I rarely need to use this technique anymore because the native dynamic range of modern Nikon digital cameras is so extensive that a native RAW file is all that is needed to obtain a full tonal range of highlights and shadows. To perform this demonstration here I had to purposely take a photograph that would be pushing the range limits of the camera. That itself proved difficult to do. The Nikon cameras - in this case a D750 -- are just so good that, if the exposure is set to obtain detail in both highlights and shadows, there is enough information to deal with the file in regular post-processing.
Nonetheless, I decided to give it a go, and set up a scene with a model looking into an open refrigerator at night. Normally, I would light this with some small flash units hidden inside the refrigerator and balance this light with some exterior bounce lighting for the overall scene. For this demo, I decided to use only the single, normal bulb that is inside the refrigerator. The room was completely dark save for some very low ambient light coming from a distant window.
The photo below is the final image. It is a composite of two images -- one processed in NX-D to bring out the fullest dynamic range, and the other processed in ACR to achieve good contrast as befitting such an actual scene, while also maintaining some of the shadow and highlight detail. Frankly, I probably could have come very close to this final result using just ACR and Photoshop alone, a testament to the range of the Nikon camera sensor. Nonetheless, an image processed with this technique will have more of a three dimensional quality and more extensive detail in both highlight and shadow ranges, not dissimilar to a subtle use of HDR, but without the false look that HDR often imparts.
|This is the final image combining both the Nikon Capture NX-D adjusted file and the Adobe ACR adjusted file with moderate Photoshop adjustments applied to the combination.|
The photograph is lit entirely by the one, refrigerator bulb plus a very small amount of natural room light from a distant window. The intensity and color of the room light can be seen in the upper corners of the photo below. The light on the model's back is the refrigerator light being reflected back onto her from a nearby wall. Other than this, no other light or fill was used for the shot. The exposure was 1/15 second at f/5.6 and ISO of 640.
The original, unprocessed RAW file below has highlights that, while too bright, do contain detail. Same goes for the shadows. Without this detail nothing can be done to correct the image so proper exposure placement is important. To that end I bracket the shot.
|This is the original RAW file right out of the camera exposed to preserve both highlight and shadow detail.|
Working in Capture NX-D I am only interested in bringing as much detail as I can to the overall image by using the Active-D feature. For this image I had Active-D set to high. I also tweaked some of the highlights and shadows with other controls. The final result from the NX-D process is an intentionally flat image with full detail.
Working in ACR (Adobe Camera RAW) I brought out the highlight detail as much as possible. On this image I intentionally leave the contrast high because I will need it later when the very flat NX-D image is merged with this file. Both images are output as 16-bit tif files to provide the most amount of working depth.
The ACR is brought into Photoshop first. Next the processed NX-D tif is put on top of the ACR file as a separate layer. Turning down the opacity of this layer determines how much of each file is included in the final combination. In this case, I used 33%. The ACR file is providing the contrast, and the NX-D file is providing extra detail to both the shadows and highlights. As can be seen in the Photoshop layer masks below some further tweaking was needed to combine the two images. A final curves layer was added as a subtle, final adjustment. You can see where I held back some of this adjustment from the brightest area of the refrigerator by painting black on the curves adjustment mask.
|This shows the two image layers combined in Photoshop with a final curves adjustment on top. That is all that was needed to finally merge these two images into one.|
The idea going into this scene was to obtain a final image that preserved the true feeling of late night kitchen light from a refrigerator without completely losing all the highlight and shadow detail. Having recourse to this post-processing technique combined with the already excellent dynamic range of Nikon cameras made the setup of the scene simple. All I needed was a tripod. The refrigerator bulb provided all the necessary lighting. It doesn't get any simpler than that.