Re: [CinePaint] Really basic script for batch converting.

On Tue, 24 Nov 2009, Frank Peters wrote:
>
> At the risk of sounding a bit arrogant and condescending, these people
> seem to be Photoshop dilettantes who don't really understand image
> processing.

It is quite true that there are many people who are very effective at 
using Photoshop who know little about image processing.

> You should not use forums as a primary source of information.  Consult
> professional texts (either online or hard copy) and limit forums only
> to supplemental information where a clear cut problem is addressed.

Does this list count as a "forum". :-)

>> 20/20/20 goes to 5120/5120/5120 > L=5120
>> 21/20/20 goes to 5376/5120/5120 > L=5197
>> 20/21/20 goes to 5120/5376/5120 > L=5274
>> 20/20/21 goes to 5120/5120/5376 > L=5147
>>
>> That's 4 levels of grey where in 8 bit you would have two (20/21/20 goes
>> to L=21).
>
> But relative to the total scale of 65536 levels these differences are
> minuscule and totally insignificant.  On a histogram they would cluster
> imperceptibly if not be totally within the same bin.

I agree with this.  It is interesting though that intentionally adding 
a tiny bit of gaussian noise while the image is still in RGB form will 
result in gray levels with more dispersion.  The image may not 
initially look much different to the viewer, but it will become more 
resistant to banding, and also more difficult to compress.  Sometimes 
the best way to limit later damage to an image is to intentionally 
inflict damage on it while it is still in pristine form.  With this 
technique, the amount of noise intentionally added needs to be more 
than whatever damage might be caused later due to processing, or 
insufficient bits/sample.

Bob
--
Bob Friesenhahn
[email protected], http://www.simplesystems.org/users/bfriesen/
GraphicsMagick Maintainer,    http://www.GraphicsMagick.org/

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