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Producing Realistic Images with High Dynamic Range (Part 1 - Part 2 - Part 3 - Part 4)

Bracketing your shots

Most digital cameras have a feature called Automatic Exposure Bracketing (AEB). AEB is used to take a series of shots of the same scene in various exposure settings. Here are some guidelines on how to use AEB for optimizing images and creating a camera curve profile:

  • Preferably, mount your camera on a rock-steady tripod to minimize camera shake.

  • Set the camera to the Aperture Priority mode. In Aperture Priority mode, you will manually identify the aperture opening and let the camera automatically set the shutter settings. You can also set the camera in Manual mode if you are confident with your photography skills and dislike too much automation. Use a fixed aperture opening and assign varied shutter settings. Take progressive shots with increasing or decreasing exposure values.

  • Turn on the Automatic Exposure Bracketing feature of your camera.

  • To produce a wide exposure difference among your shots, take your shots with at least +/- 1.0 Exposure Value (EV). If your camera can only apply less than +/- 1.0 EV, take more shots until you cover a wide range of exposure.
Three shots can produce good results for producing an optimized image. More shots may result in too much difference especially if you cannot make the camera steady enough. On the other hand, if you are creating and saving the camera curve profile, five or more is the recommended number of shots.

Applying HDR to Bracketed Images
High Dynamic Range is best applied on bracketed images. Bracketed images refer to progressive shots of a similar scene taken in various exposure settings. You can use your digital camera to perform automatic exposure bracketing. For guidelines on how to bracket your shots, read the section entitled “Bracketing Your Shots”.

Step One:
Open the images that were taken using various exposure settings. Use at least three images like the sample photos in this tutorial.

Sample images    

Supposing you are behind the camera while taking these sample photos. The vast dynamic range, the gap between the extreme brightness streaking from the outdoors to the dark tones from inside the room, may confuse the light metering sensors of your camera. The metering may show a balanced value but the resulting photos reflect over and under tones in certain portions. To produce a realistic photo, photographers traditionally use a camera filter called graduated neutral density filter, which has to be screwed on top of the camera lens. But with the High Dynamic Range feature, you no longer need to buy that camera filter.

Step Two:
Select Format: High Dynamic Range.

Step Three:
Select Registration to allow the program to fix the registration of the loaded pictures. This is particularly useful for pictures taken without the aid of a tripod. However, it is highly recommended that you use a tripod to minimize camera shake. Select Auto crop after registration to merge images and automatically remove excess spaces. Click Preview to see the superimposed image in the Preview Pane. This image is merely a preview for you to check the registration and is not a preview of the HDR image.

Note: You will be prompted to remove images with identical exposure settings. In the Image List Panel, select one of the identical thumbnail images then click to remove it.

Step Four:
Select Auto Generate from the Camera curve profile to create an accurate camera response curve based on this set of images.

Step Five:
Click Compose to create the HDR image. This takes you to the Optimization tab where the HDR image is shown in the Preview Pane.

Step Six:
You can adjust the Coarse contrast setting from -100 to 100. But for the composite image in this tutorial, applying a value of 48 results in a more realistic image. The coarse contrast value determines the overall contrast setting. Details, on the other hand, allows you to make individual Highlight, Midtone or Shadow adjustments to bring out finer details in the light, midtone, or dark areas in the image.

Step Seven:
Click Save HDR Image to save the HDR image for future use. This opens the Save As dialog box which allows you to save the image in a destination folder in the .HDR format. Should you need to access this saved HDR file in the future, click Open HDR Image to browse for the image.

(Part 1 - Part 2 - Part 3 - Part 4)

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