Forgot Password
Pentax Camera Forums Home
 

Reply
Show Printable Version Search this Thread
01-04-2014, 11:35 PM   #1
Site Supporter




Join Date: Oct 2013
Posts: 11
Dead group? of pixels?

I just bought my K5 iis in Oct. Some sunset pictures showed a bright spot in the darkness - as i zoomed in it appeared to be 9 pixels (3x3) were extremely bright. a group of pixels around them were glowing somewhat brighter. I used Pixel Mapping and they disappeared. My question - I see "dead pixels" discussed here - is a 3x3 group of them normal?
Thanks JimmyL

01-04-2014, 11:41 PM   #2
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 43,125
QuoteOriginally posted by JimmyL Quote
I just bought my K5 iis in Oct. Some sunset pictures showed a bright spot in the darkness - as i zoomed in it appeared to be 9 pixels (3x3) were extremely bright. a group of pixels around them were glowing somewhat brighter. I used Pixel Mapping and they disappeared. My question - I see "dead pixels" discussed here - is a 3x3 group of them normal?
Thanks JimmyL
I've seen multiple adjacent hot pixels before, but it's not likely for 9 pixels to die in the same area. Could you post an example developed from a raw file?

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

01-05-2014, 01:35 AM   #3
Site Supporter




Join Date: Oct 2013
Posts: 11
Original Poster
I took the pictures in "best quality" 16mp jpg - then I pixel mapped and it fixed the problem - so I don't have a RAW sample. Is the jpg version not a valid way to evaluate the problem? Is it possible that there were not 9 pixels and the jpg interpreted the data that way?
01-05-2014, 09:05 AM   #4
Site Supporter




Join Date: Oct 2013
Posts: 11
Original Poster
Here's a screen shot:

Attached Images
 
01-05-2014, 09:16 AM   #5
Veteran Member
PPPPPP42's Avatar

Join Date: Jan 2012
Location: Wisconsin
Photos: Albums
Posts: 847
My K20D did that right after I got it used off ebay a long time ago, even in first short exposures so it wasn't an overheat or something. I have heard of large burned spots on other cameras in various forum threads. It was an intermittent huge hot spot that clearly showed up in all the pictures. The pixel mapping darkened the bunch, and now if you pixel peep in just the right area of my pictures you will see what looks like a tiny (actually massive from a pixel count standpoint) faint cigarette burn. Its in every single picture in my album that isn't a scanned film image but good luck finding it in almost all of them even when you know where it is.
It may seem like the end of the world, but its pretty easy to fix in photoshop on the very few pics where it lands in a highly visible spot which is much more rare than you'd think. If its under warranty send it in, it won't get better if your issue is the same as mine though it might be intermittent. Make sure you have a lens cap pic clearly showing the burn spot before you send it in just in case it temporarily goes away. Don't pixel map fix if you are going to send it in.

This is before the pixel map fix (lens cap pic):
https://www.pentaxforums.com/forums/members/46390-pppppp42/albums/4594-pictures/picture68037.jpg

This is after:
https://www.pentaxforums.com/forums/members/46390-pppppp42/albums/4594-pictures/picture68038.jpg

EDIT: mine in after fix pictures in original resolution when pixel peeping shows up as a line of blacked out pixels almost 9 pixels long with a flare around it of blur. Yours is much smaller in the pic you posted so you will likely be just fine with the pixel map fix. Most of the glitch is flare usually and I misunderstood and thought the actual dead spot was 9 pixels not including flare.

Last edited by PPPPPP42; 01-05-2014 at 10:07 AM.
01-05-2014, 09:45 AM   #6
Veteran Member




Join Date: May 2012
Posts: 698
That image represents one hot pixel. It is the de-bayering, noise reduction and jpeg encoding that spread the effect to the adjacent pixels.
01-05-2014, 11:56 AM   #7
Administrator
Site Webmaster
Adam's Avatar

Join Date: Sep 2006
Location: Arizona
Photos: Gallery | Albums
Posts: 43,125
QuoteOriginally posted by lister6520 Quote
That image represents one hot pixel. It is the de-bayering, noise reduction and jpeg encoding that spread the effect to the adjacent pixels.
Exactly!

Adam
PentaxForums.com Webmaster (Site Usage Guide | Site Help | My Photography)



PentaxForums.com's high server and development costs are user-supported. You can help cover those costs by donating. Or, buy your photo gear from our affiliates, Adorama, B&H Photo, or Topaz Labs, and get FREE Marketplace access - click here to see how! Trusted Pentax retailers:

01-05-2014, 11:47 PM   #8
Site Supporter




Join Date: Oct 2013
Posts: 11
Original Poster
As I posted the picture I noticed that it could possibly just be the brightest pixel in the center
with the problem. Thanks for the replies.
JimmyL

Reply

Bookmarks
  • Submit Thread to Facebook Facebook
  • Submit Thread to Twitter Twitter
  • Submit Thread to Digg Digg
Tags - Make this thread easier to find by adding keywords to it!
pentax help, pixels
Thread Tools Search this Thread
Search this Thread:

Advanced Search


Similar Threads
Thread Thread Starter Forum Replies Last Post
Hot/Dead Pixels in Video ChrisTrevino Video and Pentax HDSLRs 8 05-22-2013 04:09 PM
K-7 Hot/Dead pixels TakeshiKovacs Pentax DSLR Discussion 3 09-10-2012 10:12 AM
DEAD Pixels shang Pentax DSLR Discussion 5 09-09-2010 11:12 AM
Dead pixels? Luke_ Pentax DSLR Discussion 8 08-10-2009 08:17 PM
Dead pixels! andrei46 Digital Processing, Software, and Printing 3 08-24-2007 01:01 AM



All times are GMT -7. The time now is 03:16 PM. | See also: NikonForums.com, CanonForums.com part of our network of photo forums!
  • Red (Default)
  • Green
  • Gray
  • Dark
  • Dark Yellow
  • Dark Blue
  • Old Red
  • Old Green
  • Old Gray
  • Dial-Up Style
Hello! It's great to see you back on the forum! Have you considered joining the community?
register
Creating a FREE ACCOUNT takes under a minute, removes ads, and lets you post! [Dismiss]
Top