//ProjectGray returns a greyscale sinogram (or radon projection) of img
// N(default: 360): number of image rotation on which a projection will be done
// A naive simplistic approach
// Sinograms looks like this :
// θ1 θ2 θ3...θN
// | | | |
// | | | |
func ProjectGray(src image.Image, N int) (*image.Gray, error) {
if N == 0 {
N = 360
}
step := 180.0 / float64(N)
size := src.Bounds().Size()
overX := int(float64(size.X) * 1.1)
overY := int(float64(size.Y) * 1.1)
var img image.Image = image.NewGray(image.Rect(0, 0, size.X+overX, size.Y+overY))
img = imaging.Overlay(img, src, image.Pt(overX/2, overY/2), 1)
size = img.Bounds().Size()
D := max(size.X, size.Y)
out := image.NewGray(image.Rect(0, 0, N, D))
// for each given angle θ
for n := 0; n < N; n++ {
θ := float64(n) * step
draw := image.NewRGBA(image.Rect(0, 0, img.Bounds().Dy(), img.Bounds().Dx()))
//have a duplicate img rotated by θ
err := graphics.Rotate(draw, img, &graphics.RotateOptions{Angle: manipulator.Rad(θ)})
if err != nil {
return out, err
}
sinogram := make([]float64, size.X)
// get column average profile
for y := 0; y < size.Y; y++ {
for x := 0; x < size.X; x++ {
greyColor, _ := color.GrayModel.Convert(draw.At(x, y)).(color.Gray)
sinogram[x] = sinogram[x] + float64(greyColor.Y)
}
}
//Set out line with sinogram
for d := 0; d < D; d++ {
out.Set(n, d, color.Gray{uint8(sinogram[d] / float64(size.Y))})
}
}
return out, nil
}
func Overlay(images []*ingest.Image) (*ingest.Image, error) {
if len(images) == 0 {
return nil, fmt.Errorf("empty slice was passed in")
} else if len(images) == 1 {
return images[0], nil
}
meta := CommonMeta(images)
path := OverlayName(images)
fi, err := os.Stat(path)
if err != nil && os.IsNotExist(err) {
// ok we will make it below
} else if err != nil {
return nil, err
} else if fi.Size() > 0 {
return &ingest.Image{path, meta}, nil
}
imgs := make([]image.Image, 0, len(images))
for _, i := range images {
img, err := ingest.LoadImage(i.Path)
if err != nil {
return nil, err
}
imgs = append(imgs, img)
}
overlay := imgs[0]
for i := 1; i < len(imgs); i++ {
overlay = imaging.Overlay(overlay, imgs[i], image.Pt(0, 0), .50)
}
err = ingest.WriteJpeg(path, overlay)
if err != nil {
return nil, err
}
return &ingest.Image{path, meta}, nil
}