It is normal to use a series of bracketed photos a the basis fro creating the HDR image. However, as we saw in in Digital Photography Tips on Pictures for HDR Photo Software, the standard technique is to use tripod and choose stationary objects and landscapes to create three or more pictures with identical subjects and only the exposure altered.
Bracketing Shots and Moving Subjects
Moving subjects create a problem, especially something moving as fast as a field of thoroughbred racehorses just out of the the starting barrier. It is impractical to get three shots without the horses galloping into the distance and well out of shot.This where the single image technique becomes useful.
The sample shot is the classic dynamic range problem, a bright sunny day and the restricted shooting position that is partially towards the sun, so the horses are in their own shadow. The normal solution is to meter for the horses body, resulting in the lighter background being overexposed and washing out.
The RAW - HDR Solution
The is HDR solution is to shoot in RAW and then create the extra images from the original in post processing in the RAW converter. The example shot used centre weighted average metering resulting in a good overall exposure but the horses were darker due to the shadow effect from the angle of the sun., while the track in the background is well exposed.
Simple Easy HDR Workflow
You don’t have to be a genius with photography editing programs to produce an improvement over the original digital photo with HDR processing. This description of the basic workflow in photo software of the race horse digital photo from a RAW image to an HDR jpeg.
In the RAW converter three 16 bit tiff file format versions were produced, one at the exposure setting as measured by the camera, and two with exposure adjusted using the exposure adjusting slider in the RAW converter to give two stops of under, and over exposure. This adjusts the exposure for the darker and lighter areas of the image, particularly the main subject, the race horses.
The three intermediate tiff files were then loaded into the de-facto standard HDR image software processing package, Photomatix, to produce the HDR image, and then tone mapped to produce a readily viewable tiff format image.
One problem with using a single image is that Photomatix needs to be told the EV steps between the created images, as they all have the same exposure setting in the EXIF data, see the screen shot below.
The tone mapping process in Photomatix used the default settings in Detail Enhancer method to produce a realistic output image. There are now visible details where there were shadows, and the sky is slightly darker, or less blown out, with details of the clouds now apparent.
Then the output image file went to a normal photography editing program, Adobe’s Photoshop Elements, where the Auto Smart Fix tool tidied up the exposure and saturation balances and a final touch with the Adjust Sharpness tool and the digital photo is ready.
This sample was not a particularly difficult image to edit, while some HDR efforts seem to be aimed at creating an artistic images, this example shows HDR photo software also can rescue single RAW images where dynamic range poses a problem.
The motion of the thoroughbred racehorses is not a problem as it is in the conventional HDR multiple image capture. The images used for HDR processing in this example are all versions with only exposure variations of the same image, so movement of the subjects is not a problem.
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