Luminous Landscape Forum
Raw & Post Processing, Printing => Digital Image Processing => Topic started by: CynthiaM on October 30, 2010, 05:47:19 pm
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When/how do you capture sharpen if processing hdr images? My understanding is that hdr programs will ignore anything you may have done in a raw converter to an image that is used for hdr processing. So what should one do about capture sharpening? I've even thought of just doing capture sharpening to a raw file and then converting to tiff and bringing in the tiffs to the hdr program. Any thoughts would be most appreciated.
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When/how do you capture sharpen if processing hdr images?
You need to differentiate between the HDR capture, and the subsequent tonemapping in postprocessing.
During the capture, and assembly, of an HDR file one typically interferes as little as possible (possible exception is glare reduction). Sharpening is postprocessing, and will typically be applied as part of the tonemapping.
My understanding is that hdr programs will ignore anything you may have done in a raw converter to an image that is used for hdr processing. So what should one do about capture sharpening?
Given the fact that multiple exposures can result in ghosting artifacts, I'd only capture sharpen after the merging of the individual exposures. Only if the de-ghosting algorithm, for some reason, does better with sharpened images, would I consider sharpening the individual captures (=unlikely).
There are benefits to using TIFFs as input for the merging of individual exposures (e.g. the possibility to vary the color temperature across the image).
I've even thought of just doing capture sharpening to a raw file and then converting to tiff and bringing in the tiffs to the hdr program. Any thoughts would be most appreciated.
In general, Raw data cannot be sharpened. At most one can alter the Raw conversion presets that are used by the Raw converter.
Cheers,
Bart
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Thanks for the reply. So if I understand you correctly, you let the HDR program handle the sharpening?
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If it were not possible to apply sharpening to RAW files then the entire concept of 'capture sharpening' would be useless.
If you want to make adjustments to the files before sending to the HDR app, then you can adjust the RAW files and export as TIFFs to the HDR software. If you're using Lightroom and using the Photomatix export, the files are converted to TIFFs as a part of the export process and any adjustments you've made to the RAW file in LR will be applied.
Given the detail enhancing properties of HDR software I, personally, wouldn't apply capture sharpening. You could end up with a pretty 'crunchy' looking result. The better way, in my view, to approach it is to think of the HDR as a new RAW file. Most HDR software apps have a Detail or similar type adjustment that acts to enhance detail (sharpening). Some, like Photomatix, have a Sharpening utility included. These are typically quite crude and rough so really shouldn't be used.
The best approach, I believe, is to get the tonemapping where you want it then apply sharpening as a two-step process (creative and output) rather than the current three-step trend. Alternatively, if you throttle back a bit on the detail enhancing/microcontrast features in the tonemapping, you can apply capture sharpening to the tonemapped TIFF file and retain the three-step process.
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If you want to make adjustments to the files before sending to the HDR app, then you can adjust the RAW files and export as TIFFs to the HDR software. If you're using Lightroom and using the Photomatix export, the files are converted to TIFFs as a part of the export process and any adjustments you've made to the RAW file in LR will be applied.
I have been fooling with a trial version of Nik's hdr Efex, which I have come to learn since my original post, also exports as tiffs as they go to the hdr program and does not ignore what you do in the raw converter as Nik recommends applying adjustments for chromatic aberrations in raw. So now I'm wondering if you should also make minor adjustments to exposure for example, if your darkest image still has blown out highlights, should you try to recover or if you brightest image still has blocked shadows, should you try to reduce the blacks if using something like Lighroom or Camera Raw.
I have never worked much with hdr but lately have been experimenting. HDR in CS5 is much improved in this regard and I always find Nik filters a pleasure to work with so I'm giving the process another look. I like hdr not so much for the surreal, fantasy, illustrative look but more for its ability to blend a broad dynamic range into a realistic looking image.
Any thoughts?
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Yes, Nik's LR plugin does that as well. It also picks up the XMP file settings if you invoke it directly from within PS.
Your darkest image shouldn't have blown out highlights for proper HDR merging. Given that Nik picks up RAW adjustments you could try using Recovery or opening shadows in your lightest image. If you're working with images already captured, there's nothing to lose. Going forward, a bit wider bracketing in the field would be the preferable route. You can never bracket too wide. You can bracket too narrow.