix_9402

gdal_translate -expand rgb[a]: automatically select Byte output data …
OSGeo · Mar 11, 2024 · 48227ca · 48227ca
2 parents ccad35a + a8134aa
commit 48227ca
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Showing 2 changed files with 66 additions and 2 deletions.
diff --git a/apps/gdal_translate_lib.cpp b/apps/gdal_translate_lib.cpp
@@ -1917,6 +1917,8 @@ GDALDatasetH GDALTranslate(const char *pszDest, GDALDatasetH hSrcDataset,
     /* ==================================================================== */
     /*      Process all bands.                                              */
     /* ==================================================================== */
+    GDALDataType eOutputType = psOptions->eOutputType;
+
     for (int i = 0; i < psOptions->nBandCount; i++)
     {
         int nComponent = 0;
@@ -1947,13 +1949,44 @@ GDALDatasetH GDALTranslate(const char *pszDest, GDALDatasetH hSrcDataset,
         GDALRasterBand *poRealSrcBand =
             (nSrcBand < 0) ? poSrcBand->GetMaskBand() : poSrcBand;
         GDALDataType eBandType;
-        if (psOptions->eOutputType == GDT_Unknown)
+        if (eOutputType == GDT_Unknown)
         {
             eBandType = poRealSrcBand->GetRasterDataType();
+            if (eBandType != GDT_Byte && psOptions->nRGBExpand != 0)
+            {
+                // Use case of https://github.com/OSGeo/gdal/issues/9402
+                if (const auto poColorTable = poRealSrcBand->GetColorTable())
+                {
+                    bool bIn0To255Range = true;
+                    const int nColorCount = poColorTable->GetColorEntryCount();
+                    for (int nColor = 0; nColor < nColorCount; nColor++)
+                    {
+                        const GDALColorEntry *poEntry =
+                            poColorTable->GetColorEntry(nColor);
+                        if (poEntry->c1 > 255 || poEntry->c2 > 255 ||
+                            poEntry->c3 > 255 || poEntry->c4 > 255)
+                        {
+                            bIn0To255Range = false;
+                            break;
+                        }
+                    }
+                    if (bIn0To255Range)
+                    {
+                        if (!psOptions->bQuiet)
+                        {
+                            CPLError(CE_Warning, CPLE_AppDefined,
+                                     "Using Byte output data type due to range "
+                                     "of values in color table");
+                        }
+                        eBandType = GDT_Byte;
+                    }
+                }
+                eOutputType = eBandType;
+            }
         }
         else
         {
-            eBandType = psOptions->eOutputType;
+            eBandType = eOutputType;
 
             // Check that we can copy existing statistics
             GDALDataType eSrcBandType = poRealSrcBand->GetRasterDataType();

diff --git a/autotest/utilities/test_gdal_translate_lib.py b/autotest/utilities/test_gdal_translate_lib.py
@@ -1249,3 +1249,34 @@ def test_gdal_translate_ovr_rpc():
     assert float(ovr_rpc["SAMP_SCALE"]) == pytest.approx(
         0.5 * float(src_rpc["SAMP_SCALE"])
     )
+
+
+###############################################################################
+# Test scenario of https://github.com/OSGeo/gdal/issues/9402
+
+
+def test_gdal_translate_lib_raster_uint16_ct_0_255_range():
+
+    for (r, g, b, a) in [
+        (255 + 1, 255, 255, 255),
+        (255, 255 + 1, 255, 255),
+        (255, 255, 255 + 1, 255),
+        (255, 255, 255, 255 + 1),
+    ]:
+        src_ds = gdal.GetDriverByName("MEM").Create("", 1, 1, 1, gdal.GDT_UInt16)
+        ct = gdal.ColorTable()
+        ct.SetColorEntry(0, (r, g, b, a))
+        src_ds.GetRasterBand(1).SetRasterColorTable(ct)
+        out_ds = gdal.Translate("", src_ds, format="MEM", rgbExpand="rgb")
+        assert out_ds.GetRasterBand(1).DataType == gdal.GDT_UInt16
+        assert out_ds.GetRasterBand(2).DataType == gdal.GDT_UInt16
+        assert out_ds.GetRasterBand(3).DataType == gdal.GDT_UInt16
+
+    src_ds = gdal.GetDriverByName("MEM").Create("", 1, 1, 1, gdal.GDT_UInt16)
+    ct = gdal.ColorTable()
+    ct.SetColorEntry(0, (255, 255, 255, 255))
+    src_ds.GetRasterBand(1).SetRasterColorTable(ct)
+    out_ds = gdal.Translate("", src_ds, format="MEM", rgbExpand="rgb")
+    assert out_ds.GetRasterBand(1).DataType == gdal.GDT_Byte
+    assert out_ds.GetRasterBand(2).DataType == gdal.GDT_Byte
+    assert out_ds.GetRasterBand(3).DataType == gdal.GDT_Byte