Basic Guide to HDR

The photo above was the HDR (High Dynamic Range) sunset photo featured in my last blog post. I have been asked a few times on how to take such a photo, so here is the basic guide on how to take such an HDR photo.

Before we begin, you have to first understand what an HDR photo is. An HDR photo is useful to portray a scene with a very high dynamic range as in the photo above. That means the difference between the brightest and darkest park of the scene is very large, so large that it would not be possible for a digital camera to capture everything correctly exposed. HDR is one way to capture this large range of brightness in one photo.

Making an HDR photo consists of 2 parts, the first part is capturing the scene on the camera, and the second part is processing on a computer.

In general, to make an HDR photo, you need to take 3 consecutive shots of the same scene with different exposure 0, -2  and +2 EV. You will need to go into the camera menu to set “exposure bracketing” with at least +/- 2 EV. You will also need to set the shooting mode to continuous shooting. Please consult your camera user manual if you do not know how to set exposure bracketing. It is different for different cameras, so don’t ask me how to set it for your specific camera.

Now that you have set the camera on exposure bracketing and continuous shooting mode, find a suitable scene with a high dynamic range. Press and hold the shutter release button and the camera should shoot 3 consecutive shots automatically with 3 different exposure. Ideally, you should use a tripod for HDR photos, so that the 3 images would line up perfectly without any ghosting during HDR processing on a computer. However, with new HDR software like “Merge to HDR Pro” in Photoshop CS5, the reduce ghosting feature is so good that it will allow you to shoot HDR photos hand held, unless if you have really shaky hands.

If you have done everything right, you should get the something like the following 3 images.

The first photo is at 0EV, the second one at -2EV and the third one at +2EV. You can see none of them alone can capture the highlight or the shadow together in the same photo.

Now with these 3 photos, you can process them into an HDR photo with HDR software on a computer. There are various HDR software that you can use. Mt preferred choice at the moment is “Convert to HDR Pro” in Photoshop CS5. If you have Photoshop CS 5, it is already included. Here is just a brief outline in what to do.

1. Open Adobe Bridge and select the folder where the 3 photos you want to process into and HDR photo are and then select the 3 photos as shown below.

2. In the menu bar select “Tools/Photoshop/Merge to HDR Pro…”

3. Photoshop would now process and merge the 3 photos. You need to wait awhile, Phtoshop would next bring up a new window with the preview for the HDR photo and various setting you can use to process the HDR photo. There are various prest values you can use. You can experiment on using the various preset as a baseline for further adjustment, but I would suggest “Flat” as a good starting point.

4. Select “Remove ghosts” should help to blend the images properly especially if you were shooting hand held.

5. Next you can play with various settings to try to improve the image. In general, you may have to increase the Exposure and reduce the Highlights. You can also increase the “Detail, but go easy on this setting as too much detail would make the photo looks unnatural. The same goes with Saturation, go easy on it.

6. When you are happy with the setting, press the OK  button and “Merge to HDR Pro” will process and export the resultant HDR photo to Photoshop for further processing.

In general, remember that HDR processing is trying to squeeze a very large dynamic range scene (therefore high contrast) into a photo with relatively low dynamic range. So without further processing, the HDR photo would usually look very low contrast and unnatural. So your aim in Photoshop would be to increase the contrast and help to make the final HDR photo looks natural. The exact step will be different for different photo, and it is out of the scoop of this tutorial. SO play with the setting yourself and find the most ideal result.

Finally, the common mistake in HDR is to go overboard and produce a highly saturated and unnatural looking, and dare I say ugly image. Here is an example……. don’t do it!

 

 

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4 thoughts on “Basic Guide to HDR

  1. Thanks for a wonderful year and all the work you have put into it. When shooting late do you shoot on auto when hand held as all iso values will be different or do you choose a pacific value like 800 or 1200.
    Enjoy your festive break if you get one and best wishes for all in the coming year.

    • Hi Louis,

      Thanks! I hope you and your family are having a wonderful holiday season.

      I usually shoot in Aperture priority mode for HDR and shoot with the lowest ISO possible as noise can be a problem with HDR. I shoot with ISO 100 if possible if the lighting level would not allow hand held HDR shots at ISO 100, then I would turn up ISO to 200 or 400.

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