#Python color palette from image code#

In addition to being used as a regular image storage, the way of assigning colors to different elements of a two-dimensional array can give us a sensory understanding of the spatial layout of the data, similar to the way of heat map visualization. A pseudo-colored image has a single channel, (i.e. R=np.zeros(ar.size*3, dtype=np.uint8).reshape(rows,cols,3)Ĭalling method: pic_arr=voccm.toRGBarray(label,21) G = bitor(g, bitshift(bitget(idx,1),7 - j)) ī = bitor(b, bitshift(bitget(idx,2),7 - j)) R = bitor(r, bitshift(bitget(idx,0),7 - j)) np.zeros default data type is float and usally color map element is float number that less than 1 Ĭmap=np.zeros(N*3, dtype=np.uint8).reshape(N,3) # bitget bitshift bitor zeros is all in matlab internal functionĭef bitshift(num,i): #left shift，if i <0 ,then same as left_shift(num,-i)

#Python color palette from image code#

The following code is used to generate a color map (converted from the code VOCdevkit/VOCcode/VOClabelcolormap.m in the VOC data set) import numpy as np Its properties are: Color.rgb - The color represented as a namedtuple of RGB from 0 to 255, e.g. The function will return a list of numberofcolors Color objects. Also, I will assume, that the palette is known before, and that all colors in the existing RGB image are exclusively from that palette. image may be either a path to a file, a file-like object, or a Pillow Image object.

So, make sure to have your input images not containing more than 256 different colors. Im = omarray(np.uint8(cm.gist_earth(label)*255)) Please keep in mind, that Pillow only allows storing 256 different colors in some color palette, cf. To learn more about the color conversion in Python you can check 5th step of the above article: Working with color names and color values. The image below shows some of the colors: 2. #The color map of gist_earth is applied in the sample code We are going to build different color palettes and different conversion techniques. Label = omarray(label_im, mode='P')Īpply color map #Directly convert to a three-dimensional matrix with RGB information Transfer the VOC color palette to an output mask for visualization. #return an Image object，call its' save('out.png') functioin to save as image file The following python code directly applies the palette of a semantically segmented picture in the VOC data set to the image represented by a two-dimensional matrix #label_im is a numpy array of 1 x height x width The value of each element of the two-dimensional matrix specifies a color, so it can be displayed in color. There is the concept of a colored version in the picture.