HDR in Melaka Explained

Posted: 30th September 2008 by Jacky Yong in Computers, Photography
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I’m bored. Melaka is a place that I go to almost every time I go back to Sagil. Photographically speaking, I have also taken almost everything there is to be taken in Melaka. So I have decided to do something really drastic.

High Dynamic Range imaging, or HDR as it is commonly known, is a very exciting process where you can expect to see images with a very wide range of exposure information, commonly from direct sunlit areas of the cloud to the shadowy areas under the tree, in one picture. Imagine this scenario. You are taking a picture of a building. Unfortunately the sun is directly behind the building. Chances are, your picture is likely to get either over or under-exposed, depending on where you are pointing your camera at that time.

Shot taken in RAW and tweaked to bring out the details in the cathederal. If taken under JPEG, I doubt this image will turn out well.

Shot taken in RAW and tweaked to bring out the details in the cathedral in Singapore. If taken under JPEG, I doubt this image will turn out well.

If you have a camera that is capable of storing the images in RAW (not necessarily a DSLR, and there are plenty from Panasonic and Fuji), you may even push the range a little higher by processing in the computer. But nothing beats a proper multiple-exposure HDR.

What is a multiple-exposure HDR?

This is HDR image generated from more than 1 pictures of the same scene in multiple exposure settings. In a DSLR, this is easily achievable using exposure bracketing. This is different from camera to camera, but on my 350D, it takes three shots in a consecutive burst. One with -2.0 EV, one with 0 EV, and another with +2.0 EV. In layman term, it means it will take one picture with normal exposure, one which is darker, and one which is brighter.

Balanced Exposure Shot

Balanced Exposure Shot

Over Exposed Shot. Notice that there are more details in the wheel area

Under Exposed Shot

Under Exposed Shot. Notice that there are more details in the sky and the wind screen

As you can see, there are effectively 3 different pictures. If you scrutinize the picture properly, you may notice that the pictures are not really identical. When I took the pictures, my hand could have moved a little, skewing the composition a little. The best way to take these kind of pictures is to use a tripod, or at least resting on a stable surface. Nevertheless, using hand is still possible. You can merge the pictures together later using proper software. I’ll come to that later. For me, the Image Stabilizer on my 17-55 do a great job in giving me a proper jerk-free images. In any case, I am taking mostly landscape photos, which requires minimum focal length. That translates to relatively stable hand movement anyway. Even with the Image Stabilizer turned off, I am confident of getting shake free pictures.

The trick is in the software

Next up is where the magic is weaved; the computer. Or more specifically, the software to process the photos. By now you may be wondering why is the two seemingly spoilt pictures be any useful at all. There is in fact plenty of information that can be gathered from these over- and under-exposed shots. The under-exposed shots will reveal more details in the clouds, while the over-exposed shots will reveal more information in the shadowy areas without noise turning up.

My workflow consists of two main softwares. The first is the Merge HDR function found in Adobe Photoshop CS3. It’s under File – Automate – Merge to HDR. Specify the 3 RAW files to be merged. Don’t worry if the pictures are not aligned. Photoshop is smart enough to merge the photos seamlessly and crop the excess area.

The 3 pictures, miraculously merged together!

The 3 pictures, miraculously merged together!

You will see a merged photo. At this point, the photo does not look like much. Do not worry, click OK in the screen above. The white point below the histogram will not affect the final output, as we’ll see later. Save this picture as a Radiance format, or .HDR file extension. This Radiance format is a 32-bit file that contains a very high range of information, from the lightest of the clouds to the darkest of the shadows. Your normal computer monitor will not be able to display them all in one place. For your info, a normal JPEG picture only contains 8 bit of info per pixel.

Save as Radiance format. Cool name eh?

Save as Radiance format. Cool name eh?

The second piece of software I’d like to explain in my next workflow is Photomatix. It’s a really cool piece of software that can read the 32-bit file and “compress” the range of highlights and shadows into regions that can be displayed to the monitor screen and the human eyes. They term this as Tone Mapping. This has an interesting side effect. It makes the picture more surreal in areas where the image would not normally be seen by the human eye. Normally an HDR image will have its contrast and saturation bumped up to really give depth to the picture.

You can tweak for contrast and saturation here

You can tweak for contrast and saturation here

Here in Photomatix, adjust the values for Strength (the contrast) and Color Saturation. The Luminosity lets you find the best exposure for the dark areas while Light Smoothing gives a sort of mysterious aura to the lights. Play around with the values until you are satisfied with the picture. After that you may save the picture directly as a RAW tiff file (in 16 bit format) or normal JPEG pictures for display.

And the result can be very stunning indeed! Enough theories, let’s see some results.

Before I remembered to use HDR. This is the view from our hotel room, The Legend Melaka

Before I remembered to use HDR. This is the view from our hotel room, Avillion Legacy Melaka

After I remembered that I can use HDR…..

My initial reaction when I saw this picture was WHOOOAAA!!!!!

My initial reaction when I saw this picture was WHOOOAAA!!!!!

St Francis Institution, before HDR

St Francis Institution, before HDR

St. Francis Institution, after HDR

St. Francis Institution, after HDR

Before HDR

Before HDR

After HDR. Notice you see more details in the sky and the shadowy areas inside the AFamosa replica

After HDR. Notice you see more details in the sky and the shadowy areas inside the A'Famosa replica

Some pictures are not suitable for HDR. For example animate objects such as human, animals or other fast moving objects. Look at the guy in the foreground in the below picture:

Notice the ghosting of the guy in red?

Notice the "ghosting" of the guy in red?

Some dudes was walking in front of the fort, damnit!

Some dudes was walking in front of the fort, damnit!

Of course I can always remove them using Photoshop, but there are just too much work to do.

My HDR skill is still at its infancy. Wait a few more rounds, and I shall be more expert at it. In the meantime, go and check out my gallery!