From 0d9bf2757e71e64938b02c397d1d6e5666c5a213 Mon Sep 17 00:00:00 2001
From: Nigel Tao <nigeltao@golang.org>
Date: Wed, 6 Mar 2013 10:08:46 +1100
Subject: [PATCH] image/jpeg: for progressive JPEGs, the first SOS segment
 doesn't necessarily contain all components.

Fixes #4975.

R=r, minux.ma, bradfitz
CC=golang-dev
https://golang.org/cl/7469043
---
 src/pkg/image/jpeg/scan.go | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)

diff --git a/src/pkg/image/jpeg/scan.go b/src/pkg/image/jpeg/scan.go
index e3ae8ae441c..a69ed17489c 100644
--- a/src/pkg/image/jpeg/scan.go
+++ b/src/pkg/image/jpeg/scan.go
@@ -109,9 +109,11 @@ func (d *decoder) processSOS(n int) error {
 	myy := (d.height + 8*v0 - 1) / (8 * v0)
 	if d.img1 == nil && d.img3 == nil {
 		d.makeImg(h0, v0, mxx, myy)
-		if d.progressive {
-			for i := 0; i < nComp; i++ {
-				compIndex := scan[i].compIndex
+	}
+	if d.progressive {
+		for i := 0; i < nComp; i++ {
+			compIndex := scan[i].compIndex
+			if d.progCoeffs[compIndex] == nil {
 				d.progCoeffs[compIndex] = make([]block, mxx*myy*d.comp[compIndex].h*d.comp[compIndex].v)
 			}
 		}