Generating color palette for Xmgrace: Difference between revisions
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== HSV colormap == | == HSV colormap == | ||
Use RGB to HSV and reciprocal conversion. Gradients are much easier to derive in HSV format. One can use 'sin' functions instead of linear ones. | Use [http://en.wikipedia.org/wiki/RGB RGB] to [http://en.wikipedia.org/wiki/HSL_and_HSV HSV] and reciprocal conversion. Gradients are much easier to derive in HSV format. One can use 'sin' functions instead of linear ones. | ||
<source lang="py"> | <source lang="py"> |
Revision as of 17:10, 14 October 2011
We provide some simple scripts that generates colormap for Xmgrace. Just copy paste the output in your grace file. Results can be viewed here.
grayscale colormap
<source lang="py">
- !/usr/bin/python
print "@map color 0 to (255, 255, 255), \"white\"" print "@map color 1 to (0, 0, 0), \"black\"" def LinearGray(num):
N=int(255/num) for i in range(1,num): n = str(N*i) print "@map color "+str(i+1)+" to ("+n+','+n+','+n+"), \"gray"+str(i)+"\""
LinearGray(12) </source>
HSV colormap
Use RGB to HSV and reciprocal conversion. Gradients are much easier to derive in HSV format. One can use 'sin' functions instead of linear ones.
<source lang="py">
- !/usr/bin/python
print "@map color 0 to (255, 255, 255), \"white\"" print "@map color 1 to (0, 0, 0), \"black\""
def RGBtoHSV( (R,G,B) , fac = 255.0 ):
R /= fac G /= fac B /= fac M = max(R,G,B) m = min(R,G,B) C = M-m Hp = 0 if not C==0:
if M==R: Hp = ((G-B)/C)%6 elif M==G: Hp = (B-R)/C + 2 elif M==B: Hp = (R-G)/C + 4
H = Hp*60 V = M S = C/V return (H,S,V)
def HSVtoRGB( (H,S,V) ):
C = V*S Hp = H/60 X = C*(1-abs(Hp%2-1)) (R1,G1,B1) = (0,0,0) if 0<=Hp and Hp<1: (R1,G1,B1) = (C,X,0) elif 1<=Hp and Hp<2: (R1,G1,B1) = (X,C,0) elif 2<=Hp and Hp<3: (R1,G1,B1) = (0,C,X) elif 3<=Hp and Hp<4: (R1,G1,B1) = (0,X,C) elif 4<=Hp and Hp<5: (R1,G1,B1) = (X,0,C) elif 5<=Hp and Hp<6: (R1,G1,B1) = (C,0,X) m = V-C (R,G,B) = (R1+m,G1+m,B1+m) return (int(255*R),int(255*G),int(255*B))
def HSVGradient(start,stop,num):
N=int(256/(num-1)) (h1,s1,v1) = start (h2,s2,v2) = stop (hs,ss,vs) = ((h2-h1)/float(num-1),(s2-s1)/float(num-1),(v2-v1)/float(num-1)) for i in range(num):
(h,s,v) = (h1+i*hs,s1+i*ss,v1+i*vs) (r,g,b) = HSVtoRGB( (h,s,v) ) print "@map color "+str(i+2)+" to "+str((r,g,b))+", \"grad"+str(i+1)+"\""
rgbred, rgbgreen, rgbblue = (255,0,0), (0,255,0), (0,0,255) hsvred, hsvgreen, hsvblue = RGBtoHSV(rgbred), RGBtoHSV(rgbgreen), RGBtoHSV(rgbblue)
HSVGradient(hsvred,hsvblue,11)
- HSVGradient((0.0,1.0,1.0),(240.0,1.0,1.0),24)
</source>