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06-08-2014, 06:09 AM   #1
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K-30: Striations and pixelated blotches in sky pics

I don't know why my K-30 is doing this...When I take photos of varying gradients of solid colors there appears to be blotchy rendering, sometimes bands of pixelated areas. Any ideas on why it is doing this and what I can do to alleviate the problem?
Thanks!








Last edited by dcpropilot; 06-08-2014 at 06:23 AM.
06-08-2014, 06:29 AM   #2
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Your EXIF on all three photos shows 100,100. I don't know if that's something your software is doing but the K-30 ISO doesn't go that high. That's kind of strange.
06-08-2014, 07:38 AM   #3
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maybe you want to try a reset or a fw upgrade.might resolve the issue
06-08-2014, 07:59 AM   #4
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This sort of issue has been reported frequently and invariably it's a problem created by the software that's been used to process the images.

Presumably the images straight out of camera don't show this?

06-08-2014, 08:09 AM   #5
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What RAW converter are you using? We had several threads a few months back with similar problems and the cause was traced to work flow and the RAW convertor.


Steve
06-08-2014, 08:39 AM   #6
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I agree, but additionally I would recommend using Tiff as output from the raw converter and avoiding jpeg.


I any use jpeg for distribution but for anything else I use Tiff, in this case as an experiment see what a Tiff looks like and I sure you will discover its the jpeg engine that's at fault and therefore your workflow.
06-08-2014, 09:23 AM   #7
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This could easily be caused by jpeg compression, so I second the recommendation that you check the results in a different format.

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06-08-2014, 10:19 AM   #8
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Yeah, that looks like JPEG compression and data reduction. Try increasing your JPG quality to the max or use TIFF. All of that will disappear but get ready for larger file sizes.

06-08-2014, 11:49 AM   #9
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Don't worry. There's nothing wrong with your camera or your computer, or your software. It's called posterization and it is one of the disadvantages of digital photography. There is a good explanation of it in Digital photography for Dummies; I passed my copy along to a friend so I may mangle the explanation a bit (not being the most technically literate).

The gist of it is that digital sensors computer software and screens have limits to the number of actual colors that they are able to capture, process and represent. When confronted with a large area of subtle gradations some of the tones can't be represented and banding results.
That is where the concept of bit depth comes in (which I will certainly mangle so I suggest that you look it up). Essentially with higher bit depth more subtler gradations of tone are possible. Photoshop Elements processes images at a bit depth of 8bits/channel. Photoshop is capable of 16 and even 32 bits but I believe most monitors are only capable of displaying at 16 bits. (I've heard of 32 and even 64 bit screens). The sensor on your K 30 is 12 bits; the sensors on the K5 and K3 are 14.

For most purposes 8 bits works OK, but one has to be careful of pushing the tones in processing. The banding becomes most apparent by pushing up the saturation too far.

The more technically literate on this site, I'm sure, can clarify and correct any faults in this explanation.

PS. As mentioned by others above jpg compression is also be a factor. As data is lost tonal gradations also become diminished.
I and I'm sure most of us have confronted this issue at some time or other. It's part of the art of post processing. Cheers

Last edited by sundr; 06-08-2014 at 12:41 PM.
06-08-2014, 12:44 PM   #10
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Most modern monitors show 16.7m colors (24bit)
Example of common monitors are the Dell UltraSharp and the Samsung range.
Even the cheapest AOC 'Office' monitors show 16.7m colours.
The best way to test your editing output is a 'wet test' - IOW: Print them.
06-08-2014, 01:16 PM   #11
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QuoteOriginally posted by Steve.Ledger Quote
Most modern monitors show 16.7m colors (24bit)
Example of common monitors are the Dell UltraSharp and the Samsung range.
Even the cheapest AOC 'Office' monitors show 16.7m colours.
The best way to test your editing output is a 'wet test' - IOW: Print them.
Thanks for the correction. I just took a look at my computer info and found that my 2008 MacBook has a 32 bit LCD. Better than I thought.
06-08-2014, 01:59 PM - 1 Like   #12
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Good reading;
http://www.cambridgeincolour.com/tutorials/bit-depth.htm
Image Posterization

Last edited by Oldbayrunner; 06-08-2014 at 02:05 PM.
06-08-2014, 02:38 PM   #13
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For some reason, the dng photos on the screen on the camera show the bands also. I was using faststone to convert to jpg; but I think it may be resolved using picasa 3. I don't know how...

Below are dngs processed/converted to jpg via picasa 3:


Last edited by dcpropilot; 06-08-2014 at 05:56 PM.
06-08-2014, 04:50 PM   #14
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I haven't experienced this in Faststone when viewing then pressing 'A' to load the actual raw data rather than the embedded JPG.
06-08-2014, 05:58 PM   #15
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I'll have to mess around with the settings, and press A (for raw) in faststone to maybe get better results.. Now, I have to figure out to get rid of hot pixels I am seeing in the finished image...
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