PanoTools NG:
Re: Re: Sigma 8 F3.5 and its sharpness
Eric O'Brien 2007-May-15 20:15:56
Another thing to consider is that sharpening is accomplished by
increasing the contrast between adjacent pixels. Remapping from a
fisheye to equirectangular projection will STRETCH those adjacent
pixels, in effect smearing the sharpening. The effect will be
greater the more the original pixels need to be stretched, so any
residual sharpening will vary across each source image.
I don't know how visible this would be in reality, but this is why
*I* sharpen last.
It could be that a very light first sharpening of the source image
would be "proper," but that too would be degraded by the subsequent
remapping.
As an aside: when doing noise removal however, it is suggested to do
this as EARLY in the processing steps as possible. Noise is very
much related to the sensor itself and the algorithms in the various
noise removal tools have presumable been "tuned" to remove the
patterns of noise found in an unmodified source file.
eo
On May 15, 2007, at 6:13 AM, Alex wrote:
> John, why apply sharpening AFTER stitching? Is there a big difference
> as opposed to sharpening the source images first?
> Alex
>
>
> John Houghton wrote:
>>
>> --- In #removed#
>> <mailto:PanoToolsNG%40yahoogroups.com>, "udedomenico"
>> <udedomenico@...>
>> wrote:
>>> OK I guess things can get better if you extract the pic from the
>>> RAW file and get rid of some chromatic aberration....
>>>
>>> but is that all?
>>
>> You will certainly get a very much improved image if you extract tiff
>> files from RAW with properly corrected chromatic aberration, and
>> apply
>> some intelligent sharpening after stitching.
>>
>> John
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