image/color.NYCbCrA.RGBA(): possible loss of information (Go 1.6)

[pierrre]

image/color.YCbCr.RGBA() uses a custom code for the conversion YCbCr to RGB, and doesn't use YCbCrToRGB().
The comment in the method says:

    // This code is a copy of the YCbCrToRGB function above, except that it
    // returns values in the range [0, 0xffff] instead of [0, 0xff]. There is a
    // subtle difference between doing this and having YCbCr satisfy the Color
    // interface by first converting to an RGBA. The latter loses some
    // information by going to and from 8 bits per channel.

Go 1.6 adds a new image|color type: NYCbCrA.
But image/color.NYCbCrA.RGBA() calls YCbCrToRGB().
YCbCrToRGB() returns 8 bits per channel, I think there is a loss of information here.

[gopherbot]

CL https://golang.org/cl/18115 mentions this issue.

[pierrre]

@nigeltao thank you! 😀