HDR Software Review

Auto Exposure Bracketing (AEB) Definition

Kevin — Thu, 29 Apr 2010 15:10:01 +0000

In photography, bracketing is the general technique of taking several shots of the same subject using different or the same camera settings. Bracketing is useful and often recommended in situations that make it difficult to obtain a satisfactory image with a single shot, especially when a small variation in exposure parameters has a comparatively large effect on the resulting image. Auto bracketing is automatic bracketing by using a setting on the camera to take several bracketed shots (in contrast to the photographer altering the settings by hand between each shot).

Without further qualifications, the term bracketing usually refers to exposure bracketing: the photographer chooses to take one picture at a given exposure, one or two brighter, and one or two darker, in order to select the most satisfactory image. Many professional and advanced amateur cameras, including digital cameras, can automatically shoot a bracketed series of pictures, while even the cheaper ones have a less convenient but still effective manual exposure compensation control.

— End of Auto Exposure Backeting Definition —

Digital Cameras You Need for HDR Photography

Kevin — Thu, 29 Apr 2010 14:48:34 +0000

HDR Sofware works with differently exposed photos. To get good results, it is important that each one of the source photos are taken with a sufficiently different exposure in order to properly cover the dynamic range of the scene. Taking three photos separated by two EVs (i.e. two full-stops), or five photos separated by one EV, will be sufficient for most outdoors scenes.

Many digital cameras include an Auto Exposure Bracketing function that makes the process of taking several exposures easier and faster. If you select Aperture Priority and then use Auto Exposure Bracketing, the camera will automatically take 3 or more shots at different exposure times when you press the shutter release button.

A camera offering the Auto Exposure Bracketing option is therefore recommended for taking HDR pictures. However, this option won’t be useful if the maximum EV step possible with Auto Exposure Bracketing is less than one EV for your camera. If your camera offers less than that (for instance 0.7 or 2/3 EV), then Auto Exposure Bracketing won’t be useful and you will have to change the exposure times manually.

A list of camera models with their AEB settings is available here.

A two-EV spacing is best for capturing images intended for HDR. However, a one-EV spacing is still OK if the camera can take 5 or more frames with Auto Exposure Bracketing.

Global Tone Mapping and Local Tone Mapping, the Difference

Kevin — Mon, 26 Apr 2010 15:29:57 +0000

What’s the difference between global tone mapping and local tone mapping?

Global tone mapping technologies refer to techniques that use a monotonic mapping curve to independently transfer real-world lighting and color to your display. These technologies are relatively simple and fast. However, these technologies cannot give impressive results.

In comparison, Local tone mapping technologies consider pixel neighborhood information in the mapping processing for each individual pixel, which simulates the adaptive and local property of human vision system. Thus, Local tone mapping technologies can achieve much better results. However, this will take longer for your computer to process.

In HDR software, global tone mapping technologies are usually used for fast preview of images, while local tone mapping technologies are used to prepare the final results for display or printing.

Tone Mapping, the Definition

Kevin — Sun, 25 Apr 2010 04:29:18 +0000

What is Tone Mapping?

Tone Mapping is the technology used to convert 32-bit float pointing format to 8-bit images for display or print, which captures our visual experience in the process of conversion. Since 32-bit float pointing radiance map is also called digital HDR negative, Tone Mapping can be regarded as the corresponding development process of the conventional photography workflow.

Tone Mapping is the most important part of the HDR software, therefore, in order to determine whether a HDR software is good you must first look at the quality of the Tone Mapping. You can see a full comparison chart of HDR software here.

Why Need Tone Mapping?

Usually, the first step of HDR software is to merge photos with different exposures into a 32-bit float pointing radiance map, which is also called a digital HDR negative. Compared with a conventional 8-bit image format like JPEG, BMP, 32-bit float pointing format has a much wider range to record any small or large values and thus can accurately record the full dynamic range of the real world. However, 32-bit float pointing value cannot be displayed or printed in current 8-bit monitors or printer. To users they are just meaningless numerical numbers no matter how accurate they are.

—End of Tone Mapping Definition—

Photomatix System Requirements

Kevin — Sat, 24 Apr 2010 09:30:21 +0000

What are the system requirements for Photomatix?

On both platforms:

1 GB of RAM (more recommended, the more the better)
500 MB of available hard-disk space (more recommended)
1,024×768 or greater monitor resolution
Color monitor with 16-bit color or greater video card

Windows platform:

Photomatix Pro: Windows Vista and Windows 7, or Windows 98, ME, 2000 or XP with .NET 1.1 framework or higher (if the .NET framework is not installed, the installation wizard of Photomatix Pro will invite you to download it from Microsoft’s website).
Photomatix Light: Windows Vista and Windows 7, or Windows XP with .NET 2.0 framework or higher (if the .NET framework is not installed, the installation wizard of Photomatix Pro will invite you to download it from Microsoft’s website).

Mac OS X platform:

Photomatix Pro: Mac OS 10.3.9 or higher – Photomatix Light: Mac OS 10.5/10.6
G3, G4, G5 or Intel processor