image/jpeg: support for CMYK images

[gopherbot]

by samuel.stauffer:

To reproduce:

1. Decode CMYK jpeg (attached)

What is the expected output?

A successfully decoded image. Works in Preview.app and ImageMagick.

What do you see instead?

Error "unsupported JPEG feature: SOF has wrong length"

Which version are you using?  (run 'go version')

go version devel +a5efcd1675eb Thu Dec 06 09:47:12 2012 -0800

Please provide any additional information below.

I'm seeing this error for all CMYK jpegs I've tried.

Attachments:

1. err1.jpeg (902176 bytes)

[rsc]

Comment 1:

Labels changed: added priority-later, removed priority-triage.

Owner changed to @nigeltao.

Status changed to Accepted.

[nigeltao]

Comment 2:

Out of curiousity, what program generated these CMYK JPEGs?

[gopherbot]

Comment 3 by samuel.stauffer:

Not sure what created this particular image, but I imagine software like Adobe
Illustrator and other apps meant for printed design would produce CMYK.  This image
comes from a user's avatar on a service I run. It's using Go for the dynamic resizing
proxy to serve the avatar images.

[rsc]

Comment 4:

Labels changed: added size-l.

[gopherbot]

Comment 5 by jsummers3456:

Since the Go library treats YCbCr as a full-fledged color format (rather than as an
internal part of a compression algorithm for RGB images), for consistency the example
image above should probably be called "YCCK", not "CMYK".
Raw CMYK and raw RGB JPEG images do exist. They are rare, but are widely supported by
viewers. If YCCK support is being considered, I suggest that CMYK and RGB be considered
as well.
RGB JPEGs can be created with the -rgb option of the cjpeg utility included with libjpeg
8d.

[nigeltao]

Comment 6:

I'm wary of adding new color types so close to an API freeze. I'm marking this bug as
out of scope for the Go 1.1 timeframe.

Labels changed: removed go1.1, size-l.

[gopherbot]

Comment 7 by kaaloo:

I am also interested in using Go for thumbnailing but have hit this issue with some of
the problem images we have received in the past.

[rsc]

Comment 8:

Labels changed: added go1.2maybe.

[rsc]

Comment 9:

Labels changed: added feature.

[robpike]

Comment 10:

Won't happen for 1.2.

Labels changed: added go1.3maybe, removed go1.2maybe.

[robpike]

Comment 11:

Labels changed: removed go1.3maybe.

[gopherbot]

Comment 12 by dan.pupius:

Here's another example image that causes this error.   Would love to see more extensive
image decoding support. We're using Go to resize and crop user-provided images.

Attachments:

1. 0-sVYLjSP1-47U__fC.jpeg (271255 bytes)

[gopherbot]

Comment 13 by dolby0:

Another sample image, that fails to convert with "unsupported JPEG feature: SOF has
wrong length" error

Attachments:

1. porsche-cayman-2013-3_0.jpg (1053952 bytes)

[gopherbot]

Comment 14 by dolby0:

I think google converted image above, so this is the original
https://www.dropbox.com/s/2kjzt903pup7t2y/porsche-cayman-2013-3_0.jpg

[gopherbot]

Comment 15 by alexander.lobunets:

Yet another example of getting: 
... value jpeg.UnsupportedError = "bad Pq value" ("unsupported JPEG feature: bad Pq
value")

Attachments:

1. bad.jpg (535175 bytes)