Sunday, January 26, 2014

Digital Workflow 2 - White Balance

This is a continuation of my Digital Workflow series. In my previous post, I talked about camera settings and the importance of shooting RAW images.  In this article, we will discuss the importance of white balance and my approach to setting the WB after the image is captured.  My general workflow for processing IR images is shown below.

  1.       Set up the camera
  2.       Shoot RAW files
  3.       Set White Balance (Nikon Capture NX2 or Nikon View NX2)
  4.       Auto Levels
  5.       Save as TIFF (Do not skip this step!!)
  6.       Noise Reduction
  7.       Black and White processing and/or Channel swap (Photoshop or CNX2)
White Balance
White Balance (WB) is a much misunderstood process with IR photographers. In visible light photography, WB settings are used to remove unrealistic color casts so that objects which appear white in person are rendered white in your photo. In IR photography, WB is used to transform the invisible IR spectrum to a visible spectrum that we can perceive and manipulate. This transformed spectrum is important for color IR post-processing and strangely enough, for black and white post-processing too.


Out of Camera Shot - Daylight WB
Lets take a look at an image captured with an infrared-converted D90. This camera has a standard 720nm infrared filter installed by LifePixel. The image on the left was captured using the camera's daylight WB setting. The histogram shows that this WB setting has assigned some of the IR spectrum to the green and blue channels even though these colors are blocked by the IR filter. That's OK.

We also notice that the red channel is jammed up against the right axis. The image shows some red channel overload and detail clipping. The resulting image is flat and lacks detail.  


Daylight WB with -3EV.
One obvious way to overcome the red channel overload is to decrease the exposure and bring the red channel histogram back to a more centered position. This helps with the whites but we lose details in the shadows (information in the green and blue channels).  

If you have a camera that can accept a custom white balance, you can correct the overload problem by setting a new white balance. Unfortunately, most Nikon cameras will not accept a proper white balance after IR conversion. 


LifePixel White Balance
In my routine photography with a converted Nikon Camera, I use the custom white balance set by LifePixel during the conversion process.  


This approach gives me a good starting point in most situations. The color histograms are fairly well centered and the luminescence histogram (white color on the graph) is to the left of center.  

In my previous post, I mentioned that I do not use the RGB histogram in the camera because the LifePixel WB gives me a good starting point and I am capturing the images as NEF (RAW) files that have all the information the sensor sees. You can also see why I use the luminescence histogram. For my shooting style, a good exposure has the luminescence histogram situated on the left side of the graph but not banging into the axis.  


White Balance in CNX-2
I use Nikon Capture NX2 to further transform the infrared capture during post-processing. This WB shift gives me good tonal separation, good detail, and an image that I can use for further processing.  

After WB, the histogram is well centered with the luminescence, red, green, and blue channels superimposed on one another. The white balance process has almost completely transformed the infrared spectrum into the viable spectrum. We are using all of the captured data and none of the detail has been clipped. 


After applying Auto Levels in CNX2.
One final step is need to complete the IR transformation.  After setting the WB in CNX2, the histogram is centered but there is a gap between the edges of the histogram and the axes. This means that we are not fully utilizing the visual spectrum.    

The final step in this transformation process is to spread out the spectrum. This can be done in several ways. The easiest is to stay in CNX2 and use the Auto Levels function. From the taskbar at the top, select Adjust > Light > Auto Levels.  You can do the same thing in PhotoShop using a Levels layer mask.  However, you must save the image as a TIFF before bringing it into Photoshop. This is important because PhotoShop, Lightroom and other programs will not see any of the changes you make if you save the file as a NEF. These picture white balance changes and picture controls are recorded in the Camera Settings area of the NEF file and other programs cannot read that information. 

Subsequent post-processing steps use color information to make changes in the image. By transforming the infrared spectrum to a visual spectrum, the software can function efficiently. Black and white conversions also use color information in the conversion process and having a well-rendered color spectrum will allow you to better control the conversion process.

-- -- --

Setting the WB using Nikon Capture NX2
The Nikon Capture NX2 (CNX2) program is a full-featured photo editor that uses all of the RAW image data captured by the camera.  In contrast with other photo editors, CNX2 will apply the Picture Controls you set in the camera. In this way, you will be starting with an image that looks like the one you saw on the back of the camera. If you don't like those control settings, you can change them  within the editor.  

For the photographer using a converted Nikon camera, CNX2 has an advantage over the free View NX2 program because it can set the white balance for any NEF (RAW) image. View NX2 works well when you have an area within the photo that you want to be a neutral gray. 

Finally, Jason O'Dell has a general YouTube video showing how to set the white balance in CNX2 and copy the white balance adjustments to other photos. The main difference I have with Jason's procedure is that I use the Marquee tool to draw a box around the entire image. 

LifePixel also has an excellent video tutorial on their website. To find it, you must follow the link and page down to the entry on "Infrared RAW file white balance issues & solutions" entry.



Nikon CNX2 Screenshot
Here is my procedure..  
Click on the triangle next to the Camera Settings header to open that section of controls.  

Click on the “Set Color Temperature” pull down box and select “Set Gray Point.” 







Nikon CNX2 Screenshot
Click on the Marquee Sample radio button, 

Click the start button and use your cursor to draw a rectangle around the entire image. You should see a lot more color and tonal contrast in the image.

Save the image as a TIFF file. This is important because PhotoShop, Lightroom and other programs will not see any of the changes you make if you save the file as a NEF. These picture control changes are recorded in the Camera Settings area of the NEF file and other programs cannot read that information.

You can forego the TIF-generation step if you prefer to do all your post-processing in CNX2. CNX2 can be used to do the channel swap and BW conversion.


-- -- --


Setting the WB using Nikon View NX2
The View NX2 program can be downloaded free of charge from Nikon. Like Capture NX2 above, VNX2 will apply the Picture Controls you set in the camera, Therefore, the image you see with VNX2 will look the same as the image on the back of the camera. VNX2 has a mini version of the Capture NX2 editor and it can do a pretty good job with the white balance if you have something in the image that should be a neutral gray.  

Capture the image in RAW format.

Nikon View NX2 Screenshot
Open the VNX2 software and highlight the NEF file image.

Click on the EDIT button (third from left on the button bar).

An Adjustments panel will open on the right.  Choose White Balance.

In the pull-down box below the White Balance header, choose “Use Grey Point.”


Nikon View NX2 Screenshot
In the pull-down box just below this one, choose 5x5 average.

Click Start then click on an area you want to be gray. 

Click the Finish button.

Save the image as a TIFF or JPG file.  This is important because Photoshop, Lightroom, and other programs will not see any of the changes you made if you save the file as a NEF. The changes described above are saved in the Camera Settings area of the NEF file and other products cannot read that information.

Thursday, January 23, 2014

Digital Workflow 1 – Camera Settings

I have received some requests to share my digital workflow and IR camera settings.  All of this information will not fit into a single post, so I am breaking it into chunks that are easier to download and digest. My general IR workflow is listed below. In this post, I will share my camera settings and discuss the importance of shooting RAW files.

General IR Workflow
  1.       Set up the camera
  2.       Shoot RAW files
  3.       Set White Balance (Nikon Capture NX2 or Nikon View NX2)
  4.       Auto Levels
  5.       Save as TIFF (Do not skip this step!!)
  6.       Noise Reduction
  7.       Black and White processing and/or Channel swap (Photoshop or CNX2)
 Camera Settings


 ISO:  I use base ISO whenever possible. A 720nm filter will exclude about 90% of the luminosity in most scenes so your sensor is in a low-light situation even when it is bright outside. Keeping the ISO as low as possible is helpful because it will decrease the noise in the image.That said, if you need to raise the ISO to get the shot, raise the ISO.  (Noise reduction programs can clean up some of this in post production.). A noisy photo is better than no photo.

White Balance:  I use the LifePixel preset on all my cameras. Only a few Nikon cameras will reliably accept a custom white balance after IR conversion (see below) so I don’t even try to set one. I adjust the WB in post.The next post will address white balance issues. 

Image Quality:  I shoot RAW images exclusively. This allows me to adjust the white balance in post-processing and gives me a lot of after-the-shot flexibility.

Picture Controls:  I use a modified picture control setting for all of my cameras. I start with the VIVID setting then add contrast (1 block to the right of center) and +6 sharpness (6th block from the left). I save this as a custom setting called Vivid&Sharp. 

You are probably wondering why I care about Picture Controls, especially when shooting RAW.  There are two reasons. First, these settings are applied to the image on the back LCD and a sharp contrasty image makes it easier to evaluate the exposure values and other camera settings. Second, I use Nikon Capture NX2 (CNX2) to adjust the white balance. CNX2 will apply the picture controls to the image (other programs don’t) and give me a good starting point for the white balance and channel swap processes. Picture controls do not matter as much if you do not use the Nikon programs to set the white balance. PhotoShop and other programs cannot access the Picture Control information in the NEF file and the images you bring into PotoShop may not  look like the images you see on the back of the camera. 

Please note that when you set the in-camera Picture Control to Monochrome, CNX2 to will present the image in monochrome. Monochrome images are often more difficult to modify in post. Fortunately, the NEF file still has all the color information and changing the Picture Control back to Vivid in CNX2 will give you an image that is easier to modify. If you shoot JPG images, you cannot make these adjustments.

Histogram:  My histogram settings are different from those described by many other IR photographers. First of all, I turn off the RGB histogram and shoot using only the highlight overexposure warning (blinkies) and luminescence graph. For my shooting, a balanced image is one where the luminance histogram is not bunched up on the left or right and there are no unexpected blinking areas (clipped highlights). 

Other IR photographers will tell you to watch the red channel histogram to make sure it does not get overloaded (really bunched up on the right). This does not apply when using most converted Nikon cameras because the best way to address an overloaded red channel is to adjust the white balance and I cannot do that in the camera. I have to rely on the RAW capture to collect all the color data and fix the WB (and red channel overload) in post. Watching for red channel overloading is important if you are shooting JPG or TIFF images because what you see is what you get and you have no way to recover lost image data. 

I use these settings on my 590nm SuperColor, 720nm Standard IR, and 830nm Deep Infrared camera conversions. All of these cameras (Nikon D90s) were converted by LifePixel.  

The following Nikon DSLR cameras can set a custom white balance after infrared conversion:

D40X      D80         D1
D50         D100       D1X
D70         D200       D2X
D70S  

Source:  LifePixel.com    

Sunday, January 12, 2014

Creative Infrared Photography - Low Key IR Photography

Low key is a photographic style that employs dark tones to create drama and depth in an image. Low key lighting isn't just about making dark image – it’s about selectively lighting the scene so that only specific areas are illuminated. Humans are creatures of the light and shadowy things emerging from the darkness give us pause. It creates tension and mood. Our eye instinctively moves away from the darkness to the brighter areas of a photograph and with selective lighting, the photographer can draw the viewer to different areas of the image.

In my normal approach to photography, I use fill flashes or reflectors to add light to dark areas.  With low key lighting, shadows become a major photographic element rather than a problem to be corrected. The selective use of shadows can not only add drama but it also bring realism to an image by creating three dimensional depth.

Greenhouse Path - IR Ann Arbor Michigan
Low key shooting is all about controlling the light. So what do you do when you cannot control the lighting in a scene? This is where camera settings come into play. The first image shows the main walkway of the greenhouse at the Matthaei Botanical Gardens in Ann Arbor Michigan. As I looked at this scene, I noticed that the lighting was mottled with bright and dark areas that would be a problem for normal photography. I decided to embrace the uneven lighting and let the sun puddles highlight different areas of the scene. To make this happen, I metered on the windows and invited the darkness into the scene.

This approach was not totally spontaneous.  My test shots showed that the poinsettias in the foliage would help to break up the mass of color on the left and the palms would provide some visual texture. So I went with it.  I also captured a 5 shot HDR bracket just in case my grand scheme did not work.  

My post-processing is described at the end of this article.  Nik Viveza 2 was used to add contrast and structure to the scene and Nik Define 2 was used to manage the noise. The final image was not quite dark enough so I applied a Low Key filter (dynamic low key) using Nik Color Efex Pro 4. 

Koi Pond -IR  Ann Arbor Micigan
The second image from this shoot shows the koi pool that is just inside the entrance to the greenhouse. A glass wall separates the reception area from the greenhouse and I was able to use it as a mirror to capture the reflections from the greenhouse behind me. Unfortunately, I could not capture the reflections and the pool in a single image because the dynamic range was too great. I shot a 3 image HDR bracket with exposures separated by 1.3 EVs. I set the white balance on the three images individually as described below.and I merged the balanced images using the Nik HDR Efex Pro2 software plugin in Photoshop. The channel swap was done on the HDR image. Once again, I was not concerned about the unevenness of the lighting.  It is what it is.  

Desert Plants - IR  Ann Arbor Michigan
The final image has low key elements but it may not be classified as low key by some photographers. This was taken in the arid desert greenhouse. One of the challenges a macro photographer faces in a greenhouse shoot is that all the plants are close together and it is difficult to get subject isolation. The foreground plant in this image was in a sun puddle and the background cactus was bathed with mottled light. The lighting made the texture of the cactus even more pronounced. This is not a good scenario for a macro photographer.
  
I could have blacked out the background in post but I wanted to try something different. By metering for the foreground plant, I was able to create a shadowed, dimensionally-diverse background. This background is too busy to please most macro photographers but I liked it because it kept my eye moving around the photo. The downside to this approach is that the photographic subject is no longer the foreground plant; it also includes the background elements. I’m OK with that.

All of these images were captured with a Nikon D90 with a LifePixel SuperColor (590nm) conversion and a Nikkor 20mm AFD at f/8. The initial white balance used the in-camera LifePixel preset. The final WB was set using Nikon Capture NX2 software and the channel swap was done in Photoshop CS5

Wednesday, January 1, 2014

Introducing Matt Murphy and His IR Event Portraits

My featured guest for this post is Boston photographer Matt Murphy.  If you have paged ahead, you will notice that Matt has been capturing some unusual infrared portraits at conventions and events.  I first saw Matt’s work in the Infrared and Ultraviolet forum at the Nikonians website.  

DW: Matt, these portraits are very creative and so much fun. How long have you been taking IR photos at events?
MM: Thanks Dan. Your interest in my IR portrait work is flattering, especially since yours were some of the IR images that convinced me to buy a converted body several years ago. My interest in IR portraiture came first, mostly from seeing some intriguing examples in the Nikonians IR forum site, and it occurred to me that conventions and other events would present particularly target rich environments. I went to my first event, a Steampunk Festival, early this spring.
DW:  Many photographers feel awkward asking strangers to pose for a photo. How do you approach someone at an event and ask them to pose for a photo?
MM: As do I in many situations, but asking someone to pose for a picture who has spent the last several hours assembling a costume and/or putting on elaborate make-up, etc.  is a pretty sure bet. These folks are, by definition, extroverts who are surrounded by fellow travelers and in their “happy place” so to speak and are often very enthusiastic about posing, especially when I tell them it’s for an infrared photo.


The Mad Hatter
Mad Hatter - Infrared - from Flickr
DW:  Let’s take a look at the Mad Hatter photo.  Can you tell us where this was taken and why you thought she would be a good IR subject? 
MM: You mean apart from the fact that she’s a beautiful young woman? (with jet black hair in the visible spectrum btw)  Seriously though, I liked her costume a lot and thought I could do something with the various textures (leather coat and hat, silk cravat, feathers, brass accents, etc.) that could set off the typical porcelain skin effect IR captures so well. She was a Steampunker and, like nearly everyone I asked, was very happy to pose for an IR picture or two.
DW:  It looks like you did a channel swap on this one.  Did you do any special post-processing on this photo?
MM: I did what passes for channel swapping in CNX2 on this one but, like most of my post effects, I did so selectively, swapping everything but the skin on her face which I found more appealing in the original configuration. One of the things I like most about IR in general is that you start off, out of the camera, with something that looks somewhat otherworldly, which I find frees me to do pretty much whatever I please to an image until I think it looks as good as I think I can get it and not give a thought to whether it looks “real” or not.
I went back to my RAW file on this one and saw that I had made 21 separate edits, almost all of them to only selected areas of the shot. I’ll spare you the details but for this one I brightened around her eyes, used a vignette filter (one of my favorite filters in CEP2), tamed blown out clouds, brass accents, etc. and, a must for any portrait, IR or otherwise, added some unsharp mask to her eyes.


DSC_4032
Boston Comic-Con - IR - from Flickr
DW:  The next photo is processed differently. I really like the tone-on-tone approach. It really makes the blues stand out.  Can you tell us something about this photo?
MM: These two women were at the Boston Comic-Con Festival last summer. I was working the line outside as the light was pretty even and I could control my backgrounds much better than inside.  As you noted, I didn’t do a channel swap on this one, probably because of the great blue hair on the woman on the right and what the original settings did for the skin tones of the woman on the left whose skin, in the visible spectrum, was distinctly copper colored. I added some skylight filter from Color Effex Pro2 to warm things up a bit then did my usual selective tonal contrast enhancements to bring out the clothes, accents and the like.I always keep any tonal contrast tweaks to a minimum on the faces as it tends to diminish that lovely effect IR captures give to skin.
DW:  Taking an IR photo is usually not a fast process because we use the JPG image and histogram on the back of the camera to verify the exposure and contrast.  Given these limitations, how do you efficiently capture this type of photo?
MM: After getting the initial permission, I usually start off by telling my subjects that IR does amazing things to skin and eyes but that, because different items reflect IR wavelengths differently and somewhat randomly as compared to the visible spectrum, it may take me three or four shots just to dial in the proper exposure. I typically do this via the exposure compensation dial while in aperture priority mode which, in effect, is altering the shutter speed. This lets them know that I’ll be taking a number of shots and tweaking my exposure as I go along so they know what to expect.

DSC_4018
Boston Comic-Con2 - IR - from Flickr
DW:  Boston Comic-Con2 is another great photo.  I love the sharpness of the leaves and the subtle coloration.  Can you tell us something about where this photo was taken?  Did this photo present any post-processing challenges?
MM: This is another from the lines waiting to get in to Comic-Con. Pretty standard post-processing treatment for me, meaning selective channel swap (excluded the face), a little skylight filter, vignetting, various selective tonal contrast boosts as well as the usual brightening and sharpening of the eyes. I was tempted to clone out the make-up on her right cheek but thought better of it when I realized it might have some significance to the character she was dressed as.

DW:  Skin tones and colors are so different in IR.  Do you let your subjects see the IR images on the back of the camera?  What do they say?
MM: I make it a point to show them the first decent exposure on the back of the camera to confirm that IR portraits are, indeed, like nothing they’ve likely seen before which also tends to pump them up a bit for the “keeper” shots to come. Maybe it’s because the folks who go to things like Steampunk Festivals and Comic-Cons are primed for it but they are almost always excited about how different the photos look and eager for me to take some more. You can’t really ask for much more than that when you’re taking portraits of strangers!

Mercury's Minions
Mercury's Minions - IR - from Flickr
DW:  This photo of Mercury’s Minions is striking.  I like this IR version much better than the visible light version in your Flickr gallery (I must admit to an IR prejudice).  Can you tell us something about this photo?
MM: Well, first of all I should tell you that I titled the photo before some friends who are “graphic novel” fans pointed out that this was clearly Hawkman and his trusty partner, Hawkwoman. Silly me.
This couple was at the Steampunk Festival and had one of the most elaborate costumes of the day. Their copper wings are folded away in this shot but were pretty impressive when I asked them to spread them for some visible spectrum shots. While they probably have too much covering their faces to be true portraits, I was again going for the different textures I was seeing in the costumes, knowing that IR would likely accentuate such details.
DW:  I noticed that your IR convention photos are taken outdoors rather than inside the venue.  Is there any special reason for that?

MM: Truth be told, I could say it’s the light, which is invariably better outside than the mixed, artificial sources you’ll likely find inside (pray for a cloudy day or find some open shade), or the ability to minimize background clutter which is nearly impossible indoors, but for events like Comic-Con which can get pretty pricey, it’s also about not having to pay for a ticket! In addition, working the lines of people waiting to get in allows you to tap into that excited, anticipatory vibe that can really animate a photo.
DW:  What type camera/lens combination do you use for your IR portraits?   Which filter did you have installed in your camera?
MM: I bought a converted D70s about two years ago and haven’t looked back. Standard 720nm conversion and I find the Nikon 18-200 VRI has the fewest issues with hot spots which, unfortunately, are a fact of life in IR photography.

Blue Eyes
Blue Eyes - IR - from Flickr
DW:  This photo of Blue Eyes is particularly endearing.  Can you tell us something about this photo? 
MM: She’s from the HONK! Festival in Somerville MA. It’s a self-described Lefty March Band convention/ festival with a big parade at the end. She was with her mother and sister in the marshaling area before the parade as part of the Free Tibet group, thus the native dress. With children, of course, you always ask the permission of the parent(s) but once secured, she had the same demure smile that I had noticed from afar. The blue eyes were a selective channel swap artifact but once I saw it I pumped it as much as I could without looking too artificial for my taste. Btw, her mother had the same, dreamlike look but for some reason I have none of her in IR.

One other piece of advice for shooting parades is to arrive early and work the area where the participants gather before the start. It gives you much more flexibility in choosing backgrounds and the like and allows some personal interaction that would not be possible if the subject was just marching by.
DW:  Can you tell us a little more about the selective channel swap you use with the Nikon Capture NX2 (CNX2) software?  

MM: I almost always try a red/blue channel swap in CNX2 just to see what I'll get. I'll often play with the Hue slider while focusing on different parts of the image to see what the swap does for skin tones, backgrounds, foliage, etc. Sometimes I like what it does to the whole image and other times I like the original look.  I often find I like the change in some areas but not others. In those situations I'll apply it selectively while still in the swap mode (LCH step) by using a + or - control point or, less often, the selection brush tool. The control point usually takes less work and seems to blend better than the selection brush when the area selected is markedly different from the surrounding areas such as the skin tones on a face.

If the control point leaves me with noticeable "spill over" in areas I don't want (hair, clothing, etc.) I'll often toggle on the "show overlay" effect in the selection section of the LCH step and then turn to the selection brush to clean up the edges by adding back what I took away with the control point (or vice versa).

I always make sure I start off with a correctly white balanced image before attempting the swap. As this can be a pain in the neck to get right in camera, I use the Set Gray Point/Marquee Sample tool in the Develop/Camera Settings section of NX2 to get a good base WB, then move on to the swap step.


DW:  This has been great.  Do you have any closing thoughts you would like to share?
MM: I’ve enjoyed it as well Dan. I guess the only thought I would leave you with is that the old saying, “it never hurts to ask”, is very true. I found it a hard lesson to learn but it has rewarded me on many occasions.
DW:  Matt, thank you for taking the time to share your infrared photo experience. These photos have inspired me to get to some of these conventions with my IR camera. 
You can find more of Matt Murphy’s infrared portraits at http://www.flickr.com/photos/28712192@N08/sets/72157634349843604/