How to darken spectrograms for a figure

[Benjamin Colbert]

I have the attached spectogram created using the code below. I want the signals to be much darker while keeping background as white. How can I do that? I will be getting rid of the amplitude label - that info isn't useful for what I am trying to display.

spec<- spectro(wav, f=f, ovlp=75, zp=16, wl = 1024, collevels=seq(-40,0,0.5), flim=c(.1,.8),palette=reverse.gray.colors.2)

[Jérôme SUEUR]

Dear Benjamin,

The gray palettes, 'reverse.gray.colors.1' and 'reverse.gray.colors.2', are based on the function gray().

The code for 'reverse.gray.colors.1' is 

reverse.gray.colors.1 <- function (x) gray(seq(from = 1^1.7, to = 0, length = x)^(1/1.7))

You could then adapt it to you own needs by changing the scaling factor (here 1.7), for instance setting a lower value should give more importance to high part of the scale, like

reverse.gray.colors.3 <- function (x) gray(seq(from = 1^0.5, to = 0, length = x)^(1/0.5))

For a comparison:

library(seewave)

data(tico)

reverse.gray.colors.3 <- function (x) gray(seq(from = 1^0.5, to = 0, length = x)^(1/0.5))

par(mfrow=c(2,1))

spectro(tico, palette=reverse.gray.colors.1, scale=FALSE)

spectro(tico, palette=reverse.gray.colors.3, scale=FALSE)

Another possibility might to use the function choose_palette() of the package colorspace. This is a nice GUI to play with.

HTH,

Jerome

NB: when posting a request you might say "hello", "thank you" or other kind words, it is always welcome for those who spend time to try to help ;-)

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De: "Benjamin Colbert" <bcol...@umces.edu>
À: "seewave GROUP" <see...@googlegroups.com>
Envoyé: Mardi 17 Janvier 2023 18:14:31
Objet: [seewave] How to darken spectrograms for a figure

I have the attached spectogram created using the code below. I want the signals to be much darker while keeping background as white. How can I do that? I will be getting rid of the amplitude label - that info isn't useful for what I am trying to display.

spec<- spectro(wav, f=f, ovlp=75, zp=16, wl = 1024, collevels=seq(-40,0,0.5), flim=c(.1,.8),palette=reverse.gray.colors.2)

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