Free people (re)mover in Photoshop "Extended"

[Experiment_626]

This is long -- but if you have an "extended" version of Photoshop, it may be worth your time to read. There are several of us here who shoot lots of bracketed exposures for HDR and might be able to benefit from this even if we didn't originally shoot with it in mind.

This only works in the "Extended" versions of Photoshop from CS3 forward. The standard version may be able to get you part of the way there, but I cannot say.

If you're like me (and I know I am), you like shots of WDW that are devoid of guests. Makes you kind of feel like you have the place to yourself when you look at such a photo -- and how often does that happen in reality? It can also take a phenomenal amount of patience to get a photo without guests -- or require lots of cloning and healing (or both). But Photoshop Extended can automate removing guests for you ...

Now, this won't work for everything. This will work best with a tripod. As I usually shoot for HDR, I've almost always got the camera on a tripod anyway. To use this tip, just take multiple sets of bracketed exposures -- and many as you stand (as long as the light doesn't change drastically). As long as the people in the frame keep moving, this will work -- although in places where there tends to be a constant stream of people, it may not ...

Once you get home, here's the procedure (in CS3 Extended -- it might differ slightly for newer versions) ... In Photoshop, choose File->Scripts->Load Files into Stack ... Then, choose your exposures in Photoshop. If you shoot sets for HDR, open each matching exposure. In other words, open up your "-2" exposures together, and so on. Also, choose the "Attempt to Automatically Align Source Images" option and the "Create Smart Object after Loading Layers" checkboxes. Then click OK.

Photoshop will chug along for a while -- how long it takes depends on your computer and how many photos you shot. When it finishes, you'll get a new untitled document with a Smart Object layer. Select (but don't open) the Smart Object layer in the Layers palette. Go to the Layer menu (not the palette) and choose Smart Objects -> Image Stack Mode -> Median. Again, Photoshop will go off to sulk and think for a bit.

What Photoshop is doing is comparing all the layers and removing anything that isn't in all (or maybe more than half -- not sure) of the layers, which of course are your original photos. When it is done, you should see the people who moved through your frame have automagically vanished! Of course, in my experience, there will be at least one person who never moved, at least not enough -- or there will be at least one spot that always had someone in it. Still, this trick should help keep cloning to a minimum.

As a free bonus, this trick also helps remove another thing that is randomly different from one frame to the next -- noise. So in some cases, even if there are no guests in a shot, you might want to try this to see if you like the free noise reduction it performs.

As an avid HDR shooter, I had a tendency in the past to shoot a ridiculous number of bracketed sets of images, just for the sake of overkill or maybe because I'm nuts. Regardless, now that I've discovered this trick I'll be going back through some of my old photos to see if I've got some on which this will work. And I guess I'll be going back to shooting multiple bracketed sets again -- my wife will be thrilled at the extra time that takes!

Scott

 

[Experiment_626]

Really? Nothing?

Am I the only person here with access to Photoshop Extended?

I'm going to investigate whether it is possible to do this -- in perhaps a less-automated form -- in the regular versions of Photoshop.

Scott

 

[Marlton Mom]

I have Photoshop CS4 extended so this is something that eventually I'll be able to use. However, at this point my skill set is still miles away when using photoshop and I am plodding along and moving steadily forward.

Thanks for taking the time to lay all this out for all of us on the Dis boards. Your efforts are not wasted!

As soon as I get my new, more powerful computer up and running I plan on extending my HDR skills and efforts so this info is a gold mine for someone like me.

Thanks again,
Marlton Mom

 

[10dedfish]

I think this is great information, and will see if I can replicate this with GIMP. More than likely not, but one can hope.

Matt

 

[Experiment_626]

Thanks, guys!

In my limited evaluation of this technique, it appears to have some advantages (beyond just the automation aspect) over the manual technique of arranging multiple shots into one file as layers, and then using layer masks to hide unwanted elements from one layer to the next. In practice, I had found that to sometimes reveal subtle differences in exposure from one frame to the next, even when the original camera settings were identical. In contrast, this technique seems, perhaps through its work in averaging all the frames together, to present a sort of "ideal" exposure that doesn't display those subtle but telltale signs of masking.

I realized last night there are various ways to adapt this into a workflow. If you're shooting for HDR, you might prefer to use multiple bracketed sets to create multiple HDR images in the software of your choice at the same settings for each, save those as 16-bit TIFF files, and then use this technique on the resulting files. As long as there isn't too much overlapping "ghosting" in your HDR images, it should still work -- and again, it should reduce the noise in your final image to boot.

Also, I may have over-emphasized HDR in my original post. This trick is certainly not limited to HDR -- and with the ability of the software to align images (I presume it uses the same algorithms that the excellent "Photomerge" feature uses to stitch panoramas), it doesn't even mandate use of a tripod. You could certainly fire off a series of hand-held exposures at a normal setting, and use this same trick to remove "intruders."

I just think it is exceptionally useful for HDR shooters, as the many exposures we need mean we're typically shooting in one place for a longer period of time than those who are shooting single-shot exposures -- increasing the odds that we're going to have unwanted people crossing through the frame. Waiting for those people to exit can add lots of time to our shooting -- and who can predict whether someone else won't appear before he first person is out of the frame? I know that happens to me a lot. The waiting can be interminable. Armed with this, I can simply shoot more sets of exposures and not worry about people moving through the frame -- as long as they do keep moving. I think that will result in a net savings of time.

Scott

 

[gruZ]

Hey Scott,

Not sure if this is exactly what you were doing, but here is a video of this type of PP with CS3:

http://www.frederickvan.com/photoshop-tutorial-removing-crowds

Thanks for reminding me about this - I had this bookmarked for some time but had forgotten about it!

Thanks,

(another) Scott

 

[Experiment_626]

Hey Scott,

Not sure if this is exactly what you were doing

I haven't had a chance to watch it yet, but it sure sounds like it's the same.

What happened was that I read about the trick somewhere a few years ago and got really excited by it. However, at the time I was using CS2, which apparently can't do this, and it took a while before I could upgrade -- by which time I had forgotten about it ... almost. Recently something (a stray cosmic ray or something; I have no idea) reminded me of it and I decided to try it. I remembered enough about how it was done to poke around and figure it out. The results got me all excited again, and I decided to share it with you guys.

Scott

 

[Code]

I've only tried this once.. my goal was to get a broad daylight shot of Main Street without anyone on it. Unfortunately when I tried, it was just too crowded and there were spots that were never uncovered by the crowd.

I do plan on trying this more on my next solo photo trip

As for using multiple exposures to reduce noise, though, I've done that quite a few times and it works GREAT (though for noise reduction, I use mean stacking mode rather than median). Every time you double the number of shots, you reduce the equivalent ISO by 1 stop. So if you have 1 shot at ISO 1600, 2 shots would be ISO 800 equivalent, 4 = 400, 8 = 200....

Here's a shot that was 4 handheld ISO 800 exposures for an equivalent of ISO 200...

Crossroads by CodyWDWfan, on Flickr

 

[Experiment_626]

I've only tried this once.. my goal was to get a broad daylight shot of Main Street without anyone on it. Unfortunately when I tried, it was just too crowded and there were spots that were never uncovered by the crowd.

I think the more shots you get, the better it seems to work. If you have a given area that has people in it in two shots and no people in one shot, there's going to be some ghosting, or so it appears. How many exposures did you use in the aforementioned attempt?

Scott

 

[Code]

I think the more shots you get, the better it seems to work. If you have a given area that has people in it in two shots and no people in one shot, there's going to be some ghosting, or so it appears. How many exposures did you use in the aforementioned attempt?

Scott

I didn't have much time, I think I tried 15 exposures in rapid fire, it wasn't enough time between shots, nor enough time from first to last for people to get movin'. I have a time lapse timer for next time I try (exposure every X seconds), should make it easier.

Yes definitely the more shots, the better.. 3 is not enough. Remember that median is the "middle value" in a dataset, the value that splits the set evenly. If you only have 3 shots, anywhere that is covered by a person in 2 out of the 3, the person will show up.

For my Main Street shot idea, next time I'll probably try 60 shots over a minute using the time lapse timer.