GR colormaps

[tbreloff]

@jheinen It seems like colormaps in GR are hardcoded? Is there a way that I can override the default maps with custom ones? I'm working on plotting images, and it's not taking my grayscale colormap:

[tbreloff]

Also BTW... this example is about 100x faster than PyPlot...

[tbreloff]

Also sort of related... it seems that heatmaps do interpolation by default... is it possible to turn on/off from within Plots?

[tbreloff]

One more thing I just noticed... I have yflip=true for the image above, and the colorbar is flipped as well. Can that maintain it's orientation separate from the y-axis?

[tbreloff]

I found another weird behavior... when I try to plot a scatter on top of the image (currently a heatmap linetype), it adds the scatter to the colorbar! Clearly the colorbar is being set to the "current axis" or something like that...

[jheinen]

@tbreloff : In GR there is a drawimage() routine which requires RGBA encodes 32-Bit integers. First of all, the gr.jl backend has to recognize the image object, then it must be converted into the RGBA representation.

Not a big deal, but, as I never used Image.jl before, give me some time and I'll add the missing code.

[tbreloff]

I'm not asking you to support images... I'm asking how to set the colormap. We get lots of functionality beyond just images if GR can use the Plots.ColorGradient (and images will work right away)

We can worry about native support for images another time.

On Saturday, May 7, 2016, Josef Heinen notifications@github.com wrote:

@tbreloff https://github.com/tbreloff : In GR there is a drawimage() routine which requires RGBA encodes 32-Bit integers. First of all, the gr.jl backend has to recognize the image object, then it must be converted into the RGBA representation.

Not a big deal, but, as I never used Image.jl before, give me some time and I'll add the missing code.

— You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub https://github.com/tbreloff/Plots.jl/issues/225#issuecomment-217630818

[jheinen]

In GR, there are 44 predefined colormaps, each containing 256 colors (color indexes 1000 - 1255).

using GR
y = 1.0
for cm in 0:43
  setcolormap(cm)
  cellarray(0, 1, y, y-0.02, 256, 1, collect(1000:1255))
  y -= 0.025
end

COLORMAP_UNIFORM = 0
COLORMAP_TEMPERATURE = 1
COLORMAP_GRAYSCALE = 2
COLORMAP_GLOWING = 3
COLORMAP_RAINBOWLIKE = 4
COLORMAP_GEOLOGIC = 5
COLORMAP_GREENSCALE = 6
COLORMAP_CYANSCALE = 7
COLORMAP_BLUESCALE = 8
COLORMAP_MAGENTASCALE = 9
COLORMAP_REDSCALE = 10
COLORMAP_FLAME = 11
COLORMAP_BROWNSCALE = 12
COLORMAP_PILATUS = 13
COLORMAP_AUTUMN = 14
COLORMAP_BONE = 15
COLORMAP_COOL = 16
COLORMAP_COPPER = 17
COLORMAP_GRAY = 18
COLORMAP_HOT = 19
COLORMAP_HSV = 20
COLORMAP_JET = 21
COLORMAP_PINK = 22
COLORMAP_SPECTRAL = 23
COLORMAP_SPRING = 24
COLORMAP_SUMMER = 25
COLORMAP_WINTER = 26
COLORMAP_GIST_EARTH = 27
COLORMAP_GIST_HEAT = 28
COLORMAP_GIST_NCAR = 29
COLORMAP_GIST_RAINBOW = 30
COLORMAP_GIST_STERN = 31
COLORMAP_AFMHOT = 32
COLORMAP_BRG = 33
COLORMAP_BWR = 34
COLORMAP_COOLWARM = 35
COLORMAP_CMRMAP = 36
COLORMAP_CUBEHELIX = 37
COLORMAP_GNUPLOT = 38
COLORMAP_GNUPLOT2 = 39
COLORMAP_OCEAN = 40
COLORMAP_RAINBOW = 41
COLORMAP_SEISMIC = 42
COLORMAP_TERRAIN = 43

There is no limitation to define other colormaps ...

[tbreloff]

👍 Lots of nice options! Two questions:

• how can I define my own colormap to be used in calls to GR? (i.e. unnamed... the user passes a list of colors that should be interpolated between)
• is it possible for me to query the color lists which generate the GR color maps? could they be included somehow in the work in progress ColorMaps.jl?

By the way... I'm starting to use GR more and more... it's really nice (and fast!) I can't wait for it to be fully supported

[jheinen]

You can set (setcolorrep) and inquire (inqcolor) single color entries:

for ci in 1000:1255
   r = g = b = (ci - 1000) / 255.0
  setcolorrep(ci, r, g, b)
  rgb = inqcolor(ci)
  println(uint32(rgb))
end

May be I should provide a more convenient way (in GR).

[jheinen]

I tried some things in 95e6847, but the (retrieved 100) color values did not produce nice results. I must have missed something ...

if haskey(d, :color_palette)
  ci = 1000
  for cv in d[:color_palette]
    GR.setcolorrep(ci, cv.r, cv.g, cv.b)
    ci += 1
  end
end

[tbreloff]

No that's not right. If you want to push up what you have (with that section commented out) I can help fix it.

On Sun, May 8, 2016 at 5:03 AM, Josef Heinen notifications@github.com wrote:

I tried some things in 95e6847 https://github.com/tbreloff/Plots.jl/commit/95e6847cfd3f56b5f239073e50c35b8b802a42a2, but the (retrieved 100) color values did not produce nice results. I must have missed something ...

if haskey(d, :color_palette) ci = 1000 for cv in d[:color_palette] GR.setcolorrep(ci, cv.r, cv.g, cv.b) ci += 1 end end

— You are receiving this because you were mentioned. Reply to this email directly or view it on GitHub https://github.com/tbreloff/Plots.jl/issues/225#issuecomment-217704658

[tbreloff]

It seems like there are 3 outstanding issues here:

• [ ] bug plotting scatter after heatmap (scatter draws to the colorbar)
• [ ] can we turn interpolation off for heatmaps? (Or toggle it somehow)
• [ ] using drawimage to support the image type natively

[tbreloff]

I think this is all working now