From Conception to Completion – A Basic HDR Workflow Process By James Pawlowski
The human eye is a marvellous piece of natural engineering far more advanced than anything man can produce with current technology. In years gone by, it would slightly frustrate the perfectionist in me when some of my drawings or photographs did not 100% replicate the amazing things I was seeing. Then I came across High Dynamic Range photography. Many thousands of words have been written on the subject of HDR, both in support of it’s amazing abilities and deriding it as a bastardisation of traditional photographic techniques, or as a form of photographic ‘cheating’. However from my perspective, HDR is just an extension and development of techniques that have been practised by the world’s best photographers and printers for many years. Many of the principles that I learned as a junior photographer using film and the chemical print process, still have as much relevance today in the digital age as they did during the previous era. Exposure bracketing, masking, feathering, softening, sharpening, dodging, burning, mixing and striving for greater tonal range and less noise are not, and never have been, exclusive to digital photography or HDR. This is because the principles of great imagery have, and always will remain the same. At the end of the day the only thing that matters is the end result, and for me at least, the emotional relationship that the viewer has with my work.
Above: An image I have a great affinity with, representing my time living and working in South Korea.
The Shooting Process
For me, the process of creating a good image is all about the emotion that goes into it. If I do not have an emotional connection with my own image, then how can I possibly expect the viewer to have one? To form an emotional connection, the shot must be composed so as to fuel passion in me. My grandmother used to say; “You can’t make a silk purse from a sow’s ear”, and this old idiom rings very true for any type of photography. The composition and technical aspects of creating the raw images, such as exposure, focus and depth of field are the most important part of the entire process. Without interesting composition of the subject and attention to detail in this first step, you will not achieve the results you are looking for. No matter how good the software is; an essentially bad image cannot be turned in to a good one, even with today’s technology. Take it from someone who has tried.
To produce a true HDR image, you must shoot a set of bracketed images. Bracketing is when you shoot a set of three, five, seven etc. images of the same composition with a correct exposure as the base image and then under and over exposed shots either side. You can add as many under and over exposure images at various stop (+/-) intervals, as you like. The more you add, the greater the tonal range you will capture and the more detail the software will be able to collect for your final image. An example of a five image bracketed set would have the following exposure values, with 0 representing the correctly exposed image, + the over exposure, and – the under exposure. -2, -1, 0, +1, +2.
I use Canon Cameras and lenses. HDR photography can be made using any camera that has a manual mode or a bracketing mode, however, that is not to say that any camera is ideally suited to HDR photography, Canon cameras among them. They are not. One of the biggest drawbacks with the EOS system is Canon’s refusal to allow auto bracketing of more than three frames on any body less than the flagship 1D range. Even with the 1D range you only have a maximum exposure time of 30 seconds before having to switch to bulb mode. This causes the HDR photographer many problems, not least of which is having to constantly touch the camera during the critical exposure stage, risking knocking any number of settings or the composition off.
To overcome these problems, I use a cheap and simple solution that is aimed at both the professional and hobbyist alike, called Triggertrap. This is a downloadable app for the iPhone, which costs about $10.00. A dedicated cable for your camera must also be purchased, which costs around $20.00. At $30.00 for the complete package, this system is a far cheaper alternative to the dedicated exposure-control units, which retail at between $300-400.
Caption: Left: long Exposure HDR control Screen in Triggertrap. Right: Triggertrap’s menu screen, detailing just some of the many options.
You can find out more about the Triggertrap here: https://triggertrap.com/, but it basically allows the user to take a set of up to 19 bracketed exposures at various stop intervals over very long exposure times, controlled from your iPhone (I think there is an Android app too) rather than from the camera. Triggertrap offers many other options for different types of experimental photography as well, but these are too numerous to go into in this article and would take up a whole separate review to do justice to.
When shooting I tend to take as many exposures as I deem necessary for the subject. If it is an urban image with hundreds of flashing billboards, which are six stops brighter that the main body of the image as in the example below, I will allow for that in my exposure range and shoot a fifteen exposure, bracketed set at 1 stop intervals in order to have the ability to mix the correct exposures into my final image.
Above: An example of a situation where a greater range of bracketed images may be necessary.
For general landscapes or cityscapes though, I tend to find a five or seven exposure set at 1 stop intervals is more than enough to get the tonal range I require. Each situation is different, and just because you shoot a fifteen exposure set, does not mean you have to use them all when it comes to the processing stage.
However, one thing that cannot be changed that easily is the composition. As I mentioned earlier, the importance of composition is the critical factor in any type of photography and I cannot stress how important this step is. In composing my shots, I tend to compose, and then come away from the camera to do something else like the exposure settings before looking at the composition once more just to check I am happy with it. I try to visualise the finished image and shoot accordingly, setting my aperture to give the correct depth of field and finding a focus point where that depth of field is maximised. For general landscapes I usually use f16 and 100ASA to get a good all round depth at low noise without softening the image. I also use manual focus to stop the camera hunting for focus between frames.
Experience has also taught me to shoot the same subject from as many different angles as I can, using different focal lengths, so as to have a range of different composition options where possible. There is nothing worse than sitting in front of the computer after the fact, looking at an image on screen and thinking I wish I had done this or that, but didn’t. This is obviously not always possible, especially when you are shooting in rapidly changing lighting conditions, but my advice is to just do what you can, when you can and get the best out of each situation. Every photographer has their own shooting style and process for getting the best out of each shot, so I am not going to go into much more detail here, as it would be a little like teaching my grandmother to suck eggs. However, you can also help yourself in the post process workflow by noting down the frame numbers of each image set whilst on location. This simple step can save a lot of headaches when it comes to sorting through two or three hundred images of various exposures and slightly different compositions.
If you want to download the files to follow along with this part of the article, please feel free. Click on the link and download all the images in the folder.
You will also need to download the trial versions of Adobe Photoshop CS6 (the plugin will work with CS3 upward if you already have any of those package), Photomatix Pro and Topaz Labs Photoshop plugins from the links below.
The image we will be using is a seven exposure shot of an urban river scene shot during blue hour (the hour between sunset and full darkness). The middle exposure is a 14 second exposure, shot at f16 on 100ISO. I tend to use my camera permanently set on a cloudy white balance setting, as this tonality suits my photographic style. This is the finished image.
Now you have your raw image files, it’s time to turn them from RAW‘s into an HDR image. To start with I use Abode Bridge to view all of the images that I have shot in the series.
Above: A screen shot of Adobe Bridge.
The image that I want to process usually stands out a mile, even as a thumbnail. However, I try to resist the temptation to dive right in on processing that one image and look through everything. Once I have selected the various images I am going to process, I refer to my notes to find each image in the bracketed set and divide them into a separate, labelled folder. It is handy to have a dedicated folder where you can put everything referring to that one image set, so that once everything is complete; it slots neatly into a filing system.
I usually use one or both of the following software packages, Photomatix Pro and the HDR software built into Photoshop. In general I lean towards Photomatix, but Photoshop offers some features that Photomatix does not, such as the ability to pick a key frame. This is especially handy for HDR shots of constantly moving subjects such as traffic, so that you can choose the best frame to base your image upon. The two packages also give slightly different results and tonal ranges, which I have used in the past to process different parts of the same image. For this article we will only be using Photomatix Pro for the actual HDR process on the image, followed up by using Photoshop to fine tune.
On loading Photomatix, go to file > Load bracketed photos. Navigate to the folder you created containing the set of images to process, select and press load. On the Mac, you can also just select all the files directly from the folder and drop them onto the Photomatix logo in your dock.
Above: The ‘Preprocessing Options’ box in Photomatix.
The first menu you are presented with is the Preprocessing Options box. If you have never used Photomatix before, the number of settings can be daunting on first glance, but don’t worry. The great thing about HDR processing is that you cannot break anything. All your original files remain untouched and if you make a mistake, you can always go back or start over again. Other than adding a little more noise reduction, I use pretty much the default settings. However, make sure that the “Remove Ghosts – with Selective Deghosting Tool” box is checked, as that is the next step in this process. To continue, press the ‘Preprocess’ button.
Above: The Selective Deghosting box in Photomatix Pro.
After the computer has churned away for a few seconds, you will then be presented with the Selective De-ghosting Box. This is a really handy feature of the Photomatix software. Due to the very nature of mixing five separate frames to create an HDR image, anything that moves, from people and cars to trees or water, will ghost. Ghosting is when you have a moving object repeated in different places within your image and is often unsightly if it is not part of your planned artistic process. The de-ghosting tool can therefore save you many hours in Photoshop removing unwanted ghosts. It is also easy to use. Use the zoom slider to enlarge the image and identify the areas you want to de-ghost. You can correct the ghosting by roughly drawing a line around the affected areas. The software will do the rest.
Another kind of ghosting is caused if a strong light source is not constant across all the frames in your set, for example a car trail. The software will leave the outline of the trail or highlight, but mix the dark background into the middle of the highlight. The de-ghosting process grabs the selected part from just one image in your set and usually mixes it seamlessly into your image eliminating the problem, although this is not always infallible, as we will see later in the process. You can select multiple areas to de-ghost and preview the results using the ‘Preview’ button at the side as many times as necessary. However, once you click OK, you cannot go back and select more areas without starting the process over again. Once you click OK, don’t worry if the processing time takes a while, as the bigger the images, the more time it can take, and even with a quad core computer, this can take some time.
Above: The main menu screen in Photomatix Pro
Now that all the pre-processing is done, you are finally presented with the main HDR options page. The first thing to do here is hit the default button toward the bottom of the menu, to reset all the sliders. As with the pre-process options, the number of sliders and options in the menu can seem daunting, but as I said earlier you cannot break anything, so just play around and see how adjusting each slider affects the image. I personally only use Photomatix to make a rough working image that can then be fine tuned in Photoshop, so don’t worry too much if you cannot get the exact colours and tones you want at first, as this can be corrected later in the process. Each image requires a different range of settings to achieve the required result and it is rare that two separate image sets will require the same settings. The sliders I use the most are the Strength, which controls how much detail and main contrast you want in the image, the Colour Saturation, which controls how much or little colour, the Detail Contrast which is like a regular contrast tool and works better on some images than others, and the Smooth Highlights slider, which will alter the amount of stark contrast between light and dark areas within your image. I, like most photographers, taught myself to use Photomatix by a system of trial and error and I would encourage you to do the same as it allows you to learn exactly what effect each slider has. However, if you want a more detailed description of what each slider option does, here is the link for the Photomatix Pro manual:
When I am processing an image, my personal preference is to try to get it as close to the colours and tones that I could see on location. However this is not everyone’s HDR style and there are not really any right and wrongs here, as like any art form, imagery is subjective and it only matters that you like what you are producing. In saying this though, general opinion has it that ‘Halos’ are not a good thing and take away from, rather than add to, the finished product. Halos are areas within the image that have a slightly different tone from the rest of the image and lack the detail you are striving for. They tend to occur where the sky meets the ground or around the edges of buildings, as in the illustration below.
Above: An example of the HDR Halo effect, usually to be avoided at all costs.
Some images are more susceptible to haloing than others. The image we are processing for this article would not halo, even for demonstration purposes, so I have illustrated the effect with a different image. The easiest way to avoid halos is to back off the strength of your HDR (the first slider in the menu), and then use the micro smoothing and lighting adjustment sliders to try and eliminate the halo altogether. However, this method may still not be enough, especially if you are trying to achieve a certain effect and at that point, you will have to revert to using masks and other Photoshop based methods to eliminate the problem.
For the purposes of this article these are the slider settings I used:
Colour Saturation: 57
Detail Contrast: +4.4
Lighting Adjustments: (Check the lighting effects box) Medium.
Just leave everything else at default. Once you are satisfied with your selections in Photomatix, hit the process button at the bottom of the menu bar. The software will then complete your selected processes before presenting you with the final working image. Go to File> Save As. Name your working image and put it in the folder you made for this image group earlier. You can also check the option to directly open the image in Photoshop after saving.
If you prefer, you can download the file I outputted, from Photomatix, for this article here and move straight on to the Photoshop stage:
Please feel free to change the image in any way you want. I would be really interested to see other people’s interpretations of my imagery, so please send me your finished product.
The final steps that I go through are all completed in Photoshop. Open the image in Photoshop, click straight through the Camera Raw options box that pops up (Your version Photoshop may or may not be set to open all images through Camera Raw. Don’t worry if the image opens without the camera RAW box popping up first). When the image is open, the first thing I do is to see how it looks by applying the Auto Tone option in images menu.
Above: The Image menu in Photoshop that includes the Auto Tone option.
Some times this option removes any slight colour casts and helps the image to pop, and sometimes not, instead giving colours and tones miles away from what you are looking to achieve. In this case it works well so leave it. If you decide you don’t like the auto tone, then simply undo it in the Edit menu. After this, I head to the Topaz Labs plugins in the Filter menu and select Topaz Adjust.
Above: The Topaz Labs menu in the Filters menu of Photoshop.
I highly recommend the Topaz Labs software, as it is just as useful for non-HDR images and in the web design aspects of my work as it is in this process. It allows the user to change just about every aspect of the image, from just making it pop to making a fully surreal or cartooned image. I am not going to go into too much detail here, as there is a fuller review coming soon, so I will just go through the steps needed to complete this image.
Just as in Photomatix, the key to Topaz Adjust is to play around with the many settings to see just what they do. If you don’t like the final effect you have created, just undo it in Photoshop and start again. While this can be time consuming, it is well worth the effort, as an effect you may not like for one image, may suit a different one from another image set.
Above: Topaz Adjust menu box
Essentially, Topaz Adjust drags out far more latent image information from your HDR image than the initial Tone Mapping process in Photomatix and allows me to get my image to as near as what I saw when shooting as is possible. To start with, use the Adaptive Exposure slider. This control is similar to the Strength slider in Photomatix, but has a far greater effect on the image depending upon where you position the sliders. The Adaptive Exposure slider works in conjunction with the regions slider. The regions slider determines which parts of the image the Adaptive Exposure filter affects. For this image, I will use the Adaptive Exposure setting at 0.30 and the Regions Slider at 39. In my opinion, this particular image needs little else at this stage, however, you may want to protect the shadows from darkening any further with the protect shadows slider and the same for the highlights. Please feel free to play around though and get a feel for what the software can do. Once you are happy with the low-resolution preview on screen, press the okay button and the image will process before taking you back to Photoshop. As Topaz accentuates the colours and the HDR process, any flaws in your image, such as dust on the camera sensor will also be accentuated, and stand out a mile. Don’t worry about this, as we will deal with it later in the process. We will come back to Topaz Adjust at the very end of the process for one last procedure.
Above: A before and after using Topaz Adjust.
Above: The adjustments menu in Topaz De-Noise.
The next step requires you to go back to the Topaz Labs menu, and this time select Topaz De-Noise. The HDR process creates masses of noise, and while the newer cameras are great at suppressing it, the tone mapping and Topaz Adjust process will bring out any noise that remains as well as creating its own. I like to try and remove noise at this point as the next steps involve detailing and sharpening and I always find that noise is harder to remove beyond after these processes. Noise is basically thousands of little dots of colour in the image that do not truly match the main tones of the image. I try to use as little noise suppression as possible as it does soften the image slightly. At the bottom of the menu box are the Recover Detail and Reduce Blur sliders. These allow you to retain some of the sharpness of the image while still reducing the noise. For this image pull the Overall Strength slider to 0.3, the Recover detail slider to 0.33 and the Reduce Blur slider to 0.37 and then press OK. As with all HDR software, De-Noise requires a process of playing around with it to find a sweet spot for each image.
Now go back to the Topaz menu and select Topaz Detail. This plugin is great as it allows you to crisp up all the edges and details that have been made soft throughout the HDR process.
Above: The adjustments menu in Topaz Detail 2.
Topaz Detail can produce some amazingly surreal results and has a set of pre-sets that will give you an idea of what the application can achieve. However, for this type of photography I really only use it to recover some of the lost detail in my shot and to make everything in the image pop. The temptation here is to over process the image and make it un-naturally sharp, so blow the image up to 100% using the button at the top of the menu and check each element of the image as you make adjustments. If you think something is “overcooked”, back the sliders off. There is also another de-blur option and I use that in conjunction with the main detail sliders to achieve optimum results. I also use the Protect Shadow and Protect Highlights sliders to make sure that areas of little detail don’t go a deep black and areas of highlight remain white. Here are the settings I used for this image:
Small Detail 0.00
Small Boost 0.14
Medium Detail 0.00
Medium Boot 0.00
Large Detail 0.18
Large Boost 0.06
Protect Shadows 0.07
Protect Highlights 0.18
De-blur Strength 0.12
Now the image is very nearly finished, but by this time, that censor dust that I mentioned earlier is nearly jumping out of the screen and smacking you around the face. Time to deal with it. There are many ways to deal with dust in Photoshop, but I use the patch tool. Select the tool and draw a tight selection line around the affected area. I use a Wacom board to do this as it allows me to be more accurate, but just using the mouse is fine too. When the selection is complete, drag the selection a tiny amount toward the part of the image you want to replicate. This then seamlessly covers the dust spot. Repeat this process for all the dust spots until you have eradicated them.
Above: A before and after shot of dust removal using the patch tool in Photoshop.
At this stage I also blow the image up to 400% and look for other imperfections from the various processes that need correcting. It is a good idea to examine the each part of the image and use the patch tool or the clone brush to make any corrections that you feel are necessary. While these imperfections will not really be seen when the image is relatively small, if you plan to print a large version, they will show up. Correcting imperfections can be tricky and it basically takes practise and a lot of patience. Most of the imperfections will occur around the highlights as in the image below, but that does not mean other problems are not lurking in the shadows. To correct the problem that I have illustrated below, I would try to find a part of the same trail the is unaffected by the ghosting and clone that into the effected areas.
Above: A light trail in the image that was not caught by the de-ghost feature in Photomatix.
One last addition to the image is a vignette. To do this I use Topaz Adjust again. Reopen the plugin as before and hit the Reset All button at the bottom of the menu bar. If you do not do this, your previous adjustments will be re-applied to the image, creating a far different effect. Click on the Finishing Touches menu and then Vignette. Adjust the Vignette Strength slider down for black vignette and up for white vignette and then fine tune with the feathering options below. How you apply the vignette is purely up to your own artistic interpretation of the subject matter and what you think best.
Above: Applying a vignette in Topaz Adjust.
Now have a finished HDR Image. Although I don’t think this image requires it, if I was going to add further sharpening I would use the Topaz In Focus Plugin, which allows for far more control over the sharpening process than the Photoshop options and provides crisp, clean results.
Above: The Finished image.
I hope that this article has been of both interest and help to you. Please remember that this is only a basic HDR workflow, and there are hundreds of different processes that you can use to get the best from your HDR images, many of which have or will be highlighted by the talented photographers of HDR One. The key to constantly improving your photography is to keep an open mind and to never stop learning.