Re: [Jmol-users] Manually colouring elements

[Robert H. <ha...@st...>]

sorry, "Brenton"!

On Wed, Oct 15, 2014 at 9:43 PM, Robert Hanson <ha...@st...> wrote:

> http://chemapps.stolaf.edu/jmol/zip/jmol-14.3.8_2014.10.15.zip
>
> Definitely better.  No more stray lines if the background is transparent,
> which is what counts.
>
> Do give this a try, Rolf.
>
> Still might find more ways to tweak the Floyd-Steinberg algorithm. I might
> take a look at what GIMP does and just copy that, but this was pretty fun
> to design, I have to say.
>
> Brandon, color dithering is when the number of unique colors is reduced to
> stay within some limit (255 in this case) and adjustments are made that
> approximate colors you do not have available. Your eye merges the color
> pixels to form colors that are not actually there. Think Renoir. It is
> really quite amazing. The red, green, and blue channels are separated, and
> a clever little algorithm does some "distribution of error" to do the magic.
>
> If you compare the two webcam images at
> http://chemapps.stolaf.edu/jmol/test/dither.htm you will see almost no
> difference. (Just click the 216 or 16777216 buttons.) I had no idea this
> was possible. What I figured out there was that rather than using 8 colors,
> we could use 216 (six for each color channel). The effect is an almost
> perfect reproduction, visually.
>
> Bob
>
>
> On Wed, Oct 15, 2014 at 6:11 PM, Robert Hanson <ha...@st...> wrote:
>
>> Well, dithering does produce artifacts. But they aren't visible
>> generally. If it is mangling the transparent color, though, that's
>> something I need to consider. That's probably a bug.
>>
>> On Wed, Oct 15, 2014 at 6:01 PM, Rolf Huehne <rh...@fl...>
>> wrote:
>>
>>> Am 16.10.14 00:29, schrieb Robert Hanson:
>>> > I don't know what the pink color is, but I'm guessing that is an
>>> > artifact of GIMP not transferring color. The dithering just can't do
>>> > that. Is what you have there, Rolf, a white background that you then
>>> > filled with color?
>>> >
>>> I added the pink color intentially as a second layer to make the dotted
>>> lines and holes better visible and then combined the two layers before
>>> saving.
>>>
>>> Regards,
>>> Rolf
>>>
>>>
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>>
>>
>>
>> --
>> Robert M. Hanson
>> Larson-Anderson Professor of Chemistry
>> Chair, Department of Chemistry
>> St. Olaf College
>> Northfield, MN
>> http://www.stolaf.edu/people/hansonr
>>
>>
>> If nature does not answer first what we want,
>> it is better to take what answer we get.
>>
>> -- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900
>>
>>
>
>
> --
> Robert M. Hanson
> Larson-Anderson Professor of Chemistry
> Chair, Department of Chemistry
> St. Olaf College
> Northfield, MN
> http://www.stolaf.edu/people/hansonr
>
>
> If nature does not answer first what we want,
> it is better to take what answer we get.
>
> -- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900
>
>


-- 
Robert M. Hanson
Larson-Anderson Professor of Chemistry
Chair, Department of Chemistry
St. Olaf College
Northfield, MN
http://www.stolaf.edu/people/hansonr


If nature does not answer first what we want,
it is better to take what answer we get.

-- Josiah Willard Gibbs, Lecture XXX, Monday, February 5, 1900