On gnuplotting.org, the presentation of color palettes includes the raw data to replicate the plots displayed there. Likely known to whose using gnuplot for longer, I recognized the representation of the third dimension, and overall perception of the maps plots depend on calling the quantity 'directly', e.g.
In my perception of using the cubehelix palette and in reference to the 'direct output', small z-values more than proportionally benefit from the square-root transformation; they seem to be «lifted» from the otherwise more dark region of the palette. Applying the logarithm on z equally yields a brighter plot in general; though areas with larger z-values, already displayed with more brightness, than others, seem to gain more brightness, than the areas with lower z-values.
My two questions are:
Is applying such transformations already considered as a kind of filtering, similar to low-pass filters in acoustics?
If so, is there a name commonly used to describe the processing better than for example "data were displayed as their square-root transformation"?
On gnuplotting.org,
the presentation of color palettes includes the raw data to replicate the
plots displayed there. Likely known to whose using gnuplot for longer, I
recognized the representation of the third dimension, and overall
perception of the maps plots depend on calling the quantity 'directly', e.g.
~~~
plot 'test_colormap.txt' u ($1/3.0):($2/3.0):($3/1000.0) matrix with image
~~~
or 'square-root transformed',
~~~
plot 'test_colormap.txt' u ($1/3.0):($2/3.0):(sqrt ($3/1000.0)) matrix
with image
~~~
or 'logarithm transformed'
~~~
plot 'test_colormap.txt' u ($1/3.0):($2/3.0):(log ($3/1000.0)) matrix with
image
~~~
In my perception of using the cubehelix palette and in reference to the
'direct output', small z-values more than proportionally benefit from the
square-root transformation; they seem to be «lifted» from the otherwise
more dark region of the palette. Applying the logarithm on z equally
yields a brighter plot in general; though areas with larger z-values,
already displayed with more brightness, than others, seem to gain more
brightness, than the areas with lower z-values.
My two questions are:
Is applying such transformations already considered as a kind of
filtering, similar to low-pass filters in acoustics?
If so, is there a name commonly used to describe the processing better
than for example "data were displayed as their square-root transformation"?
Thank you very much for telling me the keyword missing and indicating
the address. The background and examples the site and its siblings
provide (e.g., the Italian and Dutch analogue apply the technique on
color images, too) are very helpful for me; they answer my questions.
On gnuplotting.org, the presentation of color palettes includes the raw data to replicate the plots displayed there. Likely known to whose using gnuplot for longer, I recognized the representation of the third dimension, and overall perception of the maps plots depend on calling the quantity 'directly', e.g.
or 'square-root transformed',
or 'logarithm transformed'
In my perception of using the cubehelix palette and in reference to the 'direct output', small z-values more than proportionally benefit from the square-root transformation; they seem to be «lifted» from the otherwise more dark region of the palette. Applying the logarithm on z equally yields a brighter plot in general; though areas with larger z-values, already displayed with more brightness, than others, seem to gain more brightness, than the areas with lower z-values.
My two questions are:
See "gamma correction", e.g. Wikipedia
https://en.wikipedia.org/wiki/Gamma_correction
On Wed, Dec 11, 2019 at 4:01 AM Norwid Behrnd nbehrnd@users.sourceforge.net
wrote:
Thank you very much for telling me the keyword missing and indicating
the address. The background and examples the site and its siblings
provide (e.g., the Italian and Dutch analogue apply the technique on
color images, too) are very helpful for me; they answer my questions.
On Wed, 11 Dec 2019 16:57:49 -0000
"Ethan Merritt" sfeam@users.sourceforge.net wrote: