HDR: Processing with Photomatix

Posted by: In: Post Processing, Techniques 03 Feb 2011 Comments: 0 Tags: , , ,

This is the final installment in the trilogy of posts regarding HDR. It’s also the most complex (or simple!) depending on your point of view.

Part I: What is HDR? is available here.

Part II: Getting HDR Right In-Camera, is available here.

As a Photographer, I don’t want to spend hours in post processing. I want to get as much right in-camera, then do a minimum of work afterwards. In some cases though, a little more care is required.

The image below was shot at sunset in January 2011 at Castlerigg Stone Circle in the Lake District.

Castlerigg HDR at Sunset

For me, this is a lovely image of an iconic site (I would say that). But as with any photograph, miles of tweaking in HDR won’t help a badly composed  image. In this case, I avoided trying to take in the whole circle, and went instead for an angled view as the sun set with beautiful colours in the sky and on the stones themselves.

So. Where did I start?

I took the images 1/3 of a stop apart. The metering in this case indicated that 1/125sec captured all the wonderful sky detail, but nothing in the shadows. At 1/10sec, all the foreground was lovely and crisp, but the sky was a whiteout. In total, I took 12 exposures. Now this may sound a lot, but when you’re simply rolling the shutter speed wheel one click in between each shot, it doesn’t take long at all. In fact, with the inevitable cloud movement and the speed of the setting sun, haste was probably of the essence.

Which Software to Use With HDR?

Well. This will be down to your own personal choice. Photoshop comes with HDR built-in, and there are numerous software packages both as a free download and as a purchased option. I have tried free, and tried Photoshop, and none give me the level of control I need that Photomatix does. I have not invested any money in other paid HDR software packages, so I cannot comment on those, but if you’re thinking “I’m not going to grab this on one persons recommendation”, I agree completely and suggest you Google “Best HDR Software” or similar. Do it now. If you find a concerted group of people telling you something else is better, the rest of this tutorial won’t help much! However, HDRSoft do offer a free trial, which doesn’t expire or have limited functionality, but does put a watermark on your image. To have a play, download and try it. It won’t cost a cent/penny.

Now there are a LOT of people for whom “sliders” are things that need to be either completely on the left, or completely on the right. You may have seen those images on your search for HDR images. They are not for me, but some people enjoy that first “wow” when they blend those multiple exposures. When I first bought Photomatix, I did the same, and I now cringe at those early images.

It’s my very humble opinion, that if photographers say to you “Is that HDR?” because they’re not sure, then you got your processing spot on. You are trying to portray the full range of tones and colours from the brightest to the darkest areas, mapped evenly across your image.

Which version of Photomatix should you buy? Well that’s up to you. I have the standalone version because my computer is falling apart and can’t handle the RAM needed to run Lightroom, Photoshop CS3 and Photomatix all at once. It forces me to close other applications to get one running, and images bleed through on the screen from Lightroom into other programs. It’s not good… I also worry about having a version of Photoshop that would be incompatible with Photomatix. Having a standalone app, I need not worry. Your mileage may very well vary though. Final caveat: This tutorial is explained using the Photomatix standalone client on a Windows machine (Windows XP at the time of writing). Photomatix is available as a Mac version, and does appear to work under WINE for Linux users. More information on the latter is available under the FAQ heading on the Photomatix website.

Getting Started Using HDR Software

The first step, is to import your images into Photomatix. This is done easily with the “Load Bracketed Images” image button. You should then be presented with an option to browse your computer for the files. In the future, I shall be writing a Lightroom tutorial explaining how to set up the Photomatix import swiftly, as a separate guide around the Lightroom Export function (which is marvellous!). Photomatix can handle RAW files, but my experience is that it’s best to examine your files in a RAW viewer (I use Lightroom) and then export them as .tiff’s to a dedicated Photomatix folder.

Select your images (shift+click to select a group, or crtl+click to select individual images), and click “OK”.

You’re then given an option screen. Again, my experience with these may differ to yours but here’s what I’ve found.

  • Align Source Images. I now always use a tripod, so I know my images are aligned. If tree branches have moved, the software isn’t going to gobble RAM tying to align things. The only time I tick this box, is if I’ve shot handheld. Otherwise leave this unchecked.
  • Reduce Chromatic Aberrations/Reduce Noise. I always tick these two boxes. Photomatix are the experts, so I let their NR and CA removal tools do their stuff. For Noise, I leave the strength to 100% and set it to “all sourced images”. Depending on your camera, you may want to check the “underexposed images only”. I like to cover all the bases, and have so far experienced no ill effects.
  • Reduce Ghosting Artefacts. I leave this unchecked as a rule. At the “taking the photo” stage, I tend to compose to make sure moving things aren’t in the image. Tree branches swaying in the wind, people, water, clouds etc. If you have any of this in your shot, Photomatix will try and blend them together. For water and clouds, this effect is (in my mind) quite pleasing, but with things like cars and people, you end up with some ghosting that you will have to fix in further post processing. If you have movement in your shot, go ahead and check the box. I then strongly urge you to click “Help” and “User Manual” and read the section on Ghosting Detection. It’s very clever stuff…

Then click “OK”.

Eventually the tone mapped image opens on your screen and you’re ready to go.

The screen is split into three roughly speaking.

the main Photomatix window

On the left, you have the adjustments window, in the centre you have your image, and at the bottom, you have a presets window. A lot of the information on what does what is available in the manual (“Help>User Manual”), so go there in the first instance!

Presets are very straightforward. They consist of a collection of  “settings” to give a desired effect. Once you have found the perfect settings for an image, and especially if you take a lot of images in that style, it’s well worth saving the settings. They might not be perfect for every image, but it will give you a benchmark place to begin. Always save a setting if you like it! You can either save it during the Tone Mapping process, or once you’ve finished, so don’t worry if you forget!

With all the sliders and settings I mention below, one method I’ve found is to swing the slider all the way to the right, then all the way to the left, observing the change in the image. This gives you an idea of precisely what that slider does in terms of your image in particular. Play play play is the advice here. However…

I try to separate my workflow into distinct areas:

  • Tonal range (bright and dark areas as well as the contrast between them)
  • Colour
  • Detail

By concentrating on one thing at once, I find I tend not to get distracted with “slider obsession”. I also tend to look at an image with a fresh perpective when I tackle each area. I tackle “Detail” last, because the details slider can destroy an image, and by the time I get to that section, I’m getting very happy with what I’m doing.

Tonal Range

This is where you need the histogram. You’re looking for a range of tones from white through to black (in brightness terms – not colour!). Unless you have a particular artistic bent, a good rule of thumb is to try and get a good range. The majority of your tones should be in the middle of the histogram (which means they are “mid-tones” in the image) like this…

Example of toning in HDR

The histogram drops off at the left hand edge as you can see, indicating I don’t have much black in the image, so I need to start tweaking! But, out of the box, it’s a pretty good start. And it should be! Don’t forget, you’re blending a load of images with the end result of a perfect tonal range. You exposed for the highlights and you exposed for the shadows, and everything in-between, so when it’s all put together, you have a perfect exposure! (Well… you should have…)

For Tonal Ranges, the best tools are:

Luminosity (under the main header): General tone compression that tends to be an overall brightness modifier.

Smoothing (main header): This is the powerful one. It controls the smoothing of the contrast in the scene, and can be over-used. By all means use the “Light” mode, but this tends to give very surreal results – I prefer having the “Light Mode” box unchecked. It’s interesting to play with, but if you’re looking for an image that closely. By controlling the smoothing, you are varying the range of tones across your image. Every single image has a different look, and I’m sure you’ll find one you like. It’s the Smoothing slider that has a large degree of control over this.

Lastly…

White Point, Black Point & Gamma, under the “Tone Settings” menu.

White point increases the brightness of the bright areas of your image

Black point increases the darkness of the dark areas of your image

Gamma increases/decreases overall brightess

Initally, I would leave the luminosity slider, and use the tools in the Tone Settings. Keep an eye on the histogram as you make changes, as well as on your image. Remember one thing – if you like the look of it, then the histogram doesn’t matter. But if you aim to get the majority of the tones in the middle, you’ll be in a strong position.

Colour

Colour is the easiest to explain and controlled by the “Color Saturation” slider as well as the three sliders under the colour settings tab.

That’s it! I tend to use colour temperature to reign in any over-colour-toned images (shots that look overly warm or overly cool). The key here is not to overdo it. Tinker with the sliders to get the effect you want.

One important note here is for creating black & white. There are a myriad of methods for creating black & white images from colour, and the most common uses the channel mixer in Photoshop (or similar software). This changes the tonal range of every colour, based on the strength of that colour. So if you are going to go B&W with an image, my recommendation would be to increase the saturation to slightly “overcooked” levels . When you then get it into Photoshop, you have a greater degree of control with the conversion. As a quick example, here’s a church door before and after. Note how the “before” version looks very over-saturated, but that is completely lost in the B&W conversion which has a beautiful range of tones.

An image of a church door in HDR before black & white conversion

And after… (This time with cropping, a border and a clone out of the security light)

An HDR image of a church door after B&W conversionSo you can see that you need to keep thinking about your final image and how you want it to look, and not worry too much about how it looks in-between. “Never show an idiot a half finished job”, as my wife says.

Detail

On to the final part of the process. The detail slider is covered in many areas, and also has an affect on the tones of your image, so you may need to go back and tweak the tonal settings.

Strength controls the strength of the contrast between light & dark. Further to the right with the slider, and you get a very moody image. To the left, and it’s more ethereal and (in my mind) a little flat. I tend to have the slider on the right, past the half-way mark. But pay attention to what this does to the detail in your image!

Micro Contrast enhances detail by increasing local contrast. To this end, fiddling with this and pushing it too far right can leave you with black shadows. If you like this look, that’s fine, but if you don’t, and you want to keep these micro contrast settings, you may need to go and lighten image to compensate. With Photomatix in particular, it’s a careful balancing act.

And lastly, the Miscellaneous Settings. These all provide smoothing options, so if you want detail, they should all stay to the left. If you’re after a more dreamy look, then begin to push them to the right. However if you’re doing this on a landscape, watch your skies! The “Highlight Smoothness” slider can ruin delicate cloud detail very quickly, so that’s where you should be looking if you change anything here.

Now You’ve Accomplished HDR Processing!

At this stage you need to take a final look at your image and decide where you’ve gone too far. The temptation is to bring out all the colour and all the detail you have, but this can spoil the image. As with everything written here though, if you don’t like the effect, or prefer highly saturated images, it’s your show! After all, you are the artist.

If you like the final image, save the settings. I’ve found that different types of images need different settings as the light balance can change. Landscape and Interior shots benefit from having the presets saved, as well as shots you intend to B&W at a later date (over-saturated in colour). There’s nothing worse than having an image everyone says is wonderful, but losing the settings you had in Photomatix that created it. Save, save save. What’s the harm?

Once you’re completely happy, click “Process” and the software goes off to process your image.

Once that’s complete you now have the option to crop, resize and make other minor modifications to your image. I personally prefer to save it at this, and do that processing in Photoshop as I have more control, but it is good that these tools are offered, especially if all that is needed is a quick crop.

But… Before you shut the image down… (If you have ten more minutes…)

Click on “Process” and “Tone Mapping“. You can re-HDR your HDR image! This can create some really surreal and strong effects. Begin the whole process again! But remember to save before you start this as there’s now way to step back .

So that’s it! You have created your first HDR image. Hopefully this will inspire you to go and take more exposures. The key to HDR is getting the images in the first place. Capture a good range of tones in your original shots, and you’ll have a much easier time in the software afterwards.

Finally, it’s time to read the manual. I’m sure 99% of people load the software, play, then begin to ask questions without ever using the help button. The manual is extremely comprehensive and helpful and is a simple PDF rather than a complex search function that never returns what you’re after.

That’s not it from me on HDR, it’s just a beginning. There are numerous techniques for further post processing, and taking the shots in the first place, and I’ll be adding to this with new posts over time. Bookmark us, or follow us on Facebook (or Twitter once I figure out what to Twit).

At least visit HDRsoft and download the  free HDRSoft trial. Give it a go. You know you want to!

Ian

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