如何在Bokeh（Python）中处理图像

Question

例如，您可以使用以下代码在matplotlib中绘制图像：

%matplotlib inline
import matplotlib.pyplot as plt
import matplotlib.image as mpimg
img=mpimg.imread('image.png')
plt.imshow(img)

Bokeh（0.10）是否可以这样？

Answer 1

您可以使用ImageURL字形（image_url绘图方法）在本地或从网络加载图像。

from bokeh.plotting import figure, show, output_file

output_file('image.html')

p = figure(x_range=(0,1), y_range=(0,1))
p.image_url(url=['tree.png'], x=0, y=1)
show(p)

一个问题 - 如果您只绘制图像（而不是其他数据），则必须明确设置绘图范围。

以下是文档：

http://bokeh.pydata.org/en/latest/docs/reference/models/glyphs.html#bokeh.models.glyphs.ImageURL

Answer 2

早期的答案很有帮助。但是，我想要一个没有任何附加对象的图像选项。因此，为Bokeh版本0.12.0添加答案并删除所有网格，轴和工具栏。

from bokeh.plotting import figure, curdoc
from bokeh.models import ColumnDataSource, Range1d

bosch_logo = "static/tree.jpg"
logo_src = ColumnDataSource(dict(url = [bosch_logo]))

page_logo = figure(plot_width = 500, plot_height = 500, title="")
page_logo.toolbar.logo = None
page_logo.toolbar_location = None
page_logo.x_range=Range1d(start=0, end=1)
page_logo.y_range=Range1d(start=0, end=1)
page_logo.xaxis.visible = None
page_logo.yaxis.visible = None
page_logo.xgrid.grid_line_color = None
page_logo.ygrid.grid_line_color = None
page_logo.image_url(url='url', x=0.05, y = 0.85, h=0.7, w=0.9, source=logo_src)
page_logo.outline_line_alpha = 0 
curdoc().add_root(page_logo)

Answer 3

使用散景服务运行此示例有点棘手。我建议正确设置工作目录：

server_folder/
     +main.py
     +static/
         +logo.png

..并从目录 ABOVE server_folder

运行bokeh serve命令

bokeh serve server_folder --show

然后这段代码适合我

#main.py file
from bokeh.plotting import figure, curdoc
x_range = (-20,-10) # could be anything - e.g.(0,1)
y_range = (20,30)
p = figure(x_range=x_range, y_range=y_range)
#img_path = 'https://bokeh.pydata.org/en/latest/_static/images/logo.png'
img_path = 'server_folder/static/logo.png'
p.image_url(url=[img_path],x=x_range[0],y=y_range[1],w=x_range[1]-x_range[0],h=y_range[1]-y_range[0])
doc = curdoc()
doc.add_root(p)

Answer 4

另一个选择是将图像显示在div中。：

from bokeh.io import output_notebook, show
from bokeh.models.widgets import Div

output_notebook()
div_image = Div(text="""<img src="https://raw.githubusercontent.com/PokeAPI/sprites/master/sprites/pokemon/7.png" alt="div_image">""", width=150, height=150)
show(div_image)

ImageURL can't get updated dynamically with a callback。但是，使用div可以通过将div_image.text当作常规Python字符串来实现，例如：

from ipywidgets import interact

from bokeh.io import output_notebook, show, push_notebook
from bokeh.models.widgets import Div

output_notebook()
div_image = Div(text="""<img src="https://raw.githubusercontent.com/PokeAPI/sprites/master/sprites/pokemon/1.png" alt="div_image">""", width=100, height=100)

def update(pokemon_number=1):
    div_image.text = """<img src="https://raw.githubusercontent.com/PokeAPI/sprites/master/sprites/pokemon/{}.png" alt="div_image">""".format(pokemon_number)
    push_notebook()

show(div_image, notebook_handle=True)

interact(update, pokemon_number=[1, 4, 7])

当然，图像源也可以指向本地文件。

（在Python 3.7.3和bokeh 1.2.0中测试）