Processing HDR images
Introduction
An HDR image generated from differently exposed photos can not be viewed properly on standard monitors or on prints. This is because this "raw" HDR image contains a range of values from the deepest shadows to the brightest highlights that exceeds the reproducing capacity of low dynamic range media such as standard monitors.
This is why it is necessary to process the HDR image, mapping its tonal values so that they fit in the limited tonal range of display and printing devices. This way, the details in highlights and shadows stored in the 32-bit HDR image will then become apparent on 8-bit displays. This process is also known as Tone Mapping.
Photomatix Pro provides two methods for tone mapping an HDR image in order to reveal its details in highlights and shadows. One method is called "Details Enhancer", the other "Tone Compressor". The settings detailed below relate to "Details Enhancer".
The HDR processing workflow is as follows:
1. Generate an HDR image, or open a saved HDR image.
2. On the Process menu, click the Tone Mapping item.
To process HDR Tone Mapping as an automated process, please refer to the section Batch Processing.
If you open an HDR image file in the Radiance format and having a size in numbers of pixels higher than a threshold (specified in Preferences and 30 MegaPixels by default), you will be asked whether you would like to open your image in preview mode. If you choose "Yes", which we recommend, you will still be able to get the Tone Mapping window with the preview, but without the Loupe enabled. When you click on Process, you will then be asked the location were you want to save the resulting image. The Tone Mapping will then process the image file at original resolution.
Tone Mapping settings
Strength
Controls the strength of contrast enhancements. A value of 100 gives the maximum increase in both local and global contrast enhancements.
Color Saturation
Controls the saturation of the RGB color channels. The greater the saturation, the more intense the color. The value affects each color channel equally.
Light Smoothing
Controls smoothing of contrast variations throughout the image. A higher value tends to reduce halos and give a more natural look to the resulting image. A lower value tends to increase sharpness.
Luminosity
Controls the compression of the tonal range, which has the effect of adjusting the global luminosity level. Moving the slider to the right has the effect of boosting shadow details and brightening the image. Moving it to the left gives a more natural look to the resulting image.
White Point - Black Point
Both sliders control how the minimum and maximum values of the tone mapped image are set. Moving the sliders to the right increases global contrast. Moving them to the left reduces the clipping at the extremes. The White Point slider sets the value for the maximum of the tone mapped image (pure white or level 255). The Black Point slider sets the value for the minimum of the tone mapped image (pure black or level 0).
Gamma
Adjusts the mid-tone of the tone mapped image, brightening or darkening the image globally.
Color Temperature
Adjusts the color temperature of the tone mapped image relative to the temperature of the HDR source image. Moving the slider to the right gives a "warmer", more yellow-orange colored look. Moving the slider to the left gives a "colder" more bluish look. A value of zero preserves the original color temperature of the HDR source image.
Saturation Highlights
Adjusts the color saturation of the highlights relative to the value set with the Color Saturation slider. Values higher than zero increase the color saturation in the highlights, values lower than zero decrease it.
Saturation Shadows
Adjusts the color saturation of the shadows relative to the value set with the Color Saturation slider. Values higher than zero increase the color saturation in the shadows, values lower than zero decrease it.
Microcontrast
Sets the level of accentuation of local details.
Micro-smoothing
Smoothes out local detail enhancements. This tends to give a "cleaner" look to the resulting image. It also has the effect of reducing low magnitude noise such as noise in the sky for instance.

Important note: The 100% magnification view (displayed when clicking on the preview) may not properly show the effect of this setting when the area magnified is uniform. If you want, for instance, to see the effect of this setting at 100% resolution on a uniform area such as the sky, you will have to select an area that contains an object in the scene in addition to the sky.

Highlights Smoothing
Reduces the contrast enhancements in the highlights. The value of the slider sets how much of the highlights range is affected. This control is useful to prevents white highlights from turning grey, or uniform light blue skies becoming dark blue-grey. It is also useful in helping to reduce halos around objects placed against bright backgrounds.
Shadows Smoothing
Reduces the contrast enhancements in the shadows. The value of the slider sets how much of the shadows range is affected.
Shadows Clipping
Controls the clipping of the shadows. The value of the slider sets how much of the shadows range is clipped. This control is useful to cut out noise in the dark area of a photo taken under low-light situation.
General options
Bit-depth of output image
Sets the bit depth (number of bits per color channel) of the resulting image. Choosing 8-bit compresses the dynamic range down to an 24-bit RGB image that can be saved as a JPEG or 8-bit TIFF file. Choosing 16-bit compresses the dynamic range down to a 48-bit RGB image that can be saved as a 16-bit TIFF file.
The default value is set to 8-bit. You can change the default in the Preferences panel under the Photomatix menu.
360º image
This option is only applicable in the case of Detail Enhancer. It needs to be checked when the image processed is an equirectangular image intended to be viewed as a 360º panorama. Given that Details Enhancer takes into account local contrast, the 360º seams of an equirectangular image will be assigned different tonal values, which will result in a visible seam once the resulting image is rendered in a panorama viewer. Checking this option will correct for this.
This option should only be checked for equirectangular 360º images. Checking it in other cases may produce less optimal results.
Note: Checking this option increases the amount of memory necessary to process the image by about 50%. Processing times will also be increased.
 
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