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By Root 1945 0

time to put the experience into practice and go out and shoot some pictures. To avoid disappointment, I suggest you choose an easy subject to shoot first and follow the advice on the previous pages about bracketing and using a tripod with a cable release. You can certainly get successful results from shooting JPEG images, so don't feel you have to use raw, but in my view raw gives you more options, like the ability to pre-sharpen correctly and ensure the white balance is synchronized. The Merge to HDR Pro command can be accessed via the File Automate menu in Photoshop or via the Tools Photoshop menu in Bridge. I usually find it best to open via Bridge, since the image alignment is applied there automatically.

Response curve

Each time you load a set of bracketed images, Merge to HDR Pro automatically stores a response curve in Photoshop's preferences for every camera it encounters. As you merge more images from the same camera, Merge to HDR Pro updates the response curve to improve its accuracy. If consistency is important when using Merge to HDR Pro to process files over a period of time, you might find it useful to save a response curve (see Step 3) and reuse the saved curve when merging images in the future.

1.

The original pictures were bracketed using different time exposures at two exposure values (EV) apart. I began by opening a selection of five raw digital capture images via Camera Raw. It was important that all auto adjustments were switched off. In this example, I made sure the Camera Raw Defaults were applied to the first image and synchronized this setting across all the other selected images (you'll definitely need to check the white balance is included in the synchronization if the camera was set to use an auto white balance setting).

2.

I kept the images selected in Bridge and went to the Tools menu and chose Photoshop Merge to HDR Pro.

3.

This shows the Merge to HDR Pro dialog in 16-bit mode. Providing the 8-bit or 16-bit mode is selected you will see the HDR toning options shown here. These allow you to apply an HDR to LDR conversion in one step (the HDR toning controls are described more fully on pages 410-413). If you prefer at this stage to simply save the image as a 32-bit master HDR file, you should select the 32-bit mode, where the only option available is to adjust the exposure value for the image preview. There is also a fly-out menu in the Merge to HDR Pro dialog (circled below) where you can deselect the Automatic Response curve mode and also choose to save or load a custom response curve (see sidebar opposite).

Tone mapping HDR images

After you have created a merged 32-bit per channel HDR image, you can save the HDR master using the PSB or TIFF format to preserve maximum image detail plus any layers. Or, you can use the EXR format, which as I explained earlier is a more efficient, space saving file format for storing 32-bit images (but lossy). You can if you like skip saving the merged HDR image and jump straight into the tone mapping stage by selecting the 16-bit per channel or 8-bit per channel option in the Merge to HDR dialog. I think you will find though that there are some definite advantages to preserving a master image as an HDR file. There is a real art to tone mapping an image from a high dynamic range to a normal, low dynamic range state and you won't always make the best judgement on your first try. It therefore makes sense to save the HDR file first as a 32-bit master image and then use the Image Mode in Photoshop to convert from 32-bits to 16-bits or 8-bits per channel. This pops the HDR Toning dialog (Figure 7.5), which offers four methods of converting an HDR image to a low dynamic range version (see the sidebars on the left and the section below). With each of these the aim is the same: to squeeze all of the tonal information that is contained in the high dynamic range master down into a low dynamic range version of the image. Here I am mainly going to concentrate on the Local Adaptation method.

Merge to HDR Pro script

There is a ‘Merge to HDR