// the sng command-line tool. Package png doesn't keep that metadata when
// png.Decode returns an image.Image.
var fakegAMAs = map[string]string{
	"ftbbn0g01": "",
	"ftbbn0g02": "gAMA {0.45455}\n",
}

// fakeIHDRUsings maps from filenames to fake IHDR "using" lines for our
// approximation to the sng command-line tool. The PNG model is that
// transparency (in the tRNS chunk) is separate to the color/grayscale/palette