What is Tone Mapping and How to Create a Stunning HDR Photo
Last Updated on April 2, 2023 by Peter Wood
It is important to understand what tone mapping is since it is the basis for most image adjustments, although you don’t realize it at all. It is said that the photos are all about luminance and color. That is absolutely right and Tone Mapping makes luminance and color adjustment easy on different displays. In another word, it takes a key role to display the right RGB values on different monitors.
Tone Mapping is used to change the tonal values of pixels in an image so that they are remapped consistently to new values. When you want to apply tone-mapping effects, HDR photo editors are the excellent choices you have to consider. Learn more knowledge about this concept and how to apply it.
Part 1: What is Tone Mapping HDR
Before learning Tone Mapping, you should understand some key concepts. An image is comprised of pixels no matter you took it with a digital camera or smartphone. Each pixel has a color, including black and white. To define these colors, which usually use RGB system, such as 255, 0, 0. The three values tell the amount of red, green and blue to produce the color for a pixel. This system is also known as the color channels in photo editors.
Of course, the RGB system is just one representation of color to help you understand Tone Mapping. In some photo editors, it may be presented as a map. In Photoshop, for example, Tone Mapping shows in curves.
According to meta-data, Tone mapping adapts digital signals to appropriate light levels. This process is not simply applying the Electro-Optical Transfer Function to an image but try to use the metadata information to map the image data.
When it comes to creating an HDR image, you take a range of brightness that is beyond what a standard 16-bit digital camera can capture, such as 32-bit. But such a file cannot be displayed on conventional display equipment. In such cases, it requires the process to turn this into an image file that can be displayed. That is where Tone Mapping comes in.
On the other hand, there are wide ranges of display devices available on market today. Each of them has its own luminance and color range. That makes correct tone mapping necessary for an excellent viewing experience.
Part 2: 2 Methods of Tone Mapping HDR
Generally speaking, there are two types of Tone Mapping algorithms:
Local Operators
Local operators take note of the position of a pixel in the light or dark areas for each image. Then pixels are treated based on their spatial characteristics and details are eked out of them as a result. Therefore, the image becomes more accessible to our eye and has more details. The downside is that it takes a longer time to process.
To implement a local Tone Mapping algorithm, the steps are as follow:
- Input is the RGB value of radiance.
- Compute the intensity.
- Compute the chrominance channels.
- Compute the log of the intensity.
- Apply bilateral filter.
- Compute the detail layer.
- Apply an offset and a scale to the base.
- Reconstruct the log intensity.
- Put the colors back.
- Apply gamma compression.
Global Operators
For global operators, each pixel is mapped according to global characteristics, regardless of where in the image it falls. It means that the pixels in the light or dark portion will be ignored. Compared to local operators, this method is fast. However, the cost is a flat image.
Part 3: Tone Mapping Tips for Shooting and Editing
Tone Mapping Tips for Shooting
- Shoot a flat image. No matter editing the photo later or not, you should produce a flat image with as much detail as possible. The adjustments of Tone Mapping will be done in your photo editor.
- Control color. Tone Mapping is all about color as mentioned above, although you can manage it in your photo editor.
- Process artifacts beforehand. Similar to color control, photo editors vary in how to deal with artifacts, like noise. You’d better learn your tools and retouch your photos.
- Expand the dynamic range by making an extra exposure. It is well known that you need to take more than more exposure when producing an HDR image. So does HDR Tone Mapping.
- Keep the gap between exposures small.
Tone Mapping Tips for Editing
- Never use the presets as your final tone mapping decision. Most photo editor software provides presets to help you simplify the Tone Mapping process. But they are not as customized according to your requirement. The best solution is to apply a preset and adjust the options manually.
- Save your Tone Mapping settings. A preset won’t work the same from project to project since the dynamic range will vary from one scene to the other. But you can use them as the starting points for other projects and do fewer adjustments.
- There are always ways to recover your HDR projects. Tone Mapping is the key. When you get weird-looking skies that have electric blue patches, for example, reduce the white point. That will decrease the overall HDR effect in your final work.
- Keep saturation below 65 percent when editing tone-mapping HDR.
- Use two or more photo editor software to polish your Tone Mapped images.
Part 4: How to Apply Tone Mapping HDR
How to take advantage of the tone mapping effects to create some stunning HDR photos? WidsMob HDR is a versatile HDR photo editor to stitch HDR photos with tone mapping, ghost suppression, and auto-alignment. It also enables you to apply multiple HDR effects and adjust the advanced HDR parameters, including smart tone mapping color enhancement, color correction, contrast enhancement, highlights, and shadows. Moreover, you can also tweak the image radiance, vignette, and HDR de-noise to make stunning HDR photos.
- Provide the auto tone-mapping algorithm to stitch bracketed images into an HDR.
- Tweak the different tone mapping effects to touch up the details of HDR photos.
- Apply some fake tone-mapping filters to some single photos with HDR effects.
- Support JPEG, JPG, PNG, TIFF, and RAW file formats for most cameras.
Step 1: Once you have installed WidsMob HDR, you can launch the program on your computer and click the Add Photos icon to import the bracketed images. Moreover, you can also add single photos to apply the desired tone-mapping effect directly with multiple file formats.
Step 2: Select the tone mapping method as the Bracketing mode, which enables you to stitch the bracketed images into a standard HDR. It will auto-align the photos with optimal tone mapping and ghost suppression. Of course, you can choose the Single Photo mode to apply HDR filters.
Step 3: Just choose the desired HDR effect from the Effect tab or go to the Advanced tab to further adjust the smart tone. Just use Color Enhancement, Color Correction, and Contrast Enhancement under the HDR menu, or Highlights and Shadows under the Smart Tone menu to adjust the tone-mapping effect.
Part 5: FAQs about Tone Mapping HDR
As the post-processing technique, tone compression sets the correct tone across the image. This process in HDR photography produces a base image, from which you can make other edits. It will apply more saturation for the tone compression for the bright image to add more realistic.
Go to the Settings app, you can tap on the Camera icon and enable the Auto HDR option. After that, you can turn back to the Camera app to find the HDR option at the top of the screen. After that, you can take photos with iPhone camera with tone mapping effects.
Even the best digital camera will only see in one dynamic range. Camera sensors are improving, but they won’t see what the eyes can see. HDR photography works to emulate what you see with your eye. It does this by merging more than one photo. These photos will have different exposure levels.
Conclusion
Based on the sharing above, you should understand what Tone Mapping is when you need to learn the filter, and more. It is involved two sides, your images and the device that your images display. To get the perfect viewing experience, Tone Mapping is a necessary technique. It allows you to adjust the luminance and color of each image before displaying it on the target device so that you can get the best presentation. If you need to apply the optimal tone mapping for both bracketed images or single photos, WidsMob HDR should be the desired choice.