Ok as promised here’s the next part of my tutorial about DRI. I will talk about our source material and how we prepare it in Lightroom (you could use any other Raw converter) for the DRI step, where we will use Enfuse GUI for the blending. The image I showed in Part 1 is a DRI mapping of 3 exposures. When taking those shots I checked the histogram on my camera display to see if I’m covering the complete dynamic range of the scene. (An important thing I forgot to mention in Part 1 is, please do yourself a favour and shoot RAW. The quality of your final image will be better!)
This means that the histogram of the shot I exposed for the highlights should not be cut of on the right side. I suggest you turn on the overexposure warning of your camera to ensure this! Below you see that just directly beneath the clouds where the sun came out soon after, there are some hot pixels. Maybe I should have stopped down for an additional shot here but I think in this case this is not so big a problem because the white part there is just monotone sky which we can tone a bit later. If part of the clouds or a structured part ot the image would have been white in this shot then we would loose real detail.
For the image I exposed for the shadows on the other hand I want the histogram not to be cut of on the left side. You see here I got the whole detail in the foreground where above there were only black pixels.
Those two pictures are to far from each other in case of exposure for a good blending. We need some shots in between to get a good result. In this case I had just one shot which was exposed like I would do if I only had a single exposure for this scene. Here you clearly see that the dynamic range would have been to much for one shot!
Finally we will talk about the preprocessing of the images in Lightroom. There are just a few things we will adjust in the Basic and Detail settings. The following part assumes that you are familiar with Lightroom.
1. In the Basic settings we will use Exposure and Blacks to refine the histogram of each image a bit. For example we might decrease the exposure a bit for the first image since it’s still a tick to bright in the sky. We also want to adjust the White Balance since while working on the RAW image here this setting is still lossless.
2. Most important are the settings we make in the Detail window. First we increase the Amount to a value around 100 which will give the whole image more sharpness. Then we will use Masking and increase it to a value somewhere above 50 so the sharpening is only done to the edges. Holding down the Alt key while mooving the slider shows those edges. Depending on your image’s resolution you might adjust the Radius a bit but the value should be kept around 1.
The Noise Reduction we leave alone. You should take your images with the lowest ISO setting. The resulting longer exposures should be no problem since we use a tripod.
What’s very important though are the settings for Chromatic Abberation !! Look at high contrast areas in your image and you will notice some red or blue fringes. This means that in those parts different wavelengths of light are not alligned with each other what next to those fringes also leads to less sharpness in your image. So use the sliders Red/Cyan and Blue/Yellow to align those. You might not be able to remove the fringes completely by this so you can set Defringe to All Edges afterwards.
That’s essentially the preprocessing. Now go to File->Export and save the images to 16Bit Tiffs for the next step which will be the DRI mapping. Part 3 will deal with this!