Banding in the sky

Tringa

Tringa

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Dave
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Does anyone have an idea what has caused the banding in the sky on this shot?

It was taken about 1000 GMT this morning with a Pentax K5 and the 18-55mm kit lens set at 18mm at approximately 90 degrees to the sun.

F7.1@1/500s.

ISO 200

No filter on the lens.

The only PP was converting the original DNG file (on which the banding is also evident) to JPEG and resizing.

All other shots taken today that included sky, including a shot virtually straight into the sun, show the same banding.

Thanks

Dave

IGP1870_2.jpg
 
My guess would be the sun light reacting with the lens coating perhaps ?

Les :shrug:
 
I hope this is wrong, but have you recently cleaned your sensor?
 
This looks like 7bit file, or very very compressed JPEG.

What software do you use to process it?

You could always put the DNG on some FTP or skydrive and let us have a look if you don't mind.

I would really go against the suggestion the sensor is dirty or anything like that. It is a digital artifact.
 
it's not banding but posterisation iirc the sensor can't cope with the colours it sees and it's made worse by compression
 
Went out today at about the same time and fortunately the weather conditions were fairly similar.

I took about 20 shots and in none of them was there any sign of the banding.

I'm still puzzled by the cause but I'm relieved it has gone.

Dave
 
copied from another forum

It is caused by not having enough color information to fill in the transition from one subtle shade of true gray to another at ther 8-bit level in which this photo was made or reproduced. This only seems to happen when you are dealing with a color close to true gray (near-identical RGB values) and in subtle transition areas. Because this happens in areas with nearly no color at all - essentially a defacto 4-bit gray scale condition is created - working in a wider color space like Adobe 98 RGB or ProPhoto RGB is not a real answer. This is not about separating hue or colors from one another, but in separating the level of tones (0-255) from one another. Keeping your workflow in 16-bit (after the original upgrade from in-camera 12 capture) helps a lot with this issue, and with almost any color variation from neutral gray, the effect is either non-existent or barely noticeable.

It's just about the software not having enough information from the file to produce the "in-between" tones in 8-bit to properly define the tone ramp so that the tonal transition from darker or lighter tones to their opposites appears as smooth as you see it with your eyes. There are three solutions: work in 16-bit and don't "overstress' your file with drastic changes in processing, add some color to your backgrounds other than neutral grey or, alternatively, try to shove the offending transition area into a darker tonal range and add enough noise and a very mild blur to the offending areas to mask the posterizatrion look.
 
Tringa said:
The only PP was converting the original DNG file (on which the banding is also evident) to JPEG and resizing.
Click to expand...

It looks like posterisation caused by compression to me but it's strange that the original camera RAW (DNG) file showed the same effect - that seems to rule out the conversion to a lower bit-depth JPEG being the cause.

Does the K5 have different compression & bit-depth options for its RAW files (DNG and/or PEF format)? e.g. Nikons have these options for RAW (NEF) files:

  1. Uncompressed (12-bit or 14-bit)
  2. Compressed (12-bit or 14-bit)
  3. Lossless compressed (12-bit or 14-bit)
 
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