SpriteExtend and Canon JPEG

The module SpriteExtension 1.36 (14 Nov 2010) fails to disply JPEG files created by some Canon cameras. In this files the DHT (Define Huffman Table) marker follows next the SOI (Start Of Image) marker. This seem not to be the standard maker order. Moving the DHT marker just before the SOS (Start Of Scan) maker makes SpiteExtend happy and the JPEG is shown. It would be fine, SpriteExtend could be more tolerant to the marker order. I can supply a lot of sample JPEGs ;-)

Moving the DHT marker just before the SOS

You sure it’s not SOF you’re looking at? SpriteExtend will (currently) stop when it finds a SOS/SOI/SOF when hunting for a DHT, this differs from more recent versions of the JPEG library which only stop on a SOS/SOI.

No, I’m not sure.

The marker order in this Canon files is

- SOI

- DHT

- DQT

- SOF

- SOS

So moving DHT before SOS is the same as after SOF if this is the point.

I unterstand the JEPG fileformat, not the JPEG library.

I think I see what you’re saying, so the order that makes it work for you is SOI/DQT/SOF/DHT/SOS? Can you post a link to an example EXIF from this camera, or open a fault ticket and attach it.

With this JPEG SpriteExtend fails: Link (3.017 KB!!)

More samples you find here: Link

Thanks for the link, fixed in 1.39.

Excellent! Thank you.