(Just to you, because I don't want to expose my ignorance any further than I
have to.)
I can see the value (pun intended) of having a grayscale palette that shades
smoothly from white to black. For example if I'm preparing a bar chart for
publication: I want to pick N different shadings that will be distinguishable,
and I want to arrange them such that the difference from bar to bar is
maximized. That is, five bars arranged 0.00, 0.50, 0.25, 1.00, 0.75 seems
better than 0.00, 0.25. 0.50, 0.75, 1.00, on the theory that 0.50 is clearly
darker than its surrounding 0.00 and 0.25, 0.25 is clearly lighter than 0.50
and 1.00, etc., so the bars will be distinguishable. But I haven't actually
made up such a chart.
As a user of color palettes, I want to say "I need N distinct colors, and have those look nice
whether they are in color or in grayscale". There might be more to this than just
"value". E.g., if I want 3 colors, can they be red, yellow, and blue? The primary
colors. If I want 6 colors, can I get orange between the red and the yellow, green between the
yellow and the blue, and purple between the blue and the red? Or is rainbow order just an accident
of wavelength and not to be trusted? This seems more a matter of art than of numerics.
In your GRB clock, I see what appears to be two areas of green: from 2 to about
2:30, and then again from 4 to about 5:30. The RGB clock has only one region
of cyan. That seems confusing, but maybe I'm not meant to pick N colors from
the clocks by choosing even intervals around the clock.
Why does the GRB clock seem to have a smaller slice of cyan than the RGB clock?
I'm always afraid these tests reveal more about my eyes and brain than about
the colors themselves. That would be a problem if my eyes are different from
everyone else's. yet another reason to rely on artists to pick colors for me.
... peter
On 03/31/14 16:55, Linda Alvord wrote:
Here's some information to ponder concerning grayscale images. "Value" is a
very important aspect of color. All the computer colors depend on Red, Green
and Blue light. However, Green is brighter than Red. So life would be
simpler if we lived in a computer world which had number triples in GRB
order. There are 5 different images created here. Because they are being
timed, there are two of each image. Compare RGB and GRB. Compare Gray
RGB and Gray GRB . The final image is a different strategy for obtainin a
grayscale image.
require 'viewmat'
at2=: 13 :'([:{:"1 *.) j./"1 y'
RGB=: 255* #:i.8
GRB=:1 0 2{"1 RGB
we=: 13 :'<.0++/"1[0.3 0.59 0.11*"1 y'
gray=: 13 :'3#"0 we y'
ts=: 6!:2 , 7!:2@]
ts 'RGB viewmat (D=.at2"0 /~ i:500);''RGB Clock'''
ts 'GRB viewmat (D=.at2"0 /~ i:500);''GRB Clock'''
ts '(gray RGB) viewmat (D=.at2"0 /~ i:500);''Gray RGB Clock'''
ts '(gray GRB) viewmat (D=.at2"0 /~ i:500);''Better Gray GRB Clock Linda
Alvord'''
RM=: (# # +/ % #)"1
ts 'RM(3#"0 i.255) viewmat (D=.at2"0 /~ i:500);''Better Gray Clock Raul
Miller'''
I am looking for the bes possible way to introduce the topic of color images
and their grayscale images. Also, in the next examples I would like to show
the value of "value" in analyzing numeric data. Please send any ideas that
might be useful.
Linda
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Linda Alvord
Sent: Monday, March 31, 2014 12:35 AM
To: [email protected]
Subject: Re: [Jprogramming] Challenge 14; Colorful Creations
require 'viewmat'
at2=: 13 :'([:{:"1 *.) j./"1 y'
]P8=: 255* #:i.8
]Q8=:1 0 2{"1 P8
ro=: 13 :'<.0.5+y'
we=: 13 :'+/"1[0.3 0.59 0.11*"1 y'
gray=: 13 :'3#"0 ro we y'
ts=: 6!:2 , 7!:2@]
ts '(gray P8) viewmat (D=:at2"0 /~ i:1000);''Better Gray Clock'''
RM=: (# # +/ % #)"1
grayRM=:RM P8
ts 'RM(3#"0 i.255) viewmat D;''Better Gray Clock Raul Miller'''
Q8=:1 0 2{"1 P8
grayLA=: 13 :'1 0 2{"1 y'
ts '(gray Q8) viewmat D;''Better Gray Clock Linda Alvord'''
Both images look quite good. Is there some way to determine which is the
better image or are they the same?
Linda
-----Original Message-----
From: [email protected]
[mailto:[email protected]] On Behalf Of Raul Miller
Sent: Sunday, March 30, 2014 4:17 PM
To: Programming forum
Subject: Re: [Jprogramming] Challenge 14; Colorful Creations
Like this?
(3#"0 i.255) viewmat D;'Grade from white to black, clockwise from North'
Thanks,
----------------------------------------------------------------------
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