image/jpeg: avoid documentation argument over whether it's luma

subsampling or chroma subsampling.

Fixes #5569.

R=r
CC=golang-dev
https://golang.org/cl/9900044

diff --git a/src/pkg/image/jpeg/reader.go b/src/pkg/image/jpeg/reader.go
index 862d8dc1b2115af1b172b1e4852101b40909f8eb..356d56220a7596b3bf5b9068e06b39ced4639795 100644 (file)
--- a/src/pkg/image/jpeg/reader.go
+++ b/src/pkg/image/jpeg/reader.go
@@ -174,10 +174,10 @@ func (d *decoder) processSOF(n int) error {
                // values for the Cr and Cb components must be (1, 1).
                if i == 0 {
                        if hv != 0x11 && hv != 0x21 && hv != 0x22 && hv != 0x12 {
-                               return UnsupportedError("luma downsample ratio")
+                               return UnsupportedError("luma/chroma downsample ratio")
                        }
                } else if hv != 0x11 {
-                       return UnsupportedError("chroma downsample ratio")
+                       return UnsupportedError("luma/chroma downsample ratio")
                }
        }
        return nil