Exposure Fusion Vs Tone Mapping In Photomatix

By YPHDR, Tutorials

If you’re a Photomatix user like me.

The chances are:

You’ve been tone mapping all the time without realizing there’s actually another option.

 

Discover Exposure Fusion

While tone mapping creates eye-catching images, exposure fusion is capable of producing more eye soothing HDR.

“What is exposure fusion?”

“How is it different?”

I’ll explain the differences between the 2 and give you an example so you can make a judgement yourself.




Tone Mapping

Probably THE most popular way of processing an HDR image (check out these 20 amazing examples of HDRI).

To really understand the differences between the 2, let’s look at how it works.

First Step: Creating A 32-bit HDR Image

As we all know:

Tone mapping maps the color of a set of pixels to another to approximate the appearance of a high dynamic range image.

When you merge multiple exposure in Photomatix, it creates a 32-bit image – a true high dynamic range image that can’t be displayed on our monitor (yet).

32 bit hdr image
An unprocessed 32-bit HDR image

That’s why the 32-bit image always looks over or underexposed.

One method to render a 32-bit image to be displayed on our monitor is through tone mapping.

 

Interesting fact:

Just a few years back, Photoshop and Lightroom can’t process 32-bit images.

So most photographers rely on HDR software to scale the pixels to a low dynamic range image that shows the tonal details of the entire dynamic range.

With the current version of the software, you can apply tonal and colour adjustments to a 32-bit image with the controls in the adjustments panel, giving you another option to process 32-bit HDR.

Find out more about creating natural 32-bit HDR in Lightroom here.

Next: Tone Mapping Is A 2 Step Process In Photomatix

Global mapping and local mapping.

According to HDRsoft (company that creates Photomatix):

Global mapping maps the brightness value of a pixel in the final image based on its brightness value in the original image, as well as global image characteristics, but not on the pixel’s spatial location.

This means a pixel’s brightness is dependent on its original brightness and the brightness around that pixel. It doesn’t take into account where the pixel is located.

On the other hand…

Local mapping maps the brightness value of a pixel based on whether the pixel is located in a dark or bright area in the original image.

This means as opposed to global mapping, local mapping takes into account where the pixel is located on the image.

tone mapping
HDR image processed with tone mapping

 

Tone Mapping In A Nutshell

In the adjustments panel in Photomatix:

Tone Compressor = global mapping.

Detail enhancer and Contrast Optimizer = local mapping.

I hope I haven’t confused you even more!

 

Exposure Fusion

Exposure fusion, on the other hand, is much easier to understand.

As the name implies:

It merges (or fuses) different exposure into one single file.

You’re probably thinking:

“Isn’t that how tone mapping works?”

It’s similar, but…

The highlight details are taken from the darker exposure and the shadows details are taken from the brighter exposure.

A concept that is similar to exposure blending, and the advantage?

 

Less image noise!

Puzzled?

So, the final image processed with exposure fusion is a weighted average of the source files.

What’s more?

Compared to tone mapping, exposure fusion has fewer adjustments to play around.

This doesn’t mean exposure fusion is not as good as tone mapping.

Sometimes less is more.

exposure fusion
HDR image processed with exposure fusion

 

Which Is The Best?

Everybody wants the best.

But is “the best” always the best for a given image?

Which method is supposedly the best to create HDR image?

Or should I re-phrase the question:

What style of HDR do you like?

 

Before = tone mapping; After = exposure fusion.

 

Show Off Your Creativity With Tone Mapping

Tone mapping has more adjustments available to tweak and fine tune your image.

As the result…

You can create striking HDR images that often attract immediate attention in the photography community.

But its strength is also its weakness.

Any image noise present in the source file will be exaggerated.

Do it right and you’ll earn the respect from the HDR elders.

Gone overboard:

…and your image may end up here.

 

Comparing image noise. Before = exposure fusion; After = tone mapping.

 

Stay Natural With Exposure Fusion

If you’re not into the classic HDR look, then maybe this is for you.

Exposure fusion allows you to create ultra natural HDR image.

Plus…

It reduces image noise (which is really a bonus!) and doesn’t have as many adjustments to overwhelm the beginner.

The drawback?

The final image may look a little flat compared to a tone mapped image because you can’t adjust micro and local contrast.




Conclusion

Both tone mapping and exposure fusion are good ways to creating HDR images.

Tone mapping allows you to let your imagination and creativity run wild.

But if you prefer a more conservative approach, exposure fusion is the method of choice for you.

 

Learn More