robocar-steering/vendor/gocv.io/x/gocv/dnn_ext.go

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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()
}