"corduroy" artifact?

[nartreb]

Look at the dark trees at upper left in this photo:

It's as if a corrugated texture had been mapped over the photo. I just noticed it in another shot as well: same camera, a different snowy day, visible over dark background, affects only upper part of the photo. Each time, only visible in one photo out of the batch.

Any idea what's causing this?

 

[kmorgan]

I did an internet search "vertical lines in digital photo" and got a post my the (in)famous David Metsky on another forum:

http://www.dcresource.com/forums/showthread.php?t=33154

Bottom line, bad sensor...

 

[David Metsky]

It could indeed be a sensor going bad. What make and model?

 

[nartreb]

Canon A620. It's my go-to camera when I can't accommodate the weight or bulk of my SLR, but I guess it's starting to get long in the tooth (bought it in December 2005).

 

[David Metsky]

There was a recall on the CCD in many Canon models (they used a Sony CCD that was flawed) but they fixed the problem before the A620 so you're not covered there. It could simply be a JPG artifact but the vertical lines means that it probably isn't. My guess is that it will either slowly get worse or someday just fail completely.

3 years out of a digital camera is pretty good in my opinion. There are lots of great cameras on the market today.

 

[MichaelJ]

How visible is it on the original 3072x2304 image?

 

[nartreb]

Overall about the same - I use "cubic mode" for size reduction and it's quite faithful to the original. Of course if you zoom in at full size, the lines are about twice as wide. I haven't tried using a noise filter yet, I bet I could at least soften the lines a lot at full size and soften them further by using a cruder method of size reduction.

 

[MichaelJ]

Some great examples of digital photo problems and explanations here. I'm still thinking about what you're seeing ...