HDR photography is a great technique to create stunning photos, but lets be honest it does have a few draw backs. One major drawback to HDR is ghosting, which is caused by movement while bracketing your photos. Sometimes this can create a very interesting look, but other times it can be very unappealing. One way to avoid ghosting is to take a single photo and tone map it rather than taking a series of bracketed shots. Its a really easy way to give your photos an HDR look, when you forget or can't bracket your images.
For this posting I am going to be referring to this technique as HDR. I know their is much debate about weather or not this is HDR. I may touch on this debate in the future, but for now we will call a single tone mapped image HDR for the sake of keeping things simple.
Capturing your Source Image
If your planning on using this technique you should try to find a scene that has low to medium contrast. The lower the contrast the better this will work. You can determine the contrast by finding the darkest and brightest parts of your scene. If the difference is extreme, your scene probably has a high contrast. For high contrast scenes you should bracket your shots. Single photo HDR will not work properly for high contrast type scenes. Once you have determined the contrast of your scene you will want to capture your source image as a RAW file. RAW has a slightly larger dynamic range than JPEG and will be more resistant to noise. Noise is a major problem with single photo HDR which is also why you should shoot at the lowest ISO setting possible.
Processing Your Source Image
To get the best results you should convert your RAW photo using a RAW converter, you should not use tone mapping software to do this. Once you have your file opened in your RAW converter you can make the adjustments you would like and then covert and save the image as a TIFF. That is just one way of doing it, some people prefer to import their image into the RAW converter three times. One of the times they will adjust the RAW file to an exposure of -2, the second time +2 and the third time they will not make any adjustments. This will create three images that are identical except for the exposures, which should all be different.
Depending on which way you choose to process your RAW file you should now have 1 or 3 TIFF files. (UseJPEG files if your tone mapping software does not work with TIFF files) Now it is time to open your tone mapping software and upload your files. When you open the your files in the tone mapping software a warning may come up stating to specify the number of stops between the exposures. If this occurs simply input -2, 0, and +2. After this point you can essentially use the same process that you would use when tone mapping a series of bracketed photos.
Summary
Single photo HDR may not be true HDR, since it doesn't work with images that have a high dynamic range. However, its a fun way to work with photos you have taken in the past before you knew how to bracket photos for HDR. When I first learned about this I had a great time going through my old photos and experimenting with how I could improve them with tone mapping. I hope you give this a try and post some of your results to our site. Hope to see your work, and who knows it could even win our monthly contest!
