Advanced Tone Mapping: HDR

High dynamic range (HDR) is the name for the image that exceeds the brightness range of 256 values (8 bits) per color channel. Commonly used digital technology is historically based on the 8-bit integer formats for data submission and processing which give a very low dynamic range. For example, common standards as JPEG and MPEG allow presenting the range of 1,000:1.

However, often the real scene brightness range is 1,000,000:1 and above. Using HDR allows you to work with the full range of brightness of the scene wiping the historical limitations. High dynamic range image processing has a practical use in creating high contrast scenes, making a low range basing on HDR and giving birth to various artistic effects.

HDR Tone Mapping Algorithms in Photography

One of the most popular image processing algorithms is tone mapping. It is a method of displaying high range colors through colors set of low range to reach maximum similarity with the original image. This method is used in image editing applications. Different applications provide tone mapping tools for various purposes. It is sometimes enough to generate an image that will meet aesthetic expectations of the viewer. In other cases, it is important to reproduce as much details of the original image as possible. Realistic visualization aims to obtain an image of low dynamic range that people will perceive as real scenes from real life.

Naturally, it is impossible to achieve absolute accuracy in the pictures having very high contrast. There will always be some amount of lost data due to the low range of display brightness. Displays that transmit the image of a high dynamic range are difficult to manufacture and sell, because they are too expensive and unpopular. Therefore, we can play with characteristic features of human vision to reduce the loss of detail.

HDR Mapping Variations

In short, tone mapping is the way of condensing a high dynamic range of a 32-bit HDR shot onto a lower range. You can use image editing apps to view, edit and print the pictures. There are many tone mapping algorithms.

They can be divided into two main groups: global and local.

  • Global algorithms are based on the principle of a global contrast. Same mapping is applied to each pixel from high range to low range. Such mapping is based on the characteristics of the entire image. Such algorithms are very fast, but with at a very high range of about 1,000,000 and higher they do not give a satisfactory result. Image details get lost because of the strong range mapping.
  • Local tone mapping algorithms use the principle of local contrast. Image editing software uses additional information about neighborhood of the point it builds up the picture for. As a result, such algorithms provide a better result, but take long time to do the task. Each point requires a separate mapping.
  • Aurora HDR Tone Before:

    Aurora Tone Mapping After:

    User Friendly HDR Tone Presets for Beginners

    It is not necessary to learn all the data above as it gives a general information that you do not always need in everyday life. If you are a beginner, you can start with ready presets in your favorite Aurora HDR on your favorite Mac. Once you feel you can easily manipulate and play with various adjustments, you can proceed to the theoretical part on this page and edit your images manually. All the presets that use tone mapping tools to reach the best results are divided into the following six groups:

  • Basic presets. This category suits for newbies to make first steps in HDR photos editing. There are several variants of colors and tones adjustments to emphasize main details of your image;
  • Landscape presets. It is easy to guess what type of photos we can edit with this variant. I like to play with the clouds by making them look real or as in a fantastic movie;
  • Architecture presets. I love capturing old buildings that represent some historical periods or some specific moments of people’s lives;
  • Indoor presets. It is the most difficult task for me to shoot indoor objects for an HDR image. Tone mapping allows to display all the details of any interior;
  • Dramatic presets. I rarely use this variant as I prefer realistic images, but there are no boundaries for you to express yourself through this option;
  • User’s presets. I have created six presets for editing most of images I take, as I know exactly what I want to see in each of the photo.
  • A marvelous landscape before editing:

    A breath-taking Aurora HDR Lanscape preset:

    Cool Facts about Tone Mapping HDR

    If you have a great experience in photo editing, you are likely to know quite a lot about how it all works. However, there are some issues photographers usually do not pay attention to, as they do not use this information in everyday life.

    1. Tone mapping worsens the qualitative indicators of images while you see a much better photo on your screen.
    2. No matter how high the dynamic range of your image is, you will not be able to see all its glory on your screen. You will have to buy a very expensive display.
    3. Tone mapping is a real magic tool for exposure compensation for both beginners and experts in photography.
    4. You can use tone mapping to turn a single exposure HDR into a masterpiece.
    5. Images editing is not just removing bad areas in the picture, because any person can express any idea in mind through photography.
    6. Tone mapping is the subject to study and test as there is little information who and why can use this feature.

    The Shortest Conclusion Ever

    Photography is a unique phenomenon with a wide variety of paths to go along to reach some specific goals. Tone mapping is one of those paths you can easily go along without stop, as there is always something new to learn. If you are a beginner, make the first step with a single exposure photo and use a reliable app to reach a fantastic result from the beginning. If you are an expert, manual tone mapping tools and a bit of theory will load your fantasy with dozens of ideas. Tone mapping is a remedy for monotonous way of living and boring shots.