artifacts maze pattern

[leeonmaui]

Aloha,

Sometimes/rarely images I get from my Pentax 645D and process using Photoshop ACR  have a noticeable "maze pattern."
It is not a common occurrence, and at first I thought it was the result of sharpening, or resizing, but now I am certain it is not, but somehow is in the image itself.

Any help with dealing with this occasional problem would be appreciated.
 

[Bart_van_der_Wolf]

Aloha,

Sometimes/rarely images I get from my Pentax 645D and process using Photoshop ACR  have a noticeable "maze pattern."
It is not a common occurrence, and at first I thought it was the result of sharpening, or resizing, but now I am certain it is not, but somehow is in the image itself.

Any help with dealing with this occasional problem would be appreciated.

Hi,

That's indeed a strange looking (more checkerboard than maze) artifact. Have you tried another Raw converter (to see if it is caused by the Raw converter or by the image data itself)?

In post-processing there may be several ways to repair some of it in Photoshop, but it would be better to avoid it to begin with.

Cheers,
Bart

[deejjjaaaa]

Aloha,

Sometimes/rarely images I get from my Pentax 645D and process using Photoshop ACR  have a noticeable "maze pattern."
It is not a common occurrence, and at first I thought it was the result of sharpening, or resizing, but now I am certain it is not, but somehow is in the image itself.

Any help with dealing with this occasional problem would be appreciated.
 

you can email your raw directly (I mean upload somewhere and send a link) to Eric Chan ( http://people.csail.mit.edu/ericchan/ -> "madmanchan@gmail.com" ) if you indeed sure that it is demosaick artefacts and not your sharpening/NR parameters

[IliasG]

Maze artifacts in 645D raws are due to green channel imbalance (it's around 2% on average)
If you use RawTherapee you can set  "Green Equilibration" slider at a value around 3 to correct this

http://rawtherapee.com/forum/viewtopic.php?f=3&t=5601
http://50.87.144.65/~rt/w/index.php?title=Preprocessing#Green_Equilibration