image/gif: "invalid pixel value" on image that works in Chrome

[gopherbot]

by KaneZhangAQ:

Source photo url: http://needkane.qiniudn.com/ret6.gif
But go can't get the gif info .

gifConf, err1 := gif.DecodeAll(imgSource)//if imagesource is the gif
        
        println(err1.Error())//result is gif: invalid pixel value

According to the go source code,I find

if len(m.Palette) < 256 {//get 128
            for _, pixel := range m.Pix {
//pixel is 128 too,but my gif is ok,you can see it from the url
                if int(pixel) >= len(m.Palette) {
                        return errBadPixel
                }
            }
    }

[bradfitz]

Comment 1:

Owner changed to @nigeltao.

Status changed to Accepted.

[nigeltao]

Comment 2:

The GIF spec at http://www.w3.org/Graphics/GIF/spec-gif89a.txt says that "Each index
must be within the range of the size of the active color table". The ret6.gif image
linked to is not a valid GIF image, according to the spec, even if whatever image
library Chrome uses accepts it.
I'm closing this bug as Working As Intended, unless somebody presents some evidence that
at least two different widely-used GIF decoding implementations agree on what to do with
this out-of-spec image.

Status changed to WorkingAsIntended.