32
votes
Multiple copies of the same exposure, but randomizing the noise?
To achieve what you're thinking of you would have to know what the noise was.
If you knew what the noise was then you could just remove that to get clean images.
- 9,539
22
votes
Can I use a single RAW file with stacking to reduce noise?
Can I get the same result by coping a raw ( same exposure ) file many times and stacking to reduce noise as I would if I used many separate exposures?
No. If you stack copies of the same image, you'...
- 31.7k
20
votes
Accepted
What is the advantage of carrying a tripod and ND-filters when you could use image stacking instead?
I'd like preface my answer with a note that a tripod is not only useful in conjunction with ND filters — it also improves the results from image stacking as well. By fixing the position of the camera, ...
- 32.3k
19
votes
Multiple copies of the same exposure, but randomizing the noise?
Image stacking works to reduce noise because the noise is random — or at least, ideally so — while the stars are (famously) constant.
That means that (once you've corrected for rotation) the stars ...
- 143k
13
votes
Can I use a single RAW file with stacking to reduce noise?
You cannot. Removing noise via photo stacking works on the principle that the noise in your images is random, and appears in different places of the image between exposures. When you stack multiple ...
- 774
13
votes
What is the advantage of carrying a tripod and ND-filters when you could use image stacking instead?
Well, with regards to your (1)... You could carry a light tripod (or beanbag or any other way of stabilizing a camera) and use only a single ND filter instead of several stacked filters.
With regard ...
- 5,128
9
votes
Multiple copies of the same exposure, but randomizing the noise?
What you're asking about is generally called star-eating. From an algorithm point of view, in an astrophotograph, how can software determine what is signal (that is, stars) vs. what is noise?
A ...
- 32.3k
8
votes
How do I sum images?
Imagemagick cannot be used to compose 30 images in one step. The documentation states:
Image Composition is the process of merging two (and only two) images
in a variety of ways.
The following ...
- 4,553
8
votes
Are there image stacking (astrophotography) options on MacOS that don't involve running a Windows VM?
There are possibly several options available. From a cursory search, native Mac applications include:
Nebulosity
Keith's Image Stacker
PixInsight (cross-platform)
Starry Landscape Stacker
If none of ...
- 32.3k
7
votes
Will stacking more images produce more detail in this galaxy photo?
Stacking more images reduces noise to signal ratio, but don't add resolution or details.
In order to enhance resolution, my advice is to use a prime lense, instead of a zoom one. Even if it has less ...
- 1,251
7
votes
Will stacking more images produce more detail in this galaxy photo?
Yes, but No.
Your question is will it produce more detail, and yes stacking more images will reduce noise which will let you see more detail. And at least as important, you are taking calibration ...
- 101
6
votes
What causes and how can I avoid this moiré pattern in a composite night sky photograph?
Even I had experienced similar problems while shooting night sky photos and later stacking them together although not as apparent of a moire pattern as you have. after a bit of troubleshooting, I ...
6
votes
Possible to do median image merge in Photoshop CS6 (NOT Extended)?
Yes, I have done it in CS5 and CS6 with the following:
File > Scripts > Load Files into Stack
Select all layers and use Edit > Auto Align to align them
Layer > Smart Objects > Convert to Smart Object
...
- 33.3k
6
votes
What is the advantage of carrying a tripod and ND-filters when you could use image stacking instead?
For me the main advantage is... Joy.
I enjoy a lot more taking photos, people places, products, rather than editing the images, especially on automated tasks, like stacking photos. Of course, there ...
- 23.8k
5
votes
How to know the resulting iso of stacked images?
It doesn't really work that way. But even if it did, it would depend on the way you stack the images. Do you add them together? Do you average them? Use some other even more complex method?
Stacking ...
- 175k
5
votes
Multiple copies of the same exposure, but randomizing the noise?
As others have pointed out, what you describe is not possible. If you could randomize the noise, it would mean that you can already detect what is noise and what is not. Then you could just as easily ...
- 151
5
votes
Will stacking more images produce more detail in this galaxy photo?
In my limited experience (back when Astrostack was the hot item, and using video captured at 640x480 with a webcam -- call it 1998 or so), stacking more frames will decrease the appearance of noise by ...
- 7,113
5
votes
Accepted
How to remove satellite streaks from photos?
Sequator should offer a "select best pixels" option that can be used to reduce satellite interference. Otherwise, there is a somewhat helpful article at Sky&Telescope that points to a ...
- 494
4
votes
Stack star photos without trails but WITH sharp foreground?
I agree with Randy's response but believe I have a better solution for case a.
If noise reduction of the sky background is your intent, you can take a few short exposures and stack them in DSS with ...
- 41
4
votes
Accepted
How to Record Videos at Full Resolution with Nikon D750 for Astrophotography?
D750 won't output video at higher resolution unless a hack or firmware update are released
D750 does most probably use line skipping and it seems that even Panasonic GH4 (or other camera with full ...
- 4,770
4
votes
Accepted
Why is my frame stacked image showing a grid?
TL;DR: The edge-discontinuity errors between 8×8 blocks introduced by the DCT compression used in JPEGs is magnified by your image stack, which is why the "grid" is so prominent.
If the frame ...
- 32.3k
4
votes
Possible to do median image merge in Photoshop CS6 (NOT Extended)?
There's a tool called imagej (or its newer equivalent fiji) designed for use on scientific images. It does this out of the box (assuming the images are aligned). You'd probably need to save as .tiff.
...
- 3,772
4
votes
Exposure in Astrophotography
OK - first, the H-alpha issue:
DSLRs incorporate an Infra-red blocking filter, so that the colours come out correctly for normal shots, without being affected by infrared wavelengths.
Unfortunately, ...
- 3,003
3
votes
Possible to do median image merge in Photoshop CS6 (NOT Extended)?
A (better ?) alternative method using Photoshop CS6 exists :
Import your photos using basics script : file -> Scripts -> Load files into Stack
Align : Select all the layers and Edit -> Auto-align ...
- 4,163
3
votes
How do I sum images?
After attempting to apply the repeated composite technique with HDR images and ending up with clamped output, I discovered the ...
- 131
3
votes
How do I sum images?
You can use GIMP.
Open the 1st image.
Open the 2nd image as a layer (Ctrl + Alt + O).
Change layer mode to "Addition" (Dialogue - Layers - Mode).
Open next image as a layer.
Change layer mode to "...
- 1,791
3
votes
Image Stacking for macrophotography
I've not yet graduated to Helicon Focus, though I'm open to persuasion at the moment.
I've found already, just using Photoshop's built-in stacking tools that unless you have a very steady hand & ...
- 23.1k
3
votes
Photoshop stuck at Align Selected Layers Based On Content
For some unknown reason, I've decided to give it a third try after killing Photoshop again, and after a few minutes, it started working:
It's the exact same file on the exact same computer. I only ...
- 396
3
votes
median stack mode is blurring my stars
The Earth rotates, which causes the stars to appear to move, which would be expected to cause them to appear blurry when the images are stacked. Consider using a program, such as ...
- 26.9k
Only top scored, non community-wiki answers of a minimum length are eligible