ImagePixelExtractorTransform support for images with no alpha channel (#1821)

Author: yaeldMS

src/Microsoft.ML.ImageAnalytics/ImagePixelExtractorTransform.cs

@@ -483,7 +483,9 @@ private ValueGetter<VBuffer<TValue>> GetGetterCore<TValue>(Row input, int iinfo,
                             return;
                         }
 
-                        Host.Check(src.PixelFormat == System.Drawing.Imaging.PixelFormat.Format32bppArgb);
+                        Host.Check(src.PixelFormat == System.Drawing.Imaging.PixelFormat.Format32bppArgb
+                            || src.PixelFormat == System.Drawing.Imaging.PixelFormat.Format24bppRgb,
+                            "Transform only supports pixel formats Format24bppRgb and Format32bppArgb");
                         Host.Check(src.Height == height && src.Width == width);
 
                         var editor = VBufferEditor.Create(ref dst, size);
@@ -542,28 +544,6 @@ private ValueGetter<VBuffer<TValue>> GetGetterCore<TValue>(Row input, int iinfo,
                         else
                         {
                             int idstMin = 0;
-                            if (ex.Alpha)
-                            {
-                                // The image only has rgb but we need to supply alpha as well, so fake it up,
-                                // assuming that it is 0xFF.
-                                if (!vf.IsEmpty)
-                                {
-                                    Single v = (0xFF - offset) * scale;
-                                    for (int i = 0; i < cpix; i++)
-                                        vf[i] = v;
-                                }
-                                else
-                                {
-                                    for (int i = 0; i < cpix; i++)
-                                        vb[i] = 0xFF;
-                                }
-                                idstMin = cpix;
-
-                                // We've preprocessed alpha, avoid it in the
-                                // scan operation below.
-                                a = false;
-                            }
-
                             for (int y = 0; y < h; ++y)
                             {
                                 int idstBase = idstMin + y * w;

src/Microsoft.ML.ImageAnalytics/ImageResizerTransform.cs

@@ -411,7 +411,7 @@ protected override Delegate MakeGetter(Row input, int iinfo, Func<int, bool> act
                             destWidth = (int)(sourceWidth * aspect);
                             destHeight = (int)(sourceHeight * aspect);
                         }
-                        dst = new Bitmap(info.Width, info.Height);
+                        dst = new Bitmap(info.Width, info.Height, src.PixelFormat);
                         var srcRectangle = new Rectangle(sourceX, sourceY, sourceWidth, sourceHeight);
                         var destRectangle = new Rectangle(destX, destY, destWidth, destHeight);
                         using (var g = Graphics.FromImage(dst))

test/Microsoft.ML.OnnxTransformTest/DnnImageFeaturizerTest.cs

@@ -134,7 +134,7 @@ public void OnnxStatic()
                     Assert.Equal(512, buffer.Length);
                     numRows += 1;
                 }
-                Assert.Equal(3, numRows);
+                Assert.Equal(4, numRows);
             }
         }
 

test/Microsoft.ML.OnnxTransformTest/OnnxTransformTests.cs

@@ -210,7 +210,7 @@ public void OnnxStatic()
                     Assert.Equal(1000, buffer.Length);
                     numRows += 1;
                 }
-                Assert.Equal(3, numRows);
+                Assert.Equal(4, numRows);
             }
         }
 

test/Microsoft.ML.Tests/Scenarios/TensorflowTests.cs

@@ -56,17 +56,17 @@ public void TensorFlowTransforCifarEndToEndTest()
             {
                 ImagePath = GetDataPath("images/banana.jpg")
             });
-            Assert.Equal(1, prediction.PredictedScores[0], 2);
-            Assert.Equal(0, prediction.PredictedScores[1], 2);
+            Assert.Equal(0, prediction.PredictedScores[0], 2);
+            Assert.Equal(1, prediction.PredictedScores[1], 2);
             Assert.Equal(0, prediction.PredictedScores[2], 2);
 
             prediction = predictFunction.Predict(new CifarData()
             {
                 ImagePath = GetDataPath("images/hotdog.jpg")
             });
             Assert.Equal(0, prediction.PredictedScores[0], 2);
-            Assert.Equal(1, prediction.PredictedScores[1], 2);
-            Assert.Equal(0, prediction.PredictedScores[2], 2);
+            Assert.Equal(0, prediction.PredictedScores[1], 2);
+            Assert.Equal(1, prediction.PredictedScores[2], 2);
         }
     }
 

test/Microsoft.ML.Tests/ScenariosWithDirectInstantiation/TensorflowTests.cs

@@ -654,7 +654,7 @@ public void TensorFlowTransformCifar()
                     Assert.Equal(10, buffer.Length);
                     numRows += 1;
                 }
-                Assert.Equal(3, numRows);
+                Assert.Equal(4, numRows);
             }
         }
 
@@ -718,7 +718,7 @@ public void TensorFlowTransformCifarSavedModel()
                     Assert.Equal(10, buffer.Length);
                     numRows += 1;
                 }
-                Assert.Equal(3, numRows);
+                Assert.Equal(4, numRows);
             }
         }
 

test/Microsoft.ML.Tests/TensorFlowEstimatorTests.cs

@@ -175,7 +175,7 @@ public void TestTensorFlowStatic()
                     Assert.Equal(10, buffer.Length);
                     numRows += 1;
                 }
-                Assert.Equal(3, numRows);
+                Assert.Equal(4, numRows);
             }
         }
 
@@ -222,7 +222,7 @@ public void TestTensorFlowStaticWithSchema()
                     Assert.Equal(10, buffer.Length);
                     numRows += 1;
                 }
-                Assert.Equal(3, numRows);
+                Assert.Equal(4, numRows);
             }
         }
 

test/data/images/images.tsv

@@ -1,3 +1,4 @@
+tomato.bmp	tomato
 banana.jpg	banana
 hotdog.jpg	hotdog
 tomato.jpg	tomato