pub fn from_blue_channel<C>(image: &Image<Luma<C>>) -> Image<Rgb<C>>
where
    Rgb<C>: Pixel<Subpixel = C>,
    C: Primitive,
{
    map_pixels(image, |p| Rgb([C::zero(), C::zero(), p.0[0]]))
}
Creates an RGB image by embedding a grayscale image in its blue channel.

# Examples
```
# extern crate image;
# #[macro_use]
# extern crate imageproc;
# fn main() {
use image::Luma;
use imageproc::map::from_blue_channel;

let image = gray_image!(
1, 2;
3, 4);

let expected = rgb_image!(
[0, 0, 1], [0, 0, 2];
[0, 0, 3], [0, 0, 4]);

let actual = from_blue_channel(&image);
assert_pixels_eq!(actual, expected);
# }
```
src/map.rs