Processing X-Tran files for High Dynamic Range

Capturing the files with an XT-1

When I want to make sure I have sufficient dynamic range captured I use the XT-1 Bracket setting on the shutter function dial. I have bracketing set to maximum EV range. Unfortunately that means only one stop under and one stop over.

Another option is to use the exposure compensation dial. That requires the camera is tripod mounted and the photographer is careful when turning the dial to ensure not moving the camera.  I rarely use this capability since most of these extended dynamic range sets are shot hand heldI have my XT-1 set to save raw files and also fine JPGs. The main reason for the JPGs is to have better zooming capabilities on the LCD. For this processing test I imported the 0EV JPG to  compare with the three options I used when processing the raw bracket set.

Here is the camera JPG with processing applied.

Camera JPG with Lightroom adjustments applied. Then corrected for Exposure and minor color.

Camera JPG with Lightroom adjustments applied. Then corrected for Exposure and minor color.

The image was shot with a 10-24 zoom at 10mm and F5.6. I corrected the verticals in Lightroom. I selected this image for this processing test primarily because it has interior lights as well as a bright outdoor street visible through the large front window. There are also deep shadow areas under the desk and in the clothing rack on the back wall. With the clipping mask enabled in Lightroom Develop Module I set the white point so there is some clipping on the highlights on the care and the black point to block up the shadow under the desk just enough to make sure there is some true black. That also causes just a bit of shadow clipping around the dark suit coats on the back wall. In the full image in Lightroom the light fixtures are not clipped. The shape of the bulb inside the squarish globes is apparent.

Lightroom Processing

I’ve built a number of processing presets for Lightroom that I use for importing raw files. My first choice (defualt) import preset is based on the Adobe XT-1 Astra camera profile. I have the highlight slider set to minus 50 and the shadow slider set to plus 50. The clarity slider is set to plus 25.

For this processing test I adjusted the highlight slider to minus 100 and the shadow slider to plus 100 and the clarity slider to zero for the first bracket import into Photoshop CC 2014.  I also checked white balance with the eye dropper on the 0EV frame and used the result to set the white balance for the other two frames in the bracket. The only reason for importing the bracket into Photoshop is so it can create a 32 bit floating point TIFF file for use in Lightroom. The 32 bit file expands the range of the sliders in the Develop Module, at least those that have to do with exposure, and tonal range. I named the resulting 32 bit file “HDR test 1”.

The only change for the second version was to set all the sliders to 0 in the basic window in the Develop Module. The resulting 32 bit file was named “HDR test 2”. These 32 bit files provide a much wider range for processing in Lightroom without getting some of the side effects that can be introduced with HDR tone mapping. Since I have the Nik suite of plug-ins for Photoshop, I opened the bracket in Nik EFX HDR Pro. I left the HDR Pro setting at their defaults for the realistic preset and saved the TIFF file. HDR Pro saves the TIFF as a 16 bit file. I did not find an option to save it as a 32 bit floating point file.

I then used Lightroom Develop Module capabilities to process the 32 bit file. I fiddled with Exposure, Contrast, Highlights, Shadows, White Point, Black Point, Clarity and Vibrance. I set the white and black point to show just a few pixels of clipping. I used contrast and clarity to bring back some punch in the tone curve. I also used the color sliders to adjust hue, saturation and luminosity in the red, orange, yellow, blue and green channels to clean color casts and to lighten or darken various part of the image. For example, I decreased luminosity in the yellow channel to darken the floor a bit. I used hue, saturation and luminosity to control a red cast in the side of the desk and some of the other dark wood.

I pasted the Develop Module setting from the first test to the others and then made minor adjustments to each of the others.  The final test was with the over exposed bracket frame processed in Lightroom starting with the same Develop Module settings and then adjusting them.

There are differences, but I’m going to let you explore them yourself. These JPGs, exported from Lightroom with screen output sharpening show most of the subtle differences. There are a few that are nearly impossible to see because of the smaller size.

Test 1

32 bit file with highlights and shadows sliders at 100.

32 bit file with highlights and shadows sliders at 100.

 

Test 2

32 bit file with 0 exposure adjustments

32 bit file with 0 exposure adjustments

 

HDR Pro Tone Mapped

3 files combined using EFX HDR Pro some HDR processing and then final adjustments in Lightroom started by applying processing setting from Test1

3 files combined using EFX HDR Pro some HDR processing and then final adjustments in Lightroom started by applying processing setting from Test1

 

+1EV bracket frame with same processing

Over exposed bracket with Lightroom processing.

Over exposed bracket with Lightroom processing.

Conclusions

Any of these processing options will work with a similar scene. Which one is best may depend on the scene’s subject content more than the overall dynamic range. i.e. a need to keep detail when most of the scene is above mid-tones or the opposite. This kind of scene also shows the problems with daylight and artificial light for getting a good white balance throughout the image. Most of the time, I’ve found I can get an acceptable image using Lightroom capabilities from one of the three bracket frames without resorting to creating the 32 bit file.  I almost never use HDR tone mapping software.

ENJOY!