jespino
commented
1 year ago I've been investigating a bit on this issue, and I want to provide some extra info here:
It looks like related to the Alpha Channel. The webpinfo command gives me the following output:
File: test.webp
RIFF HEADER:
File size: 58606
Chunk VP8X at offset 12, length 18
ICCP: 1
Alpha: 1
EXIF: 0
XMP: 0
Animation: 0
Canvas size 210 x 210
Chunk ICCP at offset 30, length 680
Chunk VP8L at offset 710, length 57896
Width: 210
Height: 210
Alpha: 1
Animation: 0
Format: Lossless (2)
No error detected.This is saying that there are three chunks. The first one is the VP8X, which works fine. The second one, the ICCP (The Color Profile), is not implemented in the decoder, and the third one is a VP8L chunk, and because we already declared that we need Alpha, we will check if the Alpha channel is defined. Because we ignore the ICCP, there is no alpha channel defined.
If you use image magick to convert from that file to png and back to webp, the webpinfo command gives the following info:
File: test2.webp
RIFF HEADER:
File size: 14520
Chunk VP8X at offset 12, length 18
ICCP: 1
Alpha: 1
EXIF: 0
XMP: 0
Animation: 0
Canvas size 210 x 210
Chunk ICCP at offset 30, length 680
Chunk ALPH at offset 710, length 3308
Chunk VP8 at offset 4018, length 10502
Width: 210
Height: 210
Alpha: 0
Animation: 0
Format: Lossy (1)
No error detected.The main difference is the ALPH chunk is there, so it works perfectly now.
From the code perspective, what happens is that the alpha variable is not initialized before the VP8L chunk is processed.
gopherbot
What version of Go are you using (
go version)?Does this issue reproduce with the latest release?
Yes.
What operating system and processor architecture are you using (
go env)?go envOutputWhat did you do?
main.go
```go package main import ( "fmt" "image" "log" "os" _ "golang.org/x/image/webp" ) func main() { reader, err := os.Open(os.Args[1]) if err != nil { log.Fatal(err) } m, _, err := image.Decode(reader) if err != nil { log.Fatal(err) } fmt.Printf("Successfully decoded %s. Image bounds: %s\n", os.Args[1], m.Bounds()) } ```What did you expect to see?
What did you see instead?
Notes
This is not an animated WebP image.
This image is not corrupt:
cwebpexiftoolTest image
test.webp