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12-21-2008, 06:30 PM   #16
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QuoteOriginally posted by Sharkonwheels Quote
Using the Pentax Photolab, and PEF raw images, TOOL>AutoFix doesn't fix it.
Slight and strong both failed, and actually actually, depending on the contrast against
the surrounding area, makes it worse. It decreased the actual SIZE of the image defect, but uses a brighter color pinkish replacement on the pixels

Only way I've been able to get rid of the defect, is zoom to 4:1 or 8:1 in Lightroom, and
use the heal tool manually. It's a bit much to have to do that to EVERY image...

On the samples above, they happen to be about an 8x8 grid or so. The size varies depending on the contrast,
but the defect is never smaller than about a 7x7 or 8x8 section.

I HAVE used the Dust alert, and it found nothing.
I also tried using pixel mapping, and same results.

One thing I DID notice, is tripping the shutter with the lens cap on, or taking a picture of a VERY black item (audio speaker)
showed no defects. Does that happen to give any more clues?

T
8x8 is a jpg pixel block. Most likely you have one or 2 hot red pixels. Software compression and demosaicing is pushing it to a larger size.
JPG Image Artifacts
Shoot a dark frame in RAW. Convert to TIFF and download pixel scanning software
StarZen Technologies, Inc; DataFlex tools and books

12-21-2008, 06:35 PM   #17
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When I view the raw versions (PEF - both Pentax PhotoLab and Lightroom, and DNG in Lightroom) it's still roughly the same size.I just showed you the jpg version, but it's the same on the RAW version. Between 7x7 and 9x9 depending ont the colors and contrast between the colors.

I will do the test now, and report the results.

Hmmm....wonder if I'm doing something wrong?
Set the mode to 'M' and then as the instructions say, do a 1/30, 1sec, 2sec, 3sec, 4sec shutter speed snaps.
Tried as DNG, and exporting from lightroom, the pixeltest app scans in like 3 seconds. Nothing in the preview,
histogram shows nothing, and no dead/hot pixels.

Is it possible the test is running on 14M+ pixels in 3 seconds?

export is TIFF, 16 bit, sRGB colorspace

Also tried using PEF, exporting in Pentax PhotoLab to Tiff, 16bit, basically same exact result. 3 seconds to scan
a 14MP picture seems a bit fast to me!

T

Last edited by Sharkonwheels; 12-21-2008 at 07:25 PM.
12-21-2008, 07:38 PM   #18
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QuoteOriginally posted by Sharkonwheels Quote
When I view the raw versions (PEF - both Pentax PhotoLab and Lightroom, and DNG in Lightroom) it's still roughly the same size.I just showed you the jpg version, but it's the same on the RAW version. Between 7x7 and 9x9 depending ont the colors and contrast between the colors.

I will do the test now, and report the results.

Hmmm....wonder if I'm doing something wrong?
Set the mode to 'M' and then as the instructions say, do a 1/30, 1sec, 2sec, 3sec, 4sec shutter speed snaps.
Tried as DNG, and exporting from lightroom, the pixeltest app scans in like 3 seconds. Nothing in the preview,
histogram shows nothing, and no dead/hot pixels.

Is it possible the test is running on 14M+ pixels in 3 seconds?

export is TIFF, 16 bit, sRGB colorspace

Also tried using PEF, exporting in Pentax PhotoLab to Tiff, 16bit, basically same exact result. 3 seconds to scan
a 14MP picture seems a bit fast to me!

T
Default threashold of 60 is too high... drop it down.
At 20 I get 2 HP. 10 seems about right. Look for clustered coordinates. Yes scan is very fast.
12-21-2008, 07:54 PM   #19
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I get nothing until i go down to threshold of 5, and then 2 HP show up.

OK - let's assume the sensor is 100% correct...what else could cause this?
As I said earlier, when I took a snap with lens cap on, I saw nothing, and when I took a snap of one of my rear surround speakers (black) I got nothing.

Mebbe something on the mirror?
The lens look clean to me...

Please also DO keep in mind I'm a n00b, especially when it comes to DSLR's

T

12-21-2008, 08:15 PM   #20
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QuoteOriginally posted by Sharkonwheels Quote
I get nothing until i go down to threshold of 5, and then 2 HP show up.

OK - let's assume the sensor is 100% correct...what else could cause this?
As I said earlier, when I took a snap with lens cap on, I saw nothing, and when I took a snap of one of my rear surround speakers (black) I got nothing.

Mebbe something on the mirror?
The lens look clean to me...

Please also DO keep in mind I'm a n00b, especially when it comes to DSLR's

T
Threshold 5 is nothing. and as I said, sometimes these things are dynamic.
Some show up sometimes (as in increasing exposures ect..)
Anyway a visual idea of what you are looking at/for...
That 40 listed is a bright blue hot pixel.
I can't really explain what you are seeing (it is a hot pixel cluster) only that it's annoying but not earth shattering. My usual recommendation is to get it replaced if it's in an annoying spot (personal judgement).
You need to shoot a dark frame at the speed that you are seeing that pixel cluster. Keep in mind too slow of shutter and the camera will do a "dark frame subtraction" eliminating most of the hot pixels..
Processing an image and pulling up the shadows or just a general increase in exposure can change your "5" to a 50 making it much more visible. To verify any of this just import your photo into an editor w/ rulers and get an idea of exactly where the pixel is. Match it to your coordinates in the test. I would bet it will match one.
At 5 I have 43 "hot pixels" at 2/10sec.

Last edited by jeffkrol; 12-21-2008 at 08:49 PM.
12-21-2008, 08:43 PM   #21
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As I noticed yesterday, though, when I take lens-cap-on, or really dark pictures, nothing bad shows.
However, as in the samples I attached above, light backgrounds and objects (sky, white floor tiles, my dog's white fur) and semi-dark backgrounds and objects ( forest green towel, for example) shows the "spot."

I received the K20D Friday, and it has either had the lens on, with lens cap, or the body cap when lens was not on, which has been rare. I have not left it lying around without the lens cap on, either.

Also, this "spot" has been on every shot matching the above conditions, from the get-go.

Just wondering if there could be something else besides the sensor, like maybe something on the lens that my eyes can't see, as it is obviously VERY small. And, when it's there, according to the above conditions, it is in the same location.

T
12-21-2008, 09:02 PM   #22
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Here's another example so you can see how pronounced it can be on light backgrounds.
Here, it sticks out like a sore thumb! Conditions as above - light (white) background.

yeah, yeah, I know, I just didn't know how to use the red-eye reduction yet...

T
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12-21-2008, 09:11 PM   #23
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It's hot pixel. Just shoot RAW and let the RAW converters take care of them.

12-21-2008, 09:29 PM   #24
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How would I do that in Pentax Photo Lab?
I shoot using RAW PEF, and the way I tried, was to open the PEF in the Pentax Photo Lab.
I do Tools->Autofix and neither the 'slight' or 'strong' options fix it.
They both make it a slight bit smaller, but much brighter than original, which in the end, actually makes it worse!

T
12-21-2008, 09:45 PM   #25
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Not sure about the Pentax sw, but both Adobe ACR & LR work great on removing hot pixels automatically.
12-21-2008, 09:54 PM   #26
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Maybe it's getting a bit OT, but how do you do it automatically in LR?
If it is OT, a pm would be most appreciated.

T
12-21-2008, 10:00 PM   #27
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When you open the RAW files, LR will just detect any hot pixels and remove them w/o any user intervention.
12-21-2008, 10:05 PM   #28
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This LR or LR2?
I have LR2, and when I open a DNG from the library, it doesn't do anything automatically.

T
12-22-2008, 08:44 AM   #29
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QuoteOriginally posted by Sharkonwheels Quote
This LR or LR2?
I have LR2, and when I open a DNG from the library, it doesn't do anything automatically.
Sure it does - like any RAW processor, it has to convert the image from its original RAW state to RGB so you can see it. In so doing, it is not only perfoming Bayer demosaicing, but also applying some sort of preprocessing exposure curves and white balance / color interpretation. That's quite a bit of work it does automatically.

Now, whether the hot pixel removal is part of this process I can't say for LR2 I can't say.
12-22-2008, 01:49 PM   #30
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Hmmm....maybe I need to do some mods on the presets or something...
When I go into the library module, and select an image, it just shows it in the middle portion, WITH the defect.

Now I know I can use the dus spot remover (cure and heal modes), but that is manual (right now)
I read in the manuals how to use sync to carry over the spot in batch imports, so I probably just need to do more RTFM

In the meantime, thought I'd chime in, that I contacted Adorama about it, and I did explain to them that I was trying to research the info, so as to not do an unnecessary RMA with them, and they basically said they woudl swap it out.

They have been MORE than accomodating, so I didn't want to just RMA something back, knowing it might be that I'm a n00b, which would not be fair. Kudos to them (and Helen) in a major league way.

I'll keep futzing around with this thing - otherwise, this is a FANTASTIC piece of kit!

T
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