1. HDR Photography
Hishamuddin Siri

2. Aims of this tutorial
The main aim of this tutorial is to help people use HDR techniques to produce photos with a higher dynamic range than they normally get in a standard out of the camera photo. I will show you how to take a shot from the one on the left, to the one on the right.

3. What is HDR?
HDR means ‘High Dynamic Range’. Using software like Photomatix you can create images with a more detail in the highlights and shadows than you can with a normal photo from todays digital cameras. Its similar to the old technique of exposure blending. Taking one photo for the sky and one for the ground, then merging them both together in Photoshop.
HDR takes it a step further by increase the amount of detail in the image and allows you to create some unique photos. You can use it carefully to create natural looking photos or you can use it creatively to create atmospheric and emotive photos. The choice is yours as to how you process the end result

4. Tools Needed ;
A RAW editor such as Aperture, RawShooter, or Photoshop. Secondly, the HDR program.  Photomatix.

5. Step 1: Source images
There are two main ways to create the source images needed for HDR. You can either use AEB, auto exposure bracketing, on your camera to take 3 images while you are out, or you can use RAW to take 1 image and then use a RAW editor to produce 3 shots back at your computer.

6. Auto Exposure Bracketing (AEB)
The main advantage with AEB is that you can get better source images with less noise. For example, a sunset. You would normally get really dark shadows and enhancing them later from 1 single RAW file would increase the noise. With AEB you can take a completely seperate image for the shadows and one for the highlights to preseve the detail and keep the noise to a minimum. The disadvantge to this approach is that anything moving in the image will become blurred and repeated as it moves across the 3 images. To start with you will need a camera that has the AEB mode and a tripod. You will also need a tripod so that the 3 shots you take can be perfectly aligned later. Go to the menu on your camera and set the AEB mode to -2 / +2 stops.

7. Canon System
It should look like the right image after the changes. Compose your shot, and set the camera up as your normally would to take a picture. Now after you take a picture you will see the exposure compensation level drop down to -2. Take another picture and you will see it goes up to +2. You will notice the shutter speed or aperture changes too. This allows you to get the three shots for the shadows, a balanced image and for the highlights. You now have the 3 shots required to produce a HDR image.

8. Using A RAW editor
The other way to produce the 3 shots needed is to take 1 photo and adjust in a RAW editor such as Aperture, Photoshop or RawShooter. The main advantage to this is that you can produce a HDR shot with moving subjects such as people or cars. The disadvantage is that if you use an image with very dark shadows and you’re trying to boost the exposure, the result will be quite noisey.
Load your photo into the editor, then set the exposure level to -2 and save the image as a 16bit TIFF without any metadata such as EXIF info. This is the important part. If you save it with EXIF info you will find that Photomatix relies on that info to produce the HDR shot. The problem with this is that the shutter speed and aperture values will be the same across the 3 images and Photomatix won’t know which image is -2, 0 and +2. Set the exposure level to 0, save that and then set it to +2 and save that image.

9. This is how it looks in Aperture
This is how it looks in Aperture. You will now have the 3 images needed to produce a HDR image.

10. Step 2: Generating a HDR image
Open the 3 images into Photomatix. From the HDRI menu select Generate HDR. Photomatix will ask you if you want to use the 3 opened images or load in some. Make sure it has “Use opened images” selected and click ok.
Now Photomatix will confirm the exposures for each image. 9 out of 10 times it will get it right, but just incase make sure that each image has the correct exposure settings. In the case of this guide they should be +2, 0, -2.
Click ok, then check that “use standard response curve” is selected. If you are using 3 images taken at the scene tick the “Align LDR images before generating HDR image” option just so that Photomatix aligns the images for you. Click ok and after a few minutes you will see your HDR image. It won’t look exactly right just yet. Some areas will be slightly over-exposed and it’ll look odd.

11. Step 3: Tone Mapping
This is the magic part. Using the Tone Mapping feature in Photomatix will convert your HDR image into something usable. Goto the HDRI menu and select Tone Mapping. You will see how your photo looks more like a standard HDR image. The sky will be nicely exposed, as will the ground. The trick now is to adjust the settings to get a nice balanced image. You could be creative and go for something a little more fun if you feel like it. For the image in this guide I wanted something special and yet not too far from the real world. I’ll start with a quick run down of the various options.

12. Luminosity
Adjusts the brightness of the shadows. Moving the slider to the right has the effect of boosting shadow details and brightening the image. Moving it to the left gives a more natural look to the tone mapped image. The optimal value depends on the image and the effect you want to achieve.
Strength Controls the strength of local contrast enhancements. A value of 100% gives the maximum increase in local contrast. The optimal value depends on the image and the effect you want to achieve.
Color Saturation
Controls the saturation of the RGB color channels. The greater the saturation, the more intense the color. The value affects each color channel equally.

13. White Clip – Black Clip From watching the way the histogram changes, the white clip adjusts the highlight contrast and the black clip adjusts the shadow contrast.
Micro-smoothing: Basically this setting should be called “How arty do you want your shot?” At 0 you can get the cool arty style HDR images with all the detail in everything from walls to clouds you didn’t know where there. However, if you want a nice simple blended exposure photo set it to % of the image should be perfectly exposed as if you spent hours putting them together in Photoshop. This is a great new addition to Photomatix as it allows people to use the software as they see fit. If they want a nice photo that is perfectly exposed then they can get that just as if they used ND Gradient filters on their lens. However, if like me they want something a bit more unique they can drop the micro-smoothing down and get something dramatic.

14. Light smoothing: Never set this below 0 as you will get horrible results.
Microcontrast Controls the accentuation of local details. The default value (High) is the optimal value in most cases. However, this control may be useful in the case of a noisy image or when the accentuation of local details is not desirable (e.g. seams of a stitched pano in a uniform area may become visible when local details are too much enhanc

15. Real World Examples Settings used;
Luminosity +8, Strength 25%, Colour Saturation 65%, White Clip 0.220, Black Clip 0.075

16. Natural Feel 2

17. Sample HDR Photo