Tonemapping

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Processing the photos part 1

In this series of web pages, I have documented the process which I currently use to create 360x180 degree panoramas. This page explains how I use tonemapping to increase the detail visible in both bright and dark areas in my photographs. The software which I use for tonemapping is Luminance HDR, which is free software and can be downloaded from this link. This is an entirely optional step, which you can skip if you want to. The next three pages deal with editing the nadir, stitching using Hugin and creating a panosphere.

Tonemapping the images (optional)

When I am not taking panoramic photographs, another hobby of mine is to create HDR or tonemapped images using Luminance HDR. By reading the raw Canon "CR2" files into Luminance HDR and tonemapping them, I can display details in an image that I could see when I took the photograph, but which are not normally possible to display with the reduced dynamic range of a computer display or printout. See the Wikipedia article on tonemapping for more information.

Tonemapping can be time-consuming when processing one image at a time, seeking out the optimum settings for each image. Given that I collect nine photographs in the same place, with the same camera settings and I want to produce a uniform result, I do not need to process one image at a time, since Luminance HDR has a Batch Tone Mapping option.

In Luminance HDR there are various tonemapping operators. Reinhard '02 gives relatively natural-looking results. Fattal and Matiuk both give more obviously manipulated results. Fattal is very colourful and Mantiuk picks out texture. The procedure I use is as follows:

    • Start Luminance HDR.
    • Load a raw image using the "Load HDR image..." option.
    • Set the tonemapping operator to Reinhard '02.
    • Set the output resolution to the maximum available and click the Tonemap button to create a tonemapped image.
    • If the settings give the desired result, save the settings to file, otherwise, change the settings and try again, eventually, saving the final settings to file.
    • Start the Batch Tone Mapping wizard from Tools | Batch Tone Mapping...
    • Add the nine raw files using the + button.
    • Load the Tone Mapping Settings from the text file using the right hand + button.
    • Select the Output Folder using the Select... button.
    • Click Start.

This process is surprisingly quick compared to doing the job one image at a time, but on my laptop, the process still gives me time to make a coffee. This procedure is not necessary, but in my view it gives better results in most circumstances.

The next three pages deal with editing the nadir, stitching using Hugin and creating a panosphere.

Batch tonemap