First implementation

vendor/gocv.io/x/gocv/dnn_ext.go

@@ -0,0 +1,67 @@
+package gocv
+
+import (
+	"image"
+)
+
+// FP16BlobFromImage is an extended helper function to convert an Image to a half-float blob, as used by
+// the Movidius Neural Compute Stick.
+func FP16BlobFromImage(img Mat, scaleFactor float32, size image.Point, mean float32,
+	swapRB bool, crop bool) []byte {
+
+	// resizes image so it maintains aspect ratio
+	width := float32(img.Cols())
+	height := float32(img.Rows())
+
+	square := NewMatWithSize(size.Y, size.X, img.Type())
+	defer square.Close()
+
+	maxDim := height
+	var scale float32 = 1.0
+	if width > height {
+		maxDim = width
+		scale = float32(size.X) / float32(maxDim)
+	}
+	if width < height {
+		scale = float32(size.Y) / float32(maxDim)
+	}
+
+	var roi image.Rectangle
+	if width >= height {
+		roi.Min.X = 0
+		roi.Min.Y = int(float32(size.Y)-height*scale) / 2
+		roi.Max.X = size.X
+		roi.Max.Y = int(height * scale)
+	} else {
+		roi.Min.X = int(float32(size.X)-width*scale) / 2
+		roi.Min.Y = 0
+		roi.Max.X = int(width * scale)
+		roi.Max.Y = size.Y
+	}
+
+	Resize(img, &square, roi.Max, 0, 0, InterpolationDefault)
+
+	if swapRB {
+		CvtColor(square, &square, ColorBGRToRGB)
+	}
+
+	fp32Image := NewMat()
+	defer fp32Image.Close()
+
+	square.ConvertTo(&fp32Image, MatTypeCV32F)
+
+	if mean != 0 {
+		// subtract mean
+		fp32Image.SubtractFloat(mean)
+	}
+
+	if scaleFactor != 1.0 {
+		// multiply by scale factor
+		fp32Image.MultiplyFloat(scaleFactor)
+	}
+
+	fp16Blob := fp32Image.ConvertFp16()
+	defer fp16Blob.Close()
+
+	return fp16Blob.ToBytes()
+}