Archive for the ‘After Dark’ Category

Image Blending in Lightroom with Enfuse

The Minneapolis skyline after dark can be spectacular.   In the picture above the skyline and its vibrant colors are reflected on the mirror-like finish of Lake Calhoun.

Dynamic Range

Before we can start a discussion about HDR (High Dynamic Range), we first need to begin with an understanding of what dynamic range means.  In photography dynamic range is the ratio between the minimum (shadows) and the maximum (highlights) light intensities in an image.   This ratio is measured in f-stops when referring to digital cameras.

I will leave it to the experts to debate how f-stops of dynamic range the various formats and cameras can attain.  Even if you use the very best DSLR it is still likely that you will on occasion (often?) find photo opportunities that will exceed the dynamic range of the camera.  This is where HDR and/or blending techniques come in.

For those looking for more information about dynamic range you can find a great reference here.

HDR or High Dynamic Range

HDR has become a very popular technique due in large part to a number of very good tools that have become available.  Photomatix is probably the most well known and popular, and while it does a good job, it can be very difficult to get decent results.  Most HDR that I have seen ends up looking kind of unreal and/or like a cartoon.   Some people like this, but it is not for me.

The trick, I think, is to use the tools to accomplish a subtle effect and to not go overboard.  While the goal is to present a much larger dynamic range than can be accomplished with a single shot, you should also strive for realism.

While Photomatix and similar tools use tone mapping and exposure fusion, there is another technique that can be used which is image blending.    One of the tools that can be used for blending is Enfuse.

Enfuse

Enfuse is an open source tool which can be downloaded for free.  The Wiki page does a much better job of describing it:

Enfuse Wiki page

Enfuse is a command-line program used to merge different exposures of the same scene to produce an image that looks very much like a tone mapped image (without the halos) but requires no creation of an HDR image. Therefore it is much simpler to use and allows the creation of very large multiple exposure panoramas.

Sounds like just what we want.  🙂

Lightroom plug-in

The downside to Enfuse is that it can be daunting to use for those less technically inclined.  It is a command line tool, and if you’ve never ventured out of Windows and into the world of command prompts, it could be a show stopper.   However, if you have Lightroom there is an alternative.

Timothy Armes, who has authored a number of Lightroom plug-ins, has created one just for Enfuse called LR/Enfuse. In short this plug-in allows you to simply select the images that you would like to blend within Lightroom.

Accessing the plug-in

Once you have the images selected the next step is to start the plug-in.   The Enfuse plug-in is a bit different from most, to launch the Enfuse process select  File->Plug-In Extra’s->Blend Exposures using LR/Enfuse.

Configuration

When the plug-in is launched you are presented a window that contains four tabs that configure and control the output.  It may seem like a lot but  the settings for the most part do not change all that much between sessions and the actual blending options are limited to one tab (Enfuse)

Output tab

The output tab is where you specify the name and location of the output file.  I almost always output to the 16 bit TIFF format.  You can also opt to import the output file back into Lightroom, copy meta data to the blended image, etc..  You can see my typical settings below.

Auto Align Tab

The auto-align configuration determines how (or if) the images should be aligned during the blend.  Even shooting on a tripod I find that I do need to have the plug-in automatically align the images.  Even the slightest shift of the source material can lead to a blurry image, auto-aligning can correct for that.

Enfuse Tab

This tab is the one place where you are able to tweak the blending.   I leave the levels set to automatic and if you are just starting out you should too.

The other parameters control the weighting factors used by Enfuse to blend the images.  Input images are weighted according to their exposure, contrast and saturation.  Changing these values will effect the blend and how the pixels are blended.  The contrast weighting is the only one of the values that is not determined on a per pixel basis.    Instead it looks at a window of values whose size is determined by the Contrast Window Size.

Al the bottom of all the panels is a generate previews button,  I would recommend that you leave the auto generate unchecked and instead manually create a preview when you are done with  you r changes.

 

Configuration Tab

The configuration tab typically needs to be set up only once.  The only config here that is interesting is the preview pixel size.   The larger the size the longer it takes to generate the preview.  The default is 500 which is too small for my taste, 800 seems about right.

Shooting to blend

When shooting HDR, you typically will need 3-5 images which are bracketed at equal stops.    The beauty of blending is that you can be much more liberal with your source material.    The documentation for Enfuse recommends starting out with pictures bracketed by 2/3 to 1 1/3 stops to make it easier to visualize.   Typically you want to get a “base” exposure that is as close to the look you like and bracket from there.  If you are concerned about the shadows, bracket up and don’t worry about bracketing on the –EV side for highlights.  Blending is very forgiving and is not dependent on a certain mix of photos.

Also, to make your life easier, you will want to use a tripod.  Some of the various blending and/or tone mapping products will handle slight movements of the camera, but from my experience it is just best to start with images that are framed as identically as possible.

For the image I present here I shot three exposures.   As I said earlier I am not a huge fan of the really overdone HDR in most cases.  For some source material it works pretty well (see my article on Topaz adjust for one that I think puts the effect to good use.  IMHO   :-))   but for this scene I definitely wanted something with more realism.  Blending is just the tool.

 

Exposures

Below are the three images that were blended to create the photo at the beginning of this article.   As you can see each image captures detail in some areas but not in all.  By blending the three images, we are able to get a final result that combines the areas from each photo to ultimately deliver an image that exceeds the dynamic range of a single frame.

Exposure at –2 EV

In this image you can see the details in the city lights and in the reflections on the water.   The buildings themselves are obscured by the shadows and the tree line is nothing more than a silhouette.

 

Exposure at 0 EV

At this exposure you can see the buildings are opening up and there is detail appearing in the tree line.

 

Exposure at +2 EV

Now we see lots of detail in the tree line but the buildings are washed out.  The city lights are mostly white blobs.

Summary

 

 

Blending images is a great way to increase the dynamic range of your photo.    It also has the advantage of providing a more realistic look, and with less work than the popular tone mapping tools.    As a bonus Enfuse itself is free and the plug-in for Lightroom is much cheaper than the popular tone mapping tools (think PhotoMatix).

In short if you are a landscape photographer, you owe it to yourself to try out Enfuse and blending;   Heck, any photographer would benefit from having this tool in their arsenal.   Download Enfuse and the plug-in and try it out.  I would love to hear from you and see your results.  I think you will be as excited about blending as I am.  🙂

Night Life

This past weekend I made a trip to Duluth for a chance to try out a brand spanking new 5D Mark II.   I arrived as scheduled on Saturday afternoon, unfortunately the 5D didn’t show up until much later.   The weather was not cooperating either.

But, this was not supposed to be about what was not working but rather what did.  After the sun had set for the evening I went down to the harbor hoping for a mix of fog and lights and a great picture…….  Well OK, I went down there because Grandma’s has great food.

Approaching the area I saw that the fog and lights really made for an interesting image.  I got out my camera and tripod and took a few pics.

 

The results

Lift Bridge

© 2009 Gary Udstrand

 

The rain had turned to a slight drizzle and the lights combined with the fog made the exposure level challenging.   I set my camera up on a tripod and chose an aperture of f/7.1 to get a decent amount of DOF while keeping the exposure levels at an acceptable level.   The camera was on a tripod, but the wind and rain were increasing so I wanted to keep the shutter somewhere in the 2-3 second range.  ISO 320 put me in the correct range and would also keep the noise at an acceptable level.

A quick glance at the LCD (chimping!) and I could see that the highlights were overexposed.  I dialed in a –1 EV and reshot.  This time the highlights looked good and the histogram, while bunched up to the left hand side, was as expected.   Overall I am very happy with the shot.

 

Lonely Pier

© 2009 Gary Udstrand

The pier was virtually vacant, myself the only exception, and the deteriorating weather was making me question my decision to stay.    I liked the look of the empty pier and decided to set up for another shot.  Starting with the same settings as the bridge I took the photo and reviewed the histogram.   Since the pier had much less ambient light it caused the highlights to blow even though I was already dialed at a –1 EV.   I increased the EV to a –2 and was able to control the highlights a bit better while still retaining some detail in the shadows.  I liked the balance between the lights and the cold hard concrete, and since the weather was not getting any better I moved along.

 

The Technique

 

Night Shooting

I am a huge fan of shooting after the sun goes down, and the shots above are only a couple of many I shot that night.   Too often when the sun goes down photographers pack away their gear which is unfortunate.  Nighttime offers many opportunities for some very unique and wonderful images.  It does take a bit of twiddling sometimes to get everything right, but the results can be well worth it.

When I shoot at night I like to carry a small LCD flashlight to see the camera and settings.  If you do this make sure you get one that has not only white light but red light as well.  The red will not affect your night vision as much and will allow you to go back and forth between the camera settings and visualizing your composition.

 

Focus

One thing that can be difficult when shooting at night is to get the focus right.  To get the focus right I can offer you a couple of techniques.

  1. Try to find a light, or an object that will provide enough contrast to focus that is at the same distance as the subject.   Once you have focus, turn off the auto focus (if you haven’t already) and turn your camera towards your subject and shoot away.
  2. You should always carry a small flashlight when shooting at night.  Not only can it light the way for you back and forth to your subject, but you can also use it to assist with focusing.  If your subject is close enough simply illuminate it with the torch and focus your camera.  Again, once you have focus you can simply turn off the auto focus and shoot away.
  3. If you are shooting a subject that is at infinity, and your lens has a distance scale (surprising how many nowadays lack this useful feature) you can calculate the hyperfocal distance (the subject of a future blog post!  ;-)) and set your focus via the distance scale on the lens.

In all cases you probably will want to set your camera/lens to manual focus once you have it set.  Also, remember to check it regularly to make sure you have not bumped the focus ring.

 

Bracketing

When shooting at night getting the exposure correct can be difficult.  To ensure you get the results you want it is useful to bracket your shots.   Most cameras nowadays have AEB (Auto Exposure Bracketing) that can make it as simple as firing off three shots.

    For myself I prefer to use the EV adjustment on the camera.  If you are familiar with your histogram and camera display you can usually tell where your exposure is.   If you need more exposure, dial it up a stop or two.   Alternatively if you need less dial out a stop or two.  Knowing and understanding how and when to use EV will improve your photography overall and not just your images taken at night.

    Aperture Priority

    I prefer to use aperture priority for a lot of my shooting, night shooting included.  I would recommend that you start there or use your cameras manual settings.    While you can shoot at night using the program or auto modes I would not recommend it.  Most often the camera will set the lens to its widest setting and start from there.  Largely, that is not what you want.The sweet spot of most lenses is at a couple stops closed down from the maximum aperture.  There is a reason for the old adage “F8 and be there”.   Start with f/8 and change it as conditions and experience dictate.   The tighter apertures will let the lens perform at its best and will also minimize blooming and fuzziness around brightly lit areas (like lightning).

    In closing

    The next time the sun sets keep your camera out.  Set up the tripod and fire away.  One thing is almost certain, you will have the scenery to yourself..  that is unless I am in the area.  🙂

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