I'm using the IPython Notebook on Chrome. I've been trying to display several images in a loop, so that they display one after the other. After no luck with imshow() or set_data() (weird JSON non_serialisable errors, even on uint8 data - same happens when I use Image() on a Numpy array) I wrote the following helper function:
def fshow(im):
imsave('/test.png',im)
display(Image(filename='/test.png'))
which saves the image to a temporary file and then uses Image() to display it. It works beautifully - images pop up one after the other in the output cell, in real time, and I can intersperse them with Print statements if I want to.
But with monochrome images, they show up in the Jet colormap! So I used the following hack to save monochrome images as RGB images with identical colour channels...
def fshow(im):
sh=im.shape
sh=(im.shape[0],im.shape[1],3)
im2=zeros(sh)
im2[:,:,0]=im
im2[:,:,1]=im
im2[:,:,2]=im
imsave('/test.png',im2)
display(Image(filename='/test.png'))
This is, however, a bit of a hack. So, how can I change the colormap which Image uses to display monochrome images?
And as we're here, how do I get Image() to display a Numpy array without complaining that it can't be JSON serialised?
Related
I have a folium.Map that contains custom HTML Popups with clickable URLs. These Popups open when clicking on the polygons of the map. This is a feature that doesn't seem to be possible to achieve using holoviews.
My ideal example of the final application that I want to build with holoviews/geoviews is here with the source code here, but I would like to exchange the main map with my folium Map and plot polygons instead of rasterized points. Now when I would like to create the holoviews.DynamicMap from the folium.Map, holoviews complains (of course) that the data type "map" is not accepted. Is this somehow still possible?
I have found some notebook on GitHub where a holoviews plot in embedded in a folium map using a workaround that writes and reads again HTML, but it seems impossible to embed a folium map into holoviews such that other plots can be updated from this figure using Streams!?
Here is some toy data (from here) for the datasets that I use. For simplicity, let's assume I just had point data instead of polygons:
import folium as fn
def make_map():
m = fm.Map(location=[20.59,78.96], zoom_start=5)
green_p1 = fm.map.FeatureGroup()
green_p1.add_child(
fm.CircleMarker(
[row.Latitude, row.Longitude],
radius=10,
fill=True,
fill_color=fill_color,
fill_opacity=0.7
)
)
map.add_child(green_p1)
return map
If I understand it correctly, this needs to be tweaked now in the fashion that it can passed as the first argument to a holoviews.DynamicMap:
hv.DynamicMap(make_map, streams=my_streams)
where my_streams are some other plots that should be updated with the extent of the folium map.
Is that somehow possible or is my strategy wrong?
I am using detecto model to visualize an image. So basically I am passing an image to this model and it will draw a boundary line accross the object and dislay the visualized image.
from keras.preprocessing.image import load_img
from keras.preprocessing.image import save_img
from keras.preprocessing.image import img_to_array
from detecto import core, utils, visualize
image = utils.read_image('retina_model/4.jpg')
model = core.Model()
labels, boxes, scores = model.predict_top(image)
img=visualize.show_labeled_image(image, boxes,)
Now, I am trying to convert this visualized image into Numpy array. I am using the below line for converting the image into numpy array :
img_array = img_to_array(img)
It is giving the errror :
Unsupported Image Shape
All I want is to display the visualized image which is the output of this model to my website. The plan is to convert the image into numpy array and then save the image by code using the below line :
save_img('image1.jpg', img_array)
So I was planning to download this visualized image (output of this model) so that I can display the downloaded image to my website. If there is some other way to do achieve this then please let me know.
Detecto's documentation says the utils.read_image() is already returning a NumPy array.
But you are passing the return of visualize.show_labeled_image() to Keras' img_to_array(img)
Looking at the Detecto source code of visualize.show_labeled_image(), it has no return type, so it is returning None by default. So I think your problem is you are not passing a valid image to img_to_array(img), but None.
I don't think the call to img_to_array(img) is needed, because you already have the image as a NumPy array. But note that according to Detecto's documentation, utils.read_image() is "Equivalent to using OpenCV’s cv2.imread function and converting from BGR to RGB format" . Make sure that's what you want.
you can visit the official github repo of detecto/visualize.pyto find out the show_labeled_image() function it uses matplotlib to plot the image with bounding boxes you can modify that code in your file to save the plot using plt.save_fig()
I am trying to plot one dependent variable vs two independent variables using matplotlibs heatmap feature, however, I cannot get the image to display correctly. Code and image below.
plt.xticks(np.arange(0, .015, .0015))
plt.yticks(np.arange(-.0005, .0005, .00005))
plt.scatter(Dataset.Gate, Dataset.Bias, c = Dataset.Current)
When I call the same function that uses pandas.plot with the same figsize, I get different sized PNG files. The width is same but the height in pixels changes. I suspect that the length of the x-axis labels changes the height.I have not yet tried directly calling the matplotlib functions.
I have also tried plt.rcParams['figure.figsize'] = (7,4). The problem does not appear to be in how figsize is set. My print_fig_info always produces the desire values.
# Primitive way that confirmed that the figure size does not change
def print_fig_info(label=""):
print(label,str(plt.gcf().get_size_inches()))
def my_plot(df):
global c
print_fig_info("Before plot")
df.plot(kind='bar', figsize=(7,4))
print_fig_info("After plot")
# want to make output files unique
c += 1
plt.savefig("output"+str(c), bbox_inches='tight', dpi='figure')
In your call to savefig you explicitely ask matplotlib to change the figsize to the minimal size that still fits all the elements in via bbox_inches='tight'.
Or in other words, bbox_inches='tight' is especially designed for changing the figure size to the minimum bounding box, and matplotlib is therefore doing what it's being asked for.
Solution: Don't use bbox_inches='tight'.
I have an (n, m) array that I've been visualizing with matplotlib.pyplot.imshow. I'd like to save this data in some type of raster graphics file (e.g. a png) so that:
The colors are the ones shown with imshow
Each element of the underlying array is exactly one pixel in the saved image -- meaning that if the underlying array is (n, m) elements, the image is NxM pixels. (I'm not interested in interpolation='nearest' in imshow.)
There is nothing in the saved image except for the pixels corresponding to the data in the array. (I.e. there's no white space around the edges, axes, etc.)
How can I do this?
I've seen some code that can kind of do this by using interpolation='nearest' and forcing matplotlib to (grudgingly) turn off axes, whitespace, etc. However, there must be some way to do this more directly -- maybe with PIL? After all, I have the underlying data. If I can get an RGB value for each element of the underlying array, then I can save it with PIL. Is there some way to extract the RGB data from imshow? I can write my own code to map the array values to RGB values, but I don't want to reinvent the wheel, since that functionality already exists in matplotlib.
As you already guessed there is no need to create a figure. You basically need three steps. Normalize your data, apply the colormap, save the image. matplotlib provides all the necessary functionality:
import numpy as np
import matplotlib.pyplot as plt
# some data (512x512)
import scipy.misc
data = scipy.misc.lena()
# a colormap and a normalization instance
cmap = plt.cm.jet
norm = plt.Normalize(vmin=data.min(), vmax=data.max())
# map the normalized data to colors
# image is now RGBA (512x512x4)
image = cmap(norm(data))
# save the image
plt.imsave('test.png', image)
While the code above explains the single steps, you can also let imsave do all three steps (similar to imshow):
plt.imsave('test.png', data, cmap=cmap)
Result (test.png):