Need image stacking software (long exposures)

[david_r._edan]

<p>Here's a page that explains what I'm talking about.<br>

http://www.tawbaware.com/imgstack.htm<br>

<br />Basically, if ,for example, the correct/desired exposure of the scene is 2 minutes, one can capture 4 separate images, each exposed at 30 seconds and have them 'stacked' to achieve the desired exposure.<br>

I have zero experience with this and I want to explore this technique.<br>

The "Image Stacker" (link above) is dated, plus it doesn't work (I get some crazy error on my PC).<br>

There are at least several alternatives and I thought I'd ask what's best for what I want to do as I don't like installing random stuff on my system.<br>

For example, there's the DeepSkyStacker. It looks impressive and I think it's free but I'm not sure if it's good for processing low-light cityscapes.<br>

I'm looking for something that can input and output 16-bit tiffs. I don't mind if the software costs money as long as I can properly evaluate it.<br>

<br />If anyone wants to share their insights on this topic in general, that'd be great!</p>

[John Crowe]

<p>I like using Photoshop CS6. I have just begun using layer stacking for focus stacking but I am sure it works for exposure stacking as well.</p>

[hjoseph7]

<p>I think Helicon Focus has a stacking function.</p>

[ellis_vener_photography]

I use Photoshop CC2014.

[alan_cox3]

<p>I'm using PhotoAcute, for 2x resolution improvement, as well as noise reduction. However, I'm not sure of it's current support and sales status. </p>

[david_r._edan]

<p>I have PhotoAcute and I sometimes use it to slightly increase the sharpness of my images. I don't see how it can be used to stack exposures.<br /> I'm not sure that we're on the same page here. I address to all the kind gentlemen who contributed to this discussion thus far.<br /> I want to learn and master the technique of stacking the <strong>exposure</strong>, not focus and not anything else.<br />It's a similar technique they use to photograph nebulae through the telescope and landscapes lit only by the moonlight (that look like they've been taken during the afternoon). I want to try this technique for something entirely different and that is why I am not sure that software aimed at astrophotography is what I need.<br /> I'm not 100% certain how this technique can obtain detail in areas where there is none but I assure you that it takes more than a little tweaking in Photoshop.<br /> I am not talking about shooting star trails where you can just capture a nice set of pictures, stack them on top of each other in CS6 and apply the "Lighten" blending mode.<br /> I wouldn't use CS6 even for star trails. As you may or may not be aware, there will be slight misregistration between each and every image in the stack, even under the most sterile conditions. In a real-world scenario theses misregistrations will be more than negligible. They can be caused by: camera's mirror+shutter+diaphragm rattling the whole setup with EACH exposure. They can be caused by the elements such as the wind and seismic vibrations. Bear in mind that I'm not talking about camera shake but rather the fact that for ALL of the images the camera will be in a slightly different position. When you begin merging those frames in Photoshop, the sharpness of the composite image will degrade with EACH additional frame.</p>

<p>I need a dedicated software that can ALIGN all the frames prior to merging them. By "align" I mean: shift left or right, up or down and rotate, on <strong>sub-pixel</strong> level. And by 'merging' I mean increasing the effective exposure of the composite, i.e. adding detail to the final image that is not present in any single frame in the stack because all of those frames are effectively <strong>underexposed</strong>.</p>

<p>I'll rephrase that. I want to take a bunch of grossly <strong>underexposed </strong>pictures and combine all of them to get 1 good, properly exposed picture.<br>

<br />DeepSkyStacker (http://deepskystacker.free.fr), supposedly can do that but it's aimed at astrophotography. Astrophotography is not what I'm about. There are all kinds of software out there, so I thought I'd ask what's best for what I need to do.<br /> What I need to do is demonstrated on this page: http://www.tawbaware.com/imgstack.htm<br /> <br /> Any input is welcome.</p>

[tom_mann1]

If you are not familiar with "HDR photography", you should read through a few of the many articles on the subject.

Although the details of the method are slightly different from the method u suggest, the end result sounds exactly like

what u are looking for.

 

Tom M

[david_r._edan]

<p>I am familiar with HDR photography, probably more so than most people who utilize it, as I've been perfecting it for years. I even put my own twist on it (actually a few of those). To take it even further I want to see if synthesizing exposures works for what I have in mind.<br /> What I've been talking about all along is <strong>not</strong> HDR.<br /> Here is a gallery. Underneath each picture there is a description of the technique that was used. Short version: this ain't HDR.<br /> http://www.tawbaware.com/maxlyons/cgi-bin/image.pl?showFileName=ST_PICT4183_4187_Stacked_Rosslyn.jpg&gallery=8&pwd=</p>

[Mark Z]

<p>David, I have wondered about the same problem. It's similar to working with film, and sandwiching two or more negatives in an enlarger (the densities getting added, not averaged). The analogous digital method has applications in astronomy, as you have probably seen. I know that Registax and Images Plus are used (among others) for astrophotography. Registax may have file size limitations, but I don't know for sure what they are. Astrophotography is very demanding on getting the layers to line up exactly, so the software that is used will likely be adaptable to what you need.<br>

<br />From my very limited experience with such software, it is not entirely intuitive and the learning curve seemed steep to me. There may be online tutorials, or you may be able to connect with someone who could walk you through the basics.<br>

<br />In Photoshop, you ought to be able to add the values in layers in a similar way. Apparently, there is a summation mode that might be what you need. http://www.dummies.com/how-to/content/use-smart-object-stack-modes-in-photoshop-cc.html<br>

Perfectly aligning the separate shots would still be an issue, however.<br>

<br />Good luck in your pursuits.</p>

[thormod]

<p>I'm confused David. Correct exposure 2 min. 4 ea. 30 sec. stacked will give correct exposure?<br /> I thought that if you stacked 4 ea. 30 sec. images, you would get a single image with 30 sec exposure.<br /> If you had said 1 30 sec, 1 one min, 1 90 sec, and one 2 min, I'd think Bracketing and HDR .If you have a shallow depth of field, I would understand stacking 4 images with the same exposure, but with different focus..<br /> Tom.<br /> Eager to learn unknown stuff.<br>

Edit:<br>

Sorry David. Just found your link to ImageStacker. Wow!<br>

This I godda learn:)</p>

<p> </p><div></div>

[tom_mann1]

A question, David ... Looking though some of your sample images, it appears as if the dynamic range of the image is

reduced by stacking. For example, in the shot of the Lincoln Memorial, the bright lights do not have the bright halos

around them that I would have expected if I shot a single longer exposure sufficient to brighten the trees to the level in

your photo. If my observation is correct, and you are using the "add" mode, I don't see how this can possibly decrease

the dynamic range. The same goes for the "brighten" mode unless the image is flickering from exposure to exposure.

 

Can you speak to this a bit?

 

Thanks,

 

Tom M

[q.g._de_bakker]

A stupid question perhaps, but, David, why not just expose longer?<br>Stacking cannot add detail that is not present in the single frames. You can only stack what's there.<br>The result is that low light values are summed to create a higher light value. Extending the exposure does the same - without having to align pixels - without having to touch the camera to create a series of underexposed images, and without having to do any work in PS or other programs.

[david_r._edan]

<p>Tom: The photos you are referring to were not taken by me but rather by the gentleman who's selling the software.</p>

<p>Q.G.: "Why not just expose longer?" How long can you go with a DSLR? I have a Nikon D800 and I wouldn't expose for anything longer than a couple of minutes. The artifacts are bad enough at 30 seconds (and I do know how to turn on the Long Exposure NR).<br>

Here's a link for you and everyone else:<br>

https://photographylife.com/astrophotography-tutorial<br>

Skip to the 'General Procedure' and read the first paragraph. Pay attention to the last sentence.<br>

I've been wanting to investigate this technique for many years. Couldn't get around to it because it wasn't high on the list.<br>

It's been out there for many years. Obviously, us, regular folk, do not synthesize exposures. Someone out there does. There are pictures.<br>

I realize now that I must refer to a forum dedicated to Astrophotography and take it from there.</p>

<p>Thanks to everyone who tried to help.</p>

[gooseberry]

<p>Have never used them, but have a look at <a href="http://www.astrosurf.com/buil/us/iris/iris.htm">IRIS</a> and/or <a href="http://www.astronomie.be/Registax/">RegiStax</a>; they <em>may</em> do what you're after.<br>

Good luck!<br>

<br />P.S.<br />Here's a <a href="http://www.russsscope.net/staxtutorial.htm" rel="nofollow" target="_blank">tutorial</a> for the latter.</p>

[david_r._edan]

<p>Thanks!</p>