HDR Photography

I had the privilege to be invited to speak at the London Camera Club and the topic they asked me to speak about was HDR photography. We had an enjoyable evening and there was lots of discussion about this interesting subject. The next morning I received a series of emails from different club members who had some questions about the different steps of the process and the software I demonstrated. So I have put down in note form the presentation, and at the bottom of this article there is a video that you can click on to view the process of assembling your images.

Thanks again for the invite and all the emails.

James

HDR Photography

HDR photography is an interesting way to create an image of a high contrast scene, that you know will blow out your highlights and make your shadows appear flat or lifeless, and make it come back to life correctly exposing for all areas of your photograph. This is achieved by taking a series of images 2 stops apart, normal over and under and combining them with computer software like Photomatix or Adobe Photoshop to reveal the best of each exposure. I will be using Photomatix to assemble my series of images.

HDR which stands for High Dynamic Range, by definition enables photographers to record a greater range of tonal detail then you could ever capture in a single exposure. This sets digital photography apart from film photography as this is something that was not possible.

In this article we will walk through the steps of capturing the series of images, a few photo tips on how to improve when shooting for HDR and then the post processing process in your computer.

Preparing for your shoot:

First of all in creating an HDR image, a few things that are handy to have on hand, a sturdy tripod, a camera remote trigger, or cable release and a little patience. Most camera manufacturers offer the ability for the photographer to set his or her camera to allow auto bracketing, you will need to consult your instruction manual for you specific camera to find the settings.

For best results you should also set your camera to capture the images in RAW mode, as this will allow better colour space, jpeg files will work but they only reflect a 256 colour base thus limiting the colour space of your end result.

Capturing your images:

When setting up your shot, you want to make sure you change your exposure via your shutter speed and not your aperture. If you adjust your aperture for your different exposures you will affect your depth of field and have difficulty in creating a sharp image. A good suggestion for a starting point for camera settings is an aperture of F16 and an ISO setting of 200. You composition should consist of three to seven images, and your exposure value should be at least 2 stops apart. Think of it this way if you increase the amount of shots and exposure values you are filling in extra exposure space and therefore should improve the quality of your end result.

After you have composed your image, set your camera on manual select f16 for your aperture balance your exposure and take your correct exposure, then increase your shutter by two stops make your next exposure, then go back to your correct exposure value and decrease your shutter by two stops below that and make your third shot. You have now capture the images required to build your HDR image. As I said in the begging of the article some cameras allow you to do this automatically, select the auto EV on your camera menu, then set your camera for aperture priority select f16 and the camera will make your selected amount of exposures.

One tip to consider when capturing HDR shots, especially if you are making numerous exposures, it to put you hand in front of the lens prior to shooting your first image and do it again when completing your final image. This will easily help you when sorting your files once you have loaded them into your computer.

Post Processing your Images in your Computer:

Once you have uploaded your images into your computer, you are ready to start creating the HDR image. We will look at using software called Photomatix to complete the process.

**a note about Photomatix you can download a trial version of the software at no charge from www.hdrsoft.com, and use it as much as you wish, but when you save the image it will leave their company watermark on the image. You will have to purchase the software to remove the watermark but this will allow you to experiment with the program and how it works. In all my research so far using this piece of software is one of the easiest ways to create an HDR image.

Here are seven images we will assemble.

Step One: Open Photomatix program and click on “Generate HDR image” this will open a dialogue box that will ask you to select the images you wish to use to create your HDR shot.

Step Two: Once you have selected your images, click ok, and the next box that opens will ask you a few questions on how you want the software to process the images. You can leave it at the default settings or have the option to change a few items. For instance you can ask the software in Align source images you can ask it to correct horizontal and vertical shifts. You can click on reduce noise if shot in extreme low light and you are getting excess amounts of digital noise in your image. By clicking Attempt to reduce ghosting artifact, this will help correct movement from water or foliage, there is even an option for Moving objects/people. Finally White Balance, I generally leave this setting As Shot, and adjust at the end of the process. Now click Generate HDR.

Step Three: Once your image has been generated you will see that looks a little strange, don’t be discouraged, you are looking at a 32bit image, and your computer screen can not represent the full spectrum of the image. But as you can see from the example below you can move your mouse around the image to check the results and see it in the navigator window. Here you see the trees are going to appear in your final result even though they appear black in the image you see in this step. Now click the tone map button.

You can make numerous adjustments to your image, at this stage, allowing for higher contrast, colour saturation, etc. I would suggest to leave things were they are for a start and then as you become more experienced with the software reassemble your image in steps one through three and make adjustments.

Now click on the process button.

There you go, you have just created your first HDR Image, you can now save it as a TIFF or a jpeg and take it into Photoshop for any final adjustments or cropping.

Here is an image of the final result.