Color rotation (hue)

[Jean-Patrick Pommier]

Le mercredi 19 mars 2014 10:16:45 UTC+1, Jean-Patrick Pommier a écrit :
>
> Hi,
> I 'd like to modify continuously a pure red image to get an orange, 
> yellow, green, light blue, blue, purple image.
> The idea is to convert a rgb image, to convert it into hsv color space, to 
> modify the hue value then to back convert into rgb color space.
> The problem is that only green and blue can be obtained but no 
> intermediate color:
>
>
> <https://lh4.googleusercontent.com/-s_Acsx0EmRY/UylefCuSGnI/AAAAAAAABsQ/T7pAI2f-D6w/s1600/color_rotation.png>
>
> According to adobe<http://dba.med.sc.edu/price/irf/Adobe_tg/models/hsb.html>, 
> adding a hue equal to 36 should yield a yellow image.
>
> *Here's the code:*
>
> from skimage import io
> from skimage import color
> from scipy import ndimage as nd
> import numpy as np
> from matplotlib import pyplot as plt
> import os
>
> cy55 = io.imread('/home/jeanpat/MFISH/PSI/P07/01/Cy5/P070109C.tif')
>
> zero = np.zeros(cy55.shape,dtype=np.uint8)
> rgb0 = np.dstack([cy55, zero,zero])
>
> hue_rotations = [18, 36,72,90,108]
> images = {}
> images[0] = rgb0
> hsv0 = color.rgb2hsv(rgb0)
> for hue in hue_rotations:
>     hsv = np.copy(hsv0)
>     hsv[:,:,0] = hsv[:,:,0]+ hue
>     rgb = color.hsv2rgb(hsv)
>     images[hue] = rgb
>
> The code to display the images is:

i = 1
plt.figure(num=None, figsize=(15, 5),  facecolor='w', edgecolor='k')
for hue in np.sort(images.keys()):
    plt.subplot(1,6,i,xticks=[],yticks=[])
    plt.title('hue='+str(hue))
    plt.imshow(images[hue])
    i = i +1
plt.show() 

Any greyscaled image should be ok but the image used here is:
>
>
> <https://lh5.googleusercontent.com/-whwEGZWWhIE/UylgLDhf0VI/AAAAAAAABsc/02kl9UCvkAo/s1600/P070109C.tif>
>
>
>
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