In the article on shooting high dynamic range (HDR) photos we showed you how to expose for a church. Now, with the resulting 4 photos we will merge them using Oloneo's PhotoEngine HDR program.

The current beta release of Oloneo PhotoEngine is free to download so anyone can try this technique - all you need is an exposure bracket.

Step 1: Browsing the folder of photos

Open PhotoEngine and click on the small Select Photo button (1) top centre in the browsing window. Navigate to your folder of images and click open. All the photos from the folder appear in the preview window as thumbnails. The size of the thumbnails displayed can be adjusted using the slider (2) top right of the browsing window.

Step 2: Add photos to the Project

Click on the thumbnail of one of the photos you want to use in your HDR bracket. And then hold down the ctrl key or shift key and click further photos from the bracket. You will see a green frame appear around each photo to indicate it's selected. Go to the Project Image Selection and click Add and your photos will appear in the window ready for processing. Shutter speed and aperture details will be displayed alongside so you can compare exposures and decide if the selected photos are the correct ones.

Step 3: Create the HDR ToneMap

Now look at the HDR ToneMap box below the Project Image Selection box. If you used a tripod when taking your bracket you don't need to use the Auto Align feature, so leave this unticked and click on Create HDR ToneMap project. PhotoEngine will then start to process the images. This takes several seconds and then opens up the merged image in the centre window, with a selection of controls on the right and a history (called Time machine) on the left. The merged image probably won't be looking too good at this stage. It's the sliders that will show the true potential of HDR processing.

Step 4: High Dynamic Tone Mapping

The first set of grouped sliders is the High Dynamic Tone Mapping group. These are the  only ones we will use for this tutorial. The first item is a drop down menu for the type of tone mapping control you want. It's preset at Local Tone Mapper, but there's also Auto, Advanced and Global options.
Auto is a single slider control that makes it easy to adjust, strength but the flexibility of balancing light and dark areas is limited. Global is a two slider control which gives slightly more flexibility, but it's much better to use Local which provided five controls, or if you want extreme power go for Advanced with eight sliders.

The first two sliders adjust the ToneMap detail and strength. It's these that give the recognisable cartoony effect that so often turns people against HDR, but at the same time, if used well, can be very effective.

The exposure and contrast sliders will just emphasise the cartoon or realism.

Choose the right subject and get the balance right with these sliders and the cartoon-style can be very well received. However if you're looking for a more realistic merge of tones make sure you use these sliders with caution.

As you can see from the two pictures below the result can vary widely. First is with the TM Strength at maximum and the result is very unrealistic, while a more subtle tone map can be created when sliders are used with care.





And the version I decided on, with a slight rotation and perspective control using Photoshop after the Tonemapping was done is this: