Photoshop Tutorial: HDR

Published August 15th, 2006 in: Photoshop

As a new DSLR camera owner it didn't take long before I stumbled upon the term HDR, short for High Dynamic Range. In this Photoshop tutorial you will learn how easy it is to produce your own HDR images!

[Click here to see a larger image]

HDR vs LDR

HDR images are images with a wider dynamic range than what is possible to view on computer screens and other digital equipment limited to 8 bit RGB. When working with 32 Bits HDR images in Photoshop, you have full access to this higher dynamic range, making it possible to fine tune the exposure and compress the image down to a lower bit-range. This way, withe the help of Photoshop, we can pick up the best parts of several exposures, and merge them to an optimized version of the sceene. This HDR image can them be downsampled to a normal 8 Bit image.

The 8 Bit Problem

Working with RGB equipment means working at 8 bits per channel (256 values of each color red, green and blue), which gives us a very Low Dynamic Range.

Here's what you typicaly end up with, shooting a nice sunset on a DSLR and viewing it in Photoshop: To be able to see the sky you'll need to under expose, and this will make the landscape too dark.

Merging Multiple Exposures

To make a HDR image in Photoshop, you will typically merge 3 or more exposures of the same scene, shot from a tripod. The different exposures should contain all the deepest shadows to the brightest highlights of the scene. Obviously, to get the details of a bright sky, the landscape will be too dark - and to get a detailed bright landscape, the sky will be way too bright. But like this tutorial will show you, this is what combined will produce a HDR image.

How to work with HDR in Photoshop CS2

1. Import Source Files to Photoshop

Ok, so lets start the tutorial. First, in Photoshop CS2 you will find the magic pathway under 'File>Automate>Merge to HDR...'. Here you'll first select the different exposures you want to use for your HDR, and optionaly if you want Photoshop to automatically align them. It's best to shoot source images on a tripod, or else the HDR image can get somewhat distorted. Shooting from a tripod you should be able to skip this option.

2. Set White Point Preview

This step is basically a preview step. Photoshop gives you the option to deselct/select which source images you want to keep, and then preview the White Point result. It doesn't matter where you set your White Point, but as it will set the working space for the merged HDR image, you should set it to where you can see a decent preview of your image. When done, press OK, and Photoshop will give you a merged 32 Bits HDR image.

3. 32 Bits HDR Image

Here is the 32 bits HDR image produced by Photoshop. Yes, it still looks kind of dull, but remember - it contains a higher dynamic range than the computer screen can produce. So this image is really a super starting point for the tweaking ahead. First, we save it as an openEXR or TIFF for backup purposes.

4. Down to 16 Bits

Now, to be able to do something with your HDR image in Photoshop, you have to change it to 16 Bits (if you use other software, like Adobe After Effects 7, you can continue to work in 32 Bits).

5. The difficult conversion step

After you select 16 Bits, you'll get the 'HDR Conversion' panel up. Select the 'Local Adaptation' method and start experimenting with the Toning Curve and Histogram functions. This part can be very difficult to get to grips with, but this is where you decide which exposed parts you want to emphasize in your HDR image. A tip is to use a high radius on larger images.

6. Adjusting Exposure

You can skip this. Some images need it, some don't. However, if you do see obvious exposure problems, then this is the right time to fix it.

7. Adjusting Color Balance

And this is where it will happen. Working with Color Balance in Photoshop will produce the most dramatic changes to your HDR image. Do Highlights first, then Shadows and Midtones last. I often find that I get interesting results when I tweak Highlight and Shadows to opposite values. Turn off 'Preserve Luminosity' as this will give you less contrast problems.

8. Final Result

The final step is to crop the image and bring it down to 8 Bits, and you are done!

Creating Your Own HDR Images

That's it for this HDR Photoshop Tutorial, and I hope you found it usefull. I'll be writing more HDR tutorials later, covering other aspects of how to produce good results in Photoshop. Last, if you want to have a go at it yourself, you can download three of the original shots here: photoshop_hdr.zip [5.94 MB]

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