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HDR Tutorial part 2 - things to beware

Right… You’ve probably noticed by now that I am a fan of HDR. I’ll now try and share a few of the pitfalls I have found as I’ve messed around with it

1. Go easy, tiger…

The first few HDRs you make will probably be pretty extreme. As you get more used to the technique, you might find yourself getting sick of looking at your initial attempts, which could start to look a bit garish. Often the thing that draws you to HDR in the first place can become the thing that makes you hate it. I’ve found that mellowing my settings as I get used to the technique has helped my photography a lot.

The picture I posted on the main HDR tutorial is below:

Now - I included that because it’s a nice image, and it’s very obviously HDR. That’s both a good and a bad thing. For the purposes of a HDR tutorial, it’s good to see a shot that really shows off what HDR can do in an obvious way - but for me, I’d rather people looked at a picture and said “Wow, great photo!” rather than “Wow - great HDR!”.

The thing I’m trying to learn here is to use more the HDR technique a little more subtly, so I get an image I want without it looking outstandingly unreal or overprocessed. Whilst HDRs can look amazing, you do get bored of seeing them after a while, unless they are done with a little thought and style.

My second trip to a church, I toned it down a bit, and this is one of the images I produced:

Now - I think that’s a lovely image. It’s not as in your face arresting as the first one, but I think it’s a better photograph. Taken without HDR, it wouldn’t have looked half as nice - the windows and walls are completely blown out, and there is little detail in the roof ornaments and alcoves. But - looking at that image, I don’t know if I’d guess it was a HDR. Would you (a genuine question)?

That, to me, makes it more of a success. If I can take great photos that wouldn’t be possible without HDR, and make them so that first and foremost they are obviously a pleasing image rather than obviously HDR, then I am a happy chap.

What I do is have two saved settings in photomatix - one called “Extreme” and one called “Subtle”. Then, when I batch process a pile of images, I choose the one I fancy and see what comes out. If any look promising, I reopen the saved .hdr files in photomatix, and reprocess and tweak. Normally if a picture works in extreme, I’ll try it in subtle just in case, and vice versa.

2. HDR is no substitute for thinking about your shot

I am very guilty of this. Bang my camera on AV, set up AEB, frame what I hope is going to be a nice image and fire off 3 shots. Then move on to the next one.

This *can* work fine. But it’s really no substitute for stopping and thinking. Earlier this week I spent a glorious afternoon in dovedale, and 90% of my shots were ruined because I was too lazy and just did that. Look at this one for example:

The sky, as you can see, is completely ruined. This wouldn’t necessarily have been a good pic anyway, but if I’d thought about it a little, and then checked for blown highlights on the camera afterwards, I would have saved it.

I’ve made a little promise to myself that what I will do in the future is:

  1. Use manual mode with spot metering
  2. Consciously choose a point in the picture that I want to meter off, and meter off it
  3. Take the pictures, check them for blown highlights, and take more if need be

The first two things are what I should really always do anyway, HDR or not, if I am taking carefully composed photographs. There are occasions where AV, TV, P or even full auto are completely sensible - but if you are on AV and happen to accidentally meter off a dark log, your picture’s likely to suck.

In short, use your brain!

3. Don’t lose heart!

It’s very easy to look at other photographers work and despair because you see all their fantastic photographs, and then look at your huge pile of failures and know in your heart you’ll never be as good as them. But remember - all you see of other photographers work is the stuff they choose to show you. You see all your failures, and none (or few) of theirs. So don’t lose heart - remember everyone else is human too, and if you enjoy taking pictures, then keep plugging away, and you’ll improve.

It’s also worth remembering that some subjects will just not work as decent HDRs. It’s hard to really nail it down, but don’t be shocked if lots of your images just look terrible, no matter how much you twiddle. It’s partly suitability for the medium, and partly just some photographs will always look lame. Everyone takes them, so don’t let it bother you. Concentrate on your successes, and try and learn from your failures.

I myself go through phases - a bit like a sine wave of confidence. I start off thinking I’m crap, then go out and try really hard and get some good photographs, then start to get more confident. I get more and more confident until I get lazy, and then I take a whole pile of terrible photographs and think I’m terrible again. Which makes me try harder, and the whole cycle continues.

I take AN AWFUL LOT OF PHOTOS. I probably put 10% up on my flickr account. Perhaps 2% of them get on here. I suspect most “serious” photographers do the same - you get a good eye for what you like, and become quite severe when throwing away the dross.

Posted in tutorials. Tagged with .

By Dan
January 10, 2009

39 comments

HDR Tutorial

The software I use for all my HDR work is Photomatix Pro by HDRsoft. If you’ve come here looking for my 15% off discount code for photomatix, you can find it here.

HDR (High Dynamic Range) photography is gobsmacking when you first see it done well - but the lack of simple tutorials meant it took me a long time to really understand how it was done. This is my attempt to help other people in my situation by creating my own HDR tutorial.

The purpose of HDR photography is to show a higher range of detail than could be possible from a single image. When the human eye scans a scene, the pupil dilates and contracts, enabling us to quickly flit around the image and perceive detail in all but the brightest and dimmest conditions. When taking a photograph, the camera (or the operator, if it’s in manual mode) has to decide what length of exposure to use in order that the important parts of the picture retain detail.

When using raw mode on a DSLR, the image can be pushed about a stop of light* either way (brighter or darker) without significantly affecting the image quality - which, whilst better than you would get from a JPEG, is not enough under most conditions to allow detail throughout the scene.

* This terminology can be confusing. “A stop” is basically twice or half the amount of light hitting the sensor. So, if you had a properly exposed image, then an extra stop of light is twice as bright, and one stop less is half as bright. Stops aren’t to be confused with “clicks” on the little wheel you rotate - that can normally be adjusted in the camera’s functions to go 1/2 or 1/3 of a stop each time. You can adjust the amount of light hitting the sensor by either changing the aperture size or the exposure length - for HDR, you must only change the exposure length between shots, as changing the aperture size will affect the depth of field of the image and stop the images stacking up correctly.

A sample image

If that had been taken from a single exposure, I couldn’t have packed that much detail in (without a lot of filters and post processed jiggery pokery, at the very least).

Obtaining the image

You can take as many as you want - I normally use Auto Exposure Bracketing - a setting your DSLR probably has, which enables you to take three pictures in quick succession (I have it on multi-shot mode, so I can just hold down the button and it takes all three) at a set range of exposure times. The 450d (and 350d/400d) allows you to go up to two stops either way. This is a bit of a shortcut - the longer way to do things is to adjust the exposure time manually, and take as many pictures as is necessary to ensure you have one with no blown highlights, and one with no blown shadows - how far you go is up to you, and the effect you want to achieve - the only stipulation is that the pictures must be even steps apart (eg. 1 stop, 2 stops etc).

*NOTE - I’VE RECENTLY LEARNED THAT THIS ISN’T TRUE.  THE IMAGES DON’T HAVE TO BE EVEN STEPS APART.  SO YOU CAN WING IT A LITTLE :)

Also, whilst you can make HDRs with JPEGS, I would suggest there’s little point. I got into the habit of always using raw a while ago - it makes for better HDRs, and gives you more control over your final images.

For the image above, I used auto exposure bracketing, and I didn’t have my tripod with me, so I set the aperture to f/11, and the iso to 200. Normally for a landscape shot - especially a HDR - I would go for iso 100, f/22 and a tripod - but sometimes you find yourself in front of a nice picture in the right light and just have to make do.

Also, I’ve found when I’m going out with other humans it’s much better to not take along a tripod and pile of kit unless they are camera geeks too. It’s a tragic sight to see an excited photographer setting up all his gear next to a babbling stream, as a wife and family look on, bored to tears by the whole thing. Save that for when you’re out on your own, and try chancing a hand-held or two!

Then I leant on a sign to give myself some extra stability, and fired off three images:

1) Normal image:

2) Two stops below :

3) Two stops above:

Here are the three original raw files from my Canon 450d that I used to create the above (you might want to right click + save as, or ctrl+click/save target as for macs). You could use them along with the free demo of photomatix to have a play around.

056.CR2 (normal image) - 21MB
057.CR2 (-2 stops) 17MB
058.CR2 (+2 stops) 22MB
autumn.zip - a zip file of all three - 57MB

Creating the HDR

Once you’ve got your raw files into your PC, you need to convert them into a HDR. I can only really discuss Photomatix, as it’s the only software I’ve used. But I can say that I like it - I bought at the beginning of 2008 think it’s great. I have arranged a discount code you can use to get 15% off.

Open up photomatix and drag your raw files onto it, or open them up via the menus. Choose “Generate an HDR image” from the dialog, then OK your image list, and you should get to an options menu that looks something like this:

 
dialog from photomatix
 

If I have handheld the shots, I always choose align source images (trying first matching features, then horizontal/vertical shifts if I don’t like the result).

I always choose reduce noise & chromatic aberrations.

In this case, I chose to reduce background movements, because there were leaves and a breeze in the picture. This and the objects/people option can sometimes work very well, but don’t rely on them - it’s much better if you have no movement in your picture.

Once you click OK, it will start to chug away and create the initial HDR file. It will look AWFUL - something like this:

ugly HDR file

Don’t be put off. This is just a simple attempt to show you the contents of the file - it hasn’t been processed at all at this point, and contains more detail than your monitor can display. The next step is when you turn this HDR file into your final image.

Producing your final image

Once you’re at the stage of looking at your ugly HDR, you should see a TONE MAPPING button on the left. Give that a prod. Your computer will chug for a few moments, and then you’ll be presented with the image as processed by the default settings (or, if you’ve used the program before, your previous settings).

Sometimes, your image will look great straight away. Sometimes it’ll start off looking awful, and no amount of twiddling will save the day. More likely, you’ll have to mess around with the sliders and options until you’re happy with the result.

The settings I mainly fiddle with are pictured below (ie I don’t tend to play with tone compressor / colour settings / smoothing settings much - sometimes, but not as a rule):

settings from photomatix

Those are the default settings. I am, admittedly, a bit of a colour freak - so it’s quite often that I’ll start off by whacking strength, colour saturation, luminosity up to 100% - and then light smoothing to high. Without light smoothing on high, I find I don’t like the look of “haloing” you can get around contrast boundaries.

The “White point” slider chooses the point in the image at which highlights are allowed to blow out. If you slide it to the right, your image generally lightens (but you can lose detail - not always a bad thing) - and to the left, it darkens.

The “Black point” slider is the same, but for the shadows.

“Gamma” is a little like “Fill light” - it brightens or dims the whole scene.

I generally find I can make an image look nice (if it’s ever going to look nice) with a combination of these sliders and buttons. If my initial 100% stab looks awful (it often does) i try for a more subtle approach, twiddling things around until I like them.

For the image at the top of this tutorial, I used approximately:

Strength: 100%
Colour Saturation: 64
Luminosity: 10
Light smoothing: high

White point: 0.250%
Black point: 0.000%
Gamma: 1.01

And bingo - I liked the look of it, so I pressed “Process”, and then I had my final image:

Which I think came out rather well! Feel free to try and better it - sometimes a much subtler approach can work wonders.

Have fun playing around - if I can be of any assistance, do ask. Or, if you have any tips or suggestions for me, I’m all ears. I’m far from an expert on this stuff!

Part 2… things to beware

Posted in tutorials. Tagged with , , .

By Dan
October 30, 2008

121 comments