[Digikam-users] canon eos20d and unsharp mask

Andrew Atrens atrens at nortel.com
Tue Jan 30 15:43:44 GMT 2007


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Hi folks,

I'm processing raw images captured with my EOS20D ..

Canon puts out a quick reference guide for 'tips and tricks for
maximum image quality' in which they advise -

"Canon EOS digital cameras have an anti-aliasing filter installed on
the image sensor.  This filter improves color rendition and
practically eliminates moire. The liability  is a slight reduction of
sharpness. To reduce the softening effect of the anti-aliasing filter
we recommend applying an unsharp mask to the image in Adobe Photoshop.
Although there is no such thing as a 'best' setting for all
applications, we suggest the following as a starting point"

 Amount: 300%
 Radius: 0.3 pixels
 Threshold: 0 pixels

I'm noticing that the digikam unsharp mask plugin has a minimum
'radius' of 1 pixel. Which seems more intuitive than '0.3' pixels.

So I have two questions:

Firstly, do the above PhotoShop setting parameters (roughly) map 1:1
with digikam's unsharp mask parameters?

And secondly, can someone recommend some general guidelines for using
unsharp mask? - Unless I ask the camera to do the sharpening
'in-camera' using 'Parameters' settings, I think I'll need to apply
this to every raw photo I take. After staring at a photo for a while,
one begins to second guess one's instincts about what settings 'work
well' and which ones don't.

Thanks,

Andrew.

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