Exposure Blending
Introduction
Photomatix lets you combine images with different exposures using the Average method or one of the Highlights & Shadows methods. Those latter methods perform a process known as Exposure Blending
The Highlights & Shadows methods make use of advanced algorithms to select and blend together the details available in the different exposures.
The Average method combines the images using the same average formula everywhere, regardless of whether the computed pixels are in a dark or bright area. This is why averaging can not produce the dynamic range extension that you can get with one of the Highlights & Shadows Exposure Blending methods. However, averaging has the effect of reducing noise and is often used for a process called Image Stacking.
To use the Exposure Blending functions of Photomatix Pro:
1. | Open the images taken under different exposures.
2. | On the Combine menu, click one of the Highlights & Shadows item. For help on choosing an item, see Which one of the "Highlights & Shadows" combination methods should I use? under the FAQ section of our Web site.
3. | The window lists the source images (see note below) that will be combined into one image with details in highlights and shadows. If the images are not aligned (e.g. shot without the aid of a tripod), check the option Align images.
4. | Save the result.
Additional adjustments in the case of method Highlights & Shadows - Adjust are described here.
To blend exposures automatically and/or process large files, please refer to the section Batch Processing.

Notes:
Source images
- | All image files that you have opened, excepted images in Radiance RGBE format, are considered source images. source images should be images of the same scene taken under different exposure settings. Once you have combined source images or applied tone mapping to an HDR image, the resulting images are not considered source images. This way, you can easily compare the results of different combination methods by running them successively on the same source images without having to close the window showing the previous result.
- | If the source images do not have the same size, the resulting image is computed based on the size of the smallest source image.
- | To function properly, the combination requires that the source images are perfectly aligned. Even though Photomatix provides automatic and semi-manual/advanced alignment tools, it is recommended to use a tripod when shooting the different exposures. A tripod is less necessary if your digital camera has an automatic bracketing function and you make sure that the camera does not move during shooting.
Processing times
- | Processing times depend on the size, bit-depth and number of source images, as well as the combination method and the method's settings (in the case of "H&S - Adjust" and "H&S Intensive"). For the size of the images, what matters is the size expressed in number of pixels (width x height). Compressing TIFF images as JPEG will not reduce processing times unless the height and/or width are also reduced.
- | Estimated processing times are approximate. Processing times are also influenced by the number of other memory-hungry applications on your computer that are running at the same time as Photomatix.

| Help Content | Photomatix website