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Sharpness
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Thu Mar 05, 2020 7:56 am    Post subject: Artifacts Reply with quote

Sirs:

As you may be able to see, I am making progress on sharpness. I have been finding artifacts when I process the stacks. Some of them are from dust on the sensor. I cleaned it before I shot this stack so I think we can write off that problem in the accompanying image. The artifacts are circled in red. I am wondering if they are hot pixels on the sensor. I must say I doubt that is true. They occur in different colors. I have suspected inadequate light. In this image I am using a Canon 40D and a Pentax 200mm lens with a Mitutoyo_M_Plan-Apo_20x_0.42 objective. I have added more light to my fotodiox portable studio led440, namely a Clar24B light. I have raised the iso to 320 and I'm getting a shutter speed of 1/20 sec. Of course my 40D can't use it's through the lens metering because the lens does not talk to the camera. The ec for this stack was 0. I don't think I find as many of these artifacts when I use the Nikon_plan_10X/0.25_∞/-_WD_10.5. I think I need less light when using it. I can create successful images at iso 200 and without the Clar 24B added light.

Regards,
Larry

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Scarodactyl



Joined: 14 Apr 2018
Posts: 329

PostPosted: Thu Mar 05, 2020 8:14 am    Post subject: Reply with quote

Is the extra green color from you highlighting it?

Those are either dust (on sensor or somewhere on the intervening glass) or hot pixels, probably both. Hot pixels are easy to distinguish since they are individual pixels (and lighter) vs little blurry dark patches. I don't know about other packages but Helicon lets you make a dust map to help reduce the appearance of these lines in a stack, but that likely won't help with hot pixels.
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Thu Mar 05, 2020 10:52 am    Post subject: Artifacts Reply with quote

Sirs:

The dots on the stack are individual spots. I'm attaching a closeup. Also, I'm going to clean lenses. We'll see what shows up or doesn't.

Regards,
Larry

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rjlittlefield
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Joined: 01 Aug 2006
Posts: 20649
Location: Richland, Washington State, USA

PostPosted: Thu Mar 05, 2020 11:11 am    Post subject: Reply with quote

The bright individual dots do look like hot pixels. Helicon's dust mask should be able to deal with those after you get it set up correctly. At https://forum.heliconsoft.com/viewtopic.php?t=95 , Dan Kozub (Helicon's author) suggests shooting a gray frame so that Helicon Focus can identify both dust and hot pixels.

The broad fuzzy green cast surrounding the hot pixels is an effect that I do not recognize. Does that appear in the individual frames, or only in the stacked composite?

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Mon Mar 09, 2020 12:51 pm    Post subject: Color Haze and Hot Pixels Reply with quote

Dear rjlittlefield and Scarodactyl:

I had not realized that you could not see enough detail to see the “hot Pixels.” They turned into haze of different colors. The colors are green, gray and pink.

There seems to be a cubic color haze over bright points. I was going to ask about that next.

I’ve had a cessation of work in the studio and will have to get back on it, maybe tomorrow.

I just don’t like the idea of hot pixels and I am totally puzzled about the “cubic color haze.” I may try other cameras and some different lenses. I have two objective lenses, one a Nikon 10X, the other a Mitutoyo 20X. I’m suspecting the Mitutoyo, which I bought used for the hot pixels issue. They both show the color haze cube around bright spots.

I’ll get back with you as soon and things settle down again. Thanks so much for your helpful comments and observations.

Regards,

Larry
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Tue Mar 10, 2020 9:59 am    Post subject: Stack Artifacts Reply with quote

Dear rjlittlefield and Scarodactyl:
I just had a moment to shoot this series. I shot it with the same camera body and the same lens setup, Pentax 200mm with Mitutoyo 20x mounted.
As Bill Paxton in "Twister" said, “I’m not back.”
I will try to upload a full resolution image if your website will accept it. You can take it to 100% and see what we are talking about. Also notice the repetitions of shapes of artifacts which are not necessarily the same color. Also note the color haze over the high lights.

I'm really stuck.

Regards,
Larry

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rjlittlefield
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Joined: 01 Aug 2006
Posts: 20649
Location: Richland, Washington State, USA

PostPosted: Tue Mar 10, 2020 10:25 am    Post subject: Re: Stack Artifacts Reply with quote

Larry45 wrote:
I will try to upload a full resolution image if your website will accept it.

Photomacrography.net will not store images larger than 1024 pixels image size and 300 KB file length. However, it will accept and automatically downsize images that exceed the 1024 pixels limitation. The downsizing occurs without notification, so it can cause unexpected results if you don't know about the possibility.

If you need to make available a large file, and don't have any other method, then I suggest to open a free account at DropBox.com and upload it there.

Quote:
Also notice the repetitions of shapes of artifacts which are not necessarily the same color.

Repeating shapes are typical of hot pixels, dust spots, and any other defects that occupy the same spot in each source image.

What happens is that the subject appears to move around as the stack is shot, then the stacking software realigns images to keep the subject in one place, and that causes the spots to move around. Each spot looks like detail to be preserved, so the final stacked image can end up showing each dot in all of the many positions that it ever occupied after alignment. The repetition of shapes is because it's common that movement of the source images is dominated by X and Y shifts, which then apply to all of the dots in the same way. Another common pattern is a sort of "starburst" effect caused by corrections to Scale as the stack is processed.

To me the puzzling aspect remains the surrounding haze. I'm the fellow who handles support requests for Zerene Stacker so I see a lot of defect trails, and I cannot recall ever seeing broadly spread color like this surrounding hot pixels.

So I am curious to know, does a broad colored region appear around each bright spot in your source images, or does it appear only in the stacked composite?

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Tue Mar 10, 2020 10:44 am    Post subject: artifacts Reply with quote

Rick,
The broad color region appears around the bright spots in each image of the stack.
Can you do “one drive?” I’ll have to remember how to do it. I think I send you some info so you can get it.
Larry
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Tue Mar 10, 2020 11:05 am    Post subject: Reply with quote

Quote:
broad color region appears around the bright spots in each image of the stack.

OK, then next question: are the source images coming straight from camera, as say JPEG or TIFF, or are they shot as raw and then run through some converter (which one?), or are they being shot raw and fed directly into Helicon Focus which then shows the broad colored region? Or some other workflow, which I haven't thought of?

Quote:
Can you do “one drive?” I’ll have to remember how to do it. I think I send you some info so you can get it.

Once in a while somebody sends me images through OneDrive and I'm able to access them. I have no idea how it works on the sender's end.

--Rik
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Scarodactyl



Joined: 14 Apr 2018
Posts: 329

PostPosted: Tue Mar 10, 2020 1:06 pm    Post subject: Re: artifacts Reply with quote

Larry45 wrote:
Rick,
The broad color region appears around the bright spots in each image of the stack.

That's really weird. I've never seen it before (which means nothing) but if RJL hasn't then it's definitely odd. I wonder if there's some atypical damage to your sensor. Been photographing any laser shows with it?
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rjlittlefield
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Joined: 01 Aug 2006
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Location: Richland, Washington State, USA

PostPosted: Tue Mar 10, 2020 8:53 pm    Post subject: Reply with quote

Larry sent me a full resolution output image. The broad colored regions appear to be comprised of a bunch of 48-pixel squares that track the bright dots. At this moment I'm suspecting image compression gone awry. I'll know more after I see some source images.

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Wed Mar 11, 2020 7:59 am    Post subject: Stack Artifacts Reply with quote

Sirs:

I shoot with my 40D in raw. I run it through Adobe Bridge. This is the third 40D which has done that. For that reason I don't think it is the camera body. I'll shoot you a series with the other 40D I have currently to see if the problem recurs.

Regards,
Larry
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rjlittlefield
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Joined: 01 Aug 2006
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PostPosted: Wed Mar 11, 2020 8:17 am    Post subject: Reply with quote

When you run your raw files through Adobe Bridge, what format do you produce for output? TIFF? JPEG? DNG? If JPEG, what compression level?

If you'd like to send me a source image that shows the problem, and the raw file that produced that source image, I'd be happy to take a look at them.

I expect that would be both simpler and a lot more informative than shooting another body and seeing the same problem.

--Rik
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Larry45



Joined: 16 Jan 2019
Posts: 21

PostPosted: Wed Mar 11, 2020 1:00 pm    Post subject: stack artifacts Reply with quote

Sirs:

I just processed a stack with the other 40D. The results were the same except that the artifacts were located differently.

Regards,
Larry

PS I'll probably shoot a series with the 7D next.
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JKT



Joined: 28 Oct 2011
Posts: 126
Location: Finland

PostPosted: Thu Mar 12, 2020 5:41 am    Post subject: Reply with quote

Try saving the files as tiff from Adobe ... if you don't already.
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