Hi folks,
Recently I have come across a couple of applications that export to a 32bit version of the DNG file format - DNG Float. Interesting, but not really very useable. However, there is some fun stuff going on that makes me think this might be a very useful, flexible file format in the photographic workflow - at least enough to try to figure out how I can use it.
I have been using a relatively new HDR application called LumariverHDR - it is similar in concept to Zero Noise, in that it merges the best pixels in a sequence of exposures into a single file (of various output formats) scaled to the darkest exposure. This, as we know, gives you noise free shadows. Couple this with the recent awesome dual ISO output of the Magic Lantern project and you have amazing flexibility in terms of increasing the dynamic range of your image capture, with the need for fewer source images to merge.
So, here is a quick example of a whacky workflow using two raw images, merged into a single DNG Float file, converted to 32bit TIFF and tone mapped in Float 32. This workflow looks very interesting and is a harbinger of things to come - 32bit raw files. In the below image example, there was no NR applied to the image at any stage of the workflow.
kirk
I posted this over in the Magic Lantern forum: http://www.magiclantern.fm …ic=9581.msg93303#msg93303
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I've managed to spend a little bit of time trying to find a useable workflow for DNG Float -> 32bit TIFF as outlined above, using the dng_validate application. Using the Mac version, I took a DNG Float file from LumaRiverHDR and ran it through dng_validate. The image data is a merge of two non-dualIso (regular raw) images into a single DNG Float - however, the same basic merging applies using the CeroNoice concept.
The output is the "-3" third stage file, a TIFF that has UniWB (all channel multipliers = 1):
I opened this image in Photoshop and used the Unified Color PS plug-in called 32Float to edit the 32bit TIFF. Here is the default tone mapped image in the 32 Float interface:
What is really nice about 32 Float is its 32bit white balance tool. In this test scene (shot a couple of years ago) I included a gray target - I click-white-balanced on it and got:
From 32 bit float I returned a 32bit image that I could then work on as usual in PS. I found that other methods of trying to massage the 32bit UniWB TIFF left a lot of green artifact. ACR accepts 32bit TIFFs but cannot handle the UniWB data - trying to WB the file is a disaster.
Here is the final image, after some adjustments in PS:
This method permits me to use my "standard" 32bit workflow, with some minor modifications at the beginning of the process. If one tried to convert a single, optimally exposed raw file of this scene, you could get the basic tonal range, but the shadows would be filled with noise that would ruin detail and tonal transitions in the shadows, especially under the table and in the jacket, for example. Even the relatively uniform wall tones would be riddled with noise that would smear and disrupt the gradual tonal transition and falloff of the window light.
Cool!
kirk
