Landscapes:An introduction to HDR photography
HDR photography is an effective method for successfully capturing a scene where the distance between the shadows and the highlights is very pronounced. Cameras have their limitations, and for some situations, the use of image fusion software to reproduce what our eye has seen is necessary.
The biggest challenge with the HDR photo is to generate as natural an image as possible, without falling into the trap of exaggerated processing that risks breathing a “grungy” and surrealistic look into the finished product. Using simple steps, we will see together how to make an HDR photo to obtain images with bright colors and exciting contrasts.
In this first part, we will approach the notion of HDR photography to understand well its process and the technique to apply to the shooting. In the second part, we will view step by step the various tools to process the final image.
I would like to clarify that each photographer has his approach and that my method is no better than another. I share my experience with you, hoping to give you a guide to invite you to experience HDR photography.
WHAT IS HDR PHOTO?
HDR stands for High Dynamic Range. This technique makes it possible to photograph a scene whose dynamic value is too significant to be captured adequately in a single shot.
Note: Technology has evolved enormously since the first digital cameras appeared. The latest boxes on the market have features that make it easy to succeed in a single image, the dynamic range we are talking about here for the HDR photo. Small downside, the price, they are costly.
HDR from the camera body: Some models offer the possibility to perform HDR from your camera. This is an exciting but limited option. In extreme conditions, such as sunrise, the results will not be satisfactory, the gap between highlights and shadows is too high. Try it for yourself, so you’ll learn to master your camera.
Manual HDR: Using luminance masks, you can take a picture that reproduces the extended dynamic values of the HDR process. Many professional nature photographers make good use of it. However, the complexity of the process is time-consuming and requires the use of software such as Photoshop to merge the different layers manually.
WHEN SHOULD A HDR PHOTO BE TAKEN?
You will use this method on very contrasting landscapes, where the gap between highlights and shadows is very pronounced, sunsets or sunrises are a good example.
If you take a single picture, the details will be lost in the shadows, and the highlights burned, leaving a visually disappointing image. To succeed with this shot, you will need to take three to five photos, sometimes more, at different exposures (-2, -1, 0, +1, +2 Ev) to eventually merge three images to get the full dynamic range of the scene.
Varied dynamic values
To give you an idea of a dynamic value, here are some figures :
- An extreme scene represents: 40 diaphragm
- Human vision adapted to darkness: 27 diaphragm
- Punctual human vision 14 diaphragm
- Digital SLR Camera: 9 f-stop
- Photographic paper: 6 diaphragm
Do the following test: observe a contrasting panorama, stand in front of a building where a bright sun illuminates the background, you will notice that your vision can distinguish details in the shadows as much as in the much lighter parts. Your eye perceives up to 27 diaphragms, that’s why a sunset appears so beautiful to the naked eye, but once on the sensor (which only captures 9 diaphragms), it’s another story! The sky is colorful, but the ground is entirely in the shade.
Low contrast RAW file
Check your histogram: It is not always necessary to take an HDR picture, if your histogram tells you that the scene contains all the appropriate information (a relatively centered histogram), you will get exposure in a single picture.
HOW TO TAKE A HDR PHOTO?
The process for taking an HDR photo can be summarized in three steps:
1. The shooting
You prepare the scene in the same way as if you were taking a regular photo; your camera is installed on a tripod, with the difference that here we will take several images, bracketed at various exposures to merge them later in an HDR processing software.
2. HDR treatment
To merge our series of images, we will use software specialized in HDR photo processing.