James Stephens

Recently I’ve been experimenting with HDRsoft’s tone mapping plugin v1.0.1 for Adobe Photoshop CS2. The plugin is designed to increase detail in shadows and highlights and from what I can see it does a very good job …

Tone mapping

Tone mapping is a technique that is applied to all digital images in the conversion from linear sensor data to that of an image in which tonal information corresponds more closely to the way the human eye perceives brightness. Such a mapping is done globally with pixel-independent settings, typically with a very simple gamma response curve.

Another type of tone mapping operates on an image with more complex, local operators that take into account the pixels surroundings. The mapping takes much longer, but is able to maintain local contrast very well. This local tone mapping technique is commonly used on 32-bit high dynamic range images created from multiple exposures where the application of a local tone mapping process compresses the tonal range down to one which may be viewed. It turns out though that this local tone mapping process is also useful in many instances on single images with detail in the shadows and/or highlights that needs revealing, and this is what HDRsoft’s tone mapping plugin is very useful for.

Note - If you don’t have Adobe Photoshop CS2 don’t worry, HDRsoft has another product, Photomatix, which incorporates all the functionality of the plugin in standalone software, as well as the capability to blend multiple exposures and to generate 32-bit high dynamic range (HDR) images.

Usage

A prerequisite for using the plugin is that the image should be in 16-bit format so you need to shoot RAW (ideally) or to output in Tiff at the least. I don’t recommend converting 8-bit Jpeg files to 16-bit color depth.

Noise levels in the image must also be very low but this is easily fixed with software such as Neat Image beforehand.

From a workflow point of view, the tone mapping plugin may be easily invoked from Photoshop CS2 right after importing the RAW file (and applying any noise reduction that may be necessary).

Here is a screen capture of the plugin’s control screen showing the default settings:

HDRsoft tone mapping plugin settings display
(click image to enlarge)

I generally leave most of the settings at their default values, perhaps adjusting the black and white point settings on occasion. Strength is the most important setting to adjust in order to control exactly how much detail is pulled out of shadows and highlights. This setting defaults to 40%.

Examples

To show you what the plugin can do, here are a couple of example images before/after application of the tone mapping plugin at default settings with a strength of 40%.

Image 1

The detail in this image is very slightly under the limit of the camera’s dynamic range and is exposed so that there is just about no shadow or highlight clipping in the RAW file. Unfortunately, there is a lot of interesting detail in the houses that can’t be seen very well at all.

Before tone mapping
Canon 5D with 24-105 f/4L IS lens @ ISO 200
(click image to enlarge)

Let’s see how the tone mapping plugin does:

After tone mapping
Canon 5D with 24-105 f/4L IS lens @ ISO 200
(click image to enlarge)

The difference is quite startling. A lot of detail has been pulled out of the shadows in the region of the buildings but there is still a good degree of contrast. The sky is pretty much identical and the sand has lightened up a little in a pleasing way.

Remember, this was with default values.

Click on Page 2 below for another example as well as some tips.