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Sharpening

John Reeves

New member
Hello all

I was wondering what everybody’s opinion is on sharpening.
Is there actually any point in doing it in the RAW convertor (LR) before exporting?
I use CS3 by the way for final adjustments.
 

Cem_Usakligil

Well-known member
Hi John,

Welcome to OPF, I hope you'll like it here. Please drop by the "Introduce Yourself" forum and do just that :).

Re. your question, I'll provide my input on this later today but I have to rush to a meeting right now.


Cheers,
 

JohanElzenga

New member
A good method is to split sharpening into two steps: First, you sharpen the images slightly just to remove the effect of the anti-alias filter of the camera. That kind of sharpening is done in the RAW converter and is called 'Capture Sharpening'. The second time is when you prepare your image for output. This time you sharpen specifically for the type of output, so if you print on an inkjet printer you sharpen differently than if it's a small image for display. This 'Output Sharpening' will be done in CS3 in your case.
 

Cem_Usakligil

Well-known member
Hi John,

I am back as promised. Johan is quite correct but knowing his great reputation here in the Netherlands what else could we expect from him? :)

As you might already know, some people divide sharpening into three groups: capture, creative and output.

We need to compensate for the softness introduced to any image by the digitization process (such as the AA filter Johan mentioned). So therein lies the role of the so called capture sharpening. I too use LR but I try to stay away from the sharpening in LR itself unless the images are for web only. The reason is that I do not like the way this USM-like sharpening works on the raw images. It introduces too much halos and speckles/mozaics for my taste. I prefer to work with other methods of sharpening such as using deconvolution. Some specialist converters such as DxO claim to do the capture sharpening properly and from what I have seen they do indeed a better job at it than the LR.

I won't go into creative sharpening or the output sharpening yet since your original question was regarding the capture sharpening. Unless you want to discuss further of course :).

Cheers,
 

Daniel Buck

New member
I do all my sharpening after I've processed the image, and sized it to my print resolution. That seams the least destructive, and problematic to me.

I don't think there is any benefit to sharpening before you process and resize (larger, or smaller), I would guess that it's actually worse to sharpen before you process/resize, but I don't know for sure that it is. I've found that resizing images that have been sharpened, don't look as smooth, the interpolation seems to make effects of sharpening show up a bit ugly sometimes. I just sharpen once the image is ready to print, and that's been great. I convert the RAW file with zero sharpening, and zero noise reduction. Same thing when scanning film, I don't do any sharpening to the scanned file until I'm at my print resolution. It seems to work out best that way, and doesn't show the grain quite as much.
 

JohanElzenga

New member
As you can see, opinions differ just as tastes differ. There is no 'correct' way of doing this, just your preferred way. To me, the advantage of doing a slight capture sharpening in the RAW converter is that you are doing it in the conversion process and that it's non-destructive. It also mean that I don't use any extra sharpening for images that are meant for display on screen, so it speeds up my workflow. In Lightroom 1.0 I wouldn't use sharpening because it was too primitive. In Lightroom 2.0 things have improved dramatically. Use a very low radius to avoid halos. A radius of 0.5 is enough.
 

Cem_Usakligil

Well-known member
As you can see, opinions differ just as tastes differ. There is no 'correct' way of doing this, just your preferred way. To me, the advantage of doing a slight capture sharpening in the RAW converter is that you are doing it in the conversion process and that it's non-destructive. It also mean that I don't use any extra sharpening for images that are meant for display on screen, so it speeds up my workflow. In Lightroom 1.0 I wouldn't use sharpening because it was too primitive. In Lightroom 2.0 things have improved dramatically. Use a very low radius to avoid halos. A radius of 0.5 is enough.
Hi Johan,

I assume you mean by non-destructive that it is not applied to the RAW image but only to the tif/psd/jpg file one creates as a result of the conversion? Upon reading your post I thought that you were referring to manipulating the data in the RAW pipeline but I maybe I was too enthusiastic. Does the capture sharpening of LR indeed operate on the RAW data in the pipeline before it is converted into pixels? I have read many discussion on this RAW pipeline issue but I could not find any conclusive answers.

Cheers,
 

John Reeves

New member
Thank you

Many thanks everybody for your advise.
Up to now I have always sharpened only in CS3 Just was curious to know why the option to sharpen was available in LR You have helped me understand, thank you.
 

JohanElzenga

New member
I assume you mean by non-destructive that it is not applied to the RAW image but only to the tif/psd/jpg file one creates as a result of the conversion? Upon reading your post I thought that you were referring to manipulating the data in the RAW pipeline but I maybe I was too enthusiastic. Does the capture sharpening of LR indeed operate on the RAW data in the pipeline before it is converted into pixels? I have read many discussion on this RAW pipeline issue but I could not find any conclusive answers.

Sharpening is applied to the pixels, because you couldn't sharpen the RAW data itself. Sharpening is basically increasing the edge contrast, but before you have demosaiced, you do not know what the true edges are. For example: if you shoot a plain red object, all the red sensor sites will generate high RAW values, and all the green and blue sensor sites will generate low RAW values. That has nothing to do with edges though, it is simply the result of using a Bayer filter on your sensor. The reason this sharpening is called non-destructive, is because it does not change anything in the RAW file.
 

Cem_Usakligil

Well-known member
Hi Johan,

Thanks for confirming my conclusions:
- sharpening is not done in the RAW process, but after the image is de-Bayerized
- Non-destructive refers to the fact that the RAW file is not changed

But eventually, the resulting file from the RAW conversion (tif, jpg, psd, etc) is capture sharpened and that conversion is by definition "destructive", in other words the capture sharpening changes the pixels. OK, I'll stop playing with semantics now ;-)

Thanks again :)

Cheers,
 
Hi Johan,

Thanks for confirming my conclusions:
- sharpening is not done in the RAW process, but after the image is de-Bayerized
- Non-destructive refers to the fact that the RAW file is not changed

But eventually, the resulting file from the RAW conversion (tif, jpg, psd, etc) is capture sharpened and that conversion is by definition "destructive", in other words the capture sharpening changes the pixels. OK, I'll stop playing with semantics now ;-)

Ah, but semantics can be important!

There is a difference in how sharp the Raw conversion turns out. The Bayer CFA demosaicing is an operation with many trade-offs between artifacts and sharpness (false color and mazing). So one could say hat there is a certain amount of sharpening being done in the Raw conversion itself, in all converters, to varying degrees (sometimes adaptive to image detail).

Given that RGB converted image, there are different approaches possible. The preferred method generally has as much to do with personal preference as with workflow. However, there are objective ways (not always simple ways) of determining the best approach, depending on the goal.

In general one can say that for downsampling, pre-sharpening doesn't help. On the contrary! So if one's goal is to produce a smaller (in Megapixels) image, I'd suggest to leave all sharpening out of the equation, just go with an unsharpened Raw conversion.
Only(!) if one uses the best algorithms for downsampling, then some (capture) sharpening won't hurt much, if any. Photoshop e.g. currently does not use the best quality algorithms.

For upsampling/magnification e.g. for large prints, one can apply capture sharpening before interpolation, as long as the sharpening doesn't create visible artifacts(!). If, and how much, one can sharpen prior to magnification, is dependent on too many factors for a general approach. Some algorithms for magnification do better with pre-sharpened image data than others, also depending on image content.

A good series of resampling algorithms is offered by ImageMagick, and they currently offer some 12+ different algorithms, with additional parameters. Some are better out-of-the-box for downsampling, others for upsampling, some for line-art or text, others for photographic images.

Of course, output sharpening at the final size is (assuming proper execution) always beneficial for the best output quality. Although even then one has to consider things like which spatial frequencies to enhance, and should dithering/noise be added.

Bart
 
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