Join Tim Grey for an in-depth discussion in this video Choosing a conversion mode, part of Learning HDR (2012).
When you're using HDR Pro in Photoshop to assemble your high dynamic range images, one of the first decisions you need to make is which mode you'll use for converting the image. The mode you choose determines which specific adjustments are available to you. Let's start off by taking a look at the Bit Depth option. Our choices include 32-bit, 16-bit and 8-bit. I recommend never using the 8-bit option because it simply doesn't give you as much fideility, there's a higher risk of posterization and you won't retain quite as much detail throughout the shadows and highlights in the final image.
So generally speaking, I would work with 16-bit; that gives us a much wider range of tonal and color values to work with And helps reduce the risk of posterization. I think of 32 bit as a specialized option. If you're working in 32 bit mode, you'll only have the option to adjust the overall white point for your final image. So that doesn't give you much flexibility. Generally, I would only use 32 bit if I were going to do some specialized adjustments later. Such as with a third party application for HDR toning. If you're working in the 16 bit or for that matter 8 bit mode you can also choose which particular mode you're going to use for processing the data in your image.
The default and the option that I use for all HDR images is local adaptation and that gives us the maximum number of controls for fine tuning the overall appearance of your HDR image. The Equalize Histogram option doesn't give you any controls at all. It's simply applying its own math to obviously equalize the histogram to distribute the tonal values somewhat evenly within the photo. Sometime you might like the result of the Equalize Histogram option but you don't have any options for adjusting the appearance of the photo other than to work on the image after the fact in Photoshop.
The next option is Exposure and Gamma, and as the name implies, this option only gives you two adjustment controls. The Exposure control, and the Gamma control. So, you're only able to adjust the overall white point, as well as the overall brightness using a mid-tone curve. These adjustments are also available when you choose the local adaptation option and so I don't tend to use Exposure and Gamma. And finally, we have Highlight Compression. And here again, we don't have any adjustment controls and so I don't intend to use highlight compression either. Although it's not a bad idea to take a look and see if it's an effect that you like for a particular image.
So that means, in most cases, you'll probably find yourself, like me, using the local adaptation option in conjunction with the 16 bit per channel mode. You can then use all of the various adjustments in order to fine tune the image and create your final HDR.
- Capturing, reviewing, and organizing HDR images
- Maximizing detail in a single image
- Simple single-image HDR
- Assembling from Bridge or Lightroom
- Choosing a conversion mode
- Using presets
- HDR Pro adjustment options
- Using Nik HDR Efex Pro
- Using Photomatix