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Forum: Pentax K-1 10-17-2018, 12:31 PM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
I didn't. It doesn't look like the usual stuck pixels. I'll give it a test on the off-chance.
Rawtherapee's hot-pixel function in the demosaic section seems to do a good job of removing stuck pixels too
Forum: Pentax K-1 10-16-2018, 07:51 AM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
I can thoroughly recommend Rawtherapee for RAW processing. It has an incredible number of options, and for me an intuitive layout, though no doubt it may seem different to other tools. Development is very active (I believe it was one of the first tools to offer pixel shift support).
I have tried the impulse noise reduction tool to remove the white dots and it does seem to do a tremendous job, increasing the threshold slider just to the point where almost all dots are removed.
I've not seen the black dots(yet) that Gimbal mentions above: I guess no tool is going to be perfect, but for the money it's definitely worth it - a no brainer on Linux
Forum: Pentax K-1 10-15-2018, 03:02 AM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
Thank you for that, it saved me the task
The upshot seems to be we have to live with it. Like I stated earlier: Rawtherapee's 'Impulse Noise reduction' does an excellent job of cleaning images up, and coupled with batch processing should make preparation for stacking straightforward. It strikes me that this may be mostly fixable in firmware given how anomolous these pixels are though.

Using Rawtherapee to look at the bayer pattern it looks like (on this image at least) that only green and red pixels are reading high
Forum: Pentax K-1 10-14-2018, 06:00 AM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
- guilty as accused. Only evidence being no-one on here seems to have mentioned it in relation to the K-1ii

ISTR it's somewhere in the long thread about the white dot issue in relation to the K1. I'll check when I get back
Forum: Pentax K-1 10-14-2018, 04:41 AM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
It was taken with a k35mm at f4 I think. There was a fair amount of atmospheric haze too: I was experimenting rather than looking for a great shot. I do realise I was rather pushing the limits at 10 mins, but wanted to explore those limits.
I've perhaps not read widely enough on the subject, but understood that Nikon had some sort of fix for the d810, I was assuming Pentax had done similar.
Forum: Pentax K-1 10-14-2018, 02:53 AM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
I was hoping to avoid LENR because of the additional exposure time, but I understand it is an option for some shots
I process using Rawtherapee, and the impulse noise reduction feature seems to do an excellent job of removing these artifacts. What bothers me is I'm seeing them in the first place. I've not seen similar on the K3 or K30, and thought that perhaps the problem had been fixed on the K-1ii
Forum: Pentax K-1 10-14-2018, 01:59 AM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
I understand about stacking to average out noise, however these white dots are extreme outliers and I don't think normal noise. From what I recall I also tried in camera multiple exposure averaging when I first got the camera and still saw dots. I'd have to look back to check
Forum: Pentax K-1 10-14-2018, 12:45 AM  
K-1ii white dot issue ?
Posted By damianc
Replies: 18
Views: 1,438
Being this far north and with constantly cloudy skies I've not had much opportunity to get out and do some night time photography, however I did get an opportunity a couple of nights ago. Looking at an image taken at ISO 2500 for 600 seconds I see hundreds/thousands of bright dots. Reading the forums I have only seen K-1 owners mention the white dot issue and wondered whether any other K-1ii owners are seeing similar. I've attached a 100% crop of a minimally processed image as an example. The dots don't always appear to be single pixels and are not all white, but are distinctively different from the expected noise.
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