On Mon, 7 Mar 2005, Eric Pierce wrote:
> The level tool's black input slider and the white input slider must
> adjust in relation to the blur radius, and that's where I'm stuck.
> Now I did some manual sampling of different blur radius to see if I
> could find a relation between the blur radius and the black/white slider
> settings. My results make what looks like a y=1/x^2 type graph, but it
> needs a little tweaking.
> Here's my data.
> Radius Black White diff (White - Black)
> 0 0 255 255
> 2 70 183 113
> 4 93 160 67
> 6 102 151 49
> 86 125 128 3
> 88 125 128 3
> 90 125 128 3
> Now if I can just figure out the relationship (i.e., equation) between
> the radius (1st column) and the diff (4th column), that should be all I
> need to determine what the black/white slider settings should be for all
> cases. My best stab is 'diff=(1/radius^2)*255*radius'. But this
> produces slightly skewed results.
As I see it, you have all the data you need. Make an array with your
experimental results and use that. Just do an interpolation where needed
(for the odd blur radius). There is no point in trying to find a
mathematical model for this, if you already know everything you need.
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