I am trying to make sure that a bunch of different spectrographs I am trying to produce have the same colorbar scale so I can compare them. This is the code I have so far:
for tr in traces:
#fig = tr.spectrogram(log=True)
fig = tr.spectrogram(show=False, log=True)
ax = fig.axes[0]
mappable = ax.collections[0]
plt.colorbar(mappable=mappable, ax=ax)
plt.show()
This is a sample spectrograph I produced with that:
If I wanted the colorbar range to go from 0 to 800 rather than 0 to 120, how could I do that? Thank you.
I've so far looked at the documentation for matplotlib.pyplot.colorbar, but I cannot see if there's a way to do what I am trying.
Related
I have these two functions in my program:
def depict_ph_increase(x,y,color, imobject):
program_print(color)
draw = PIL.ImageDraw.Draw(imobject)
draw.text((x, y),color,(255,255,255))
imobject.save('tmp-out.gif')
im_temp = PIL.Image.open("tmp-out.gif")#.convert2byte()
im_temp = im_temp.resize((930, 340), PIL.Image.ANTIALIAS)
MAP_temp = ImageTk.PhotoImage(im_temp)
map_display_temp = Label(main, image=MAP_temp)
map_display_temp.image = MAP_temp # keep a reference!
map_display_temp.grid(row=4,column=2, columnspan=3)
def read_temp_pixels(temperature_file, rngup, rngdown):
temp_image_object = PIL.Image.open(temperature_file)
(length, width) = get_image_size(temp_image_object)
(rngxleft, rngxright) = rngup
(rngyup,rngydown) = rngdown
print 'the length and width is'
print length, width
hotspots = 5;
for hotspot in range(0,hotspots):
color = "#ffffff"
while color == "#ffffff" or color == "#000000" or color == "#505050" or color == "#969696":
yc = random.randint(rngxleft, rngxright)
xc = random.randint(rngyup,rngydown)
color = convert_RGB_HEX(get_pixel_color(temp_image_object, xc, yc))
depict_ph_increase(xc,yc,color, temp_image_object)
The bottom one calls the top one. Their job is to read in this image:
It then randomly selects a few pixels, grabs their colors, and writes the hex values of the colors on top. But, when it redisplays the image, it gives me this garbage:
Those white numbers up near the upper right corner are the hex values its drawing. Its somehow reading the values from the corrupted image, despite the fact that I don't collect the values until AFTER I actually call the ImageDraw() method. Can someone explain to me why it is corrupting the image?
Some background--the get_pixel_color() function is used several other times in the program and is highly accurate, its just reading the pixel data from the newly corrupted image somehow. Furthermore, I do similar image reading (but not writing) at other points in my code.
If there is anything I can clarify, or any other part of my code you want to see, please let me know. You can also view the program in its entirety at my github here: https://github.com/jrfarah/coral/blob/master/src/realtime.py It should be commit #29.
Other SO questions I have examined, to no avail: Corrupted image is being saved with PIL
Any help would be greatly appreciated!
I fixed the problem by editing this line:
temp_image_object = PIL.Image.open(temperature_file)
to be
temp_image_object = PIL.Image.open(temperature_file).convert('RGB')
I am trying to average the colours in an image, I have come up with the following script (from here):
scrip.rb:
require 'rmagick'
file = "./img.jpg"
img = Magick::Image.read(file).first
color = img.scale(1, 1).pixel_color(0,0)
p [color.red, color.green, color.blue]
img.jpg:
BUT the RGB output is [31829, 30571, 27931].
Questions:
Shouldn't the numbers be in the range of [0-255]?
What am I doing wrong?
What you have there is the red, green, and blue histogram values.
You need to divide by 256 in order to get each RGB value. In this case, the RGB values are:
require 'rmagick'
file = "./img.jpg"
img = Magick::Image.read(file).first
color = img.scale(1, 1).pixel_color(0,0)
p [color.red/256, color.green/256, color.blue/256]
# => [124, 119, 109]
This blog post provides a more thorough explanation on how to analyse images with RMagick.
The reason for the odd output is due to the bit depth. As a previous answer states, "They are stored in a 'quantum depth' of 16-bits." This was an initial assumption, but by looking at previous answers, this makes more sense. In order to properly convert these numbers back to your typically desires [0-255] range, you must divide the values by 256.
Note: You can change the quantum depth during runtime. When reading the file, you should be able to use a block like shown in the following code.
img = Magick::Image.read(file){self.depth = 8}.first
I'm working with some MRI data in Matlab 2014b, but the data is formed of intensity values not RGB. To get around this I use the code below to form a movie out of the MRI frames (I'm working on dynamic data here)
My problem is that the images need to have altered display values for the pixels, as the default only displays between -Inf and Inf, and I need between 0 and 0.25 to get a sensible image out of my data.
Are there any ways to pass that change from the script in to the movie, and then to write to file? I can only seem to do this per image in implay, and I'd like an automated way to edit each image and then store as a frame for a movie..?
%Code for producing movie.
graymap = gray(256);
for i = 1:32
a(:,:,i) = cmunique(Reformed_Data_Colourmap(:,:,i));
end
for i = 1:32
b = im2frame(a(:,:,i),graymap);
a(:,:,1) = ((b.cdata));
image(a(:,:,1))
colormap 'gray'
%The change needs to be here, to display pixel values from 0 to 0.25, to allow for a sensible image from the MR data.
frames(1,i) = getframe;
end
movie(frames)
The solution is provided:
for i = 1:32
b = im2frame(a(:,:,i),graymap);
a(:,:,1) = ((b.cdata));
clims = [0 250];
%image(a(:,:,1),clims)
colormap 'gray'
imagesc(a(:,:,1),clims);
%set('window', [0 400])
frames(1,i) = getframe;
end
clims solves the issue.
I'm trying to use the answers I found in these questions:
How to save a plot into a PDF file without a large margin around
Get rid of the white space around matlab figure's pdf output
External source
to print a matlab plot to pdf without having the white margins included.
However using this code:
function saveTightFigure( h, outfilename, orientation )
% SAVETIGHTFIGURE(H,OUTFILENAME) Saves figure H in file OUTFILENAME without
% the white space around it.
%
% by ``a grad student"
% http://tipstrickshowtos.blogspot.com/2010/08/how-to-get-rid-of-white-margin-in.html
% get the current axes
ax = get(h, 'CurrentAxes');
% make it tight
ti = get(ax,'TightInset');
set(ax,'Position',[ti(1) ti(2) 1-ti(3)-ti(1) 1-ti(4)-ti(2)]);
% adjust the papersize
set(ax,'units','centimeters');
pos = get(ax,'Position');
ti = get(ax,'TightInset');
set(h, 'PaperUnits','centimeters');
set(h, 'PaperSize', [pos(3)+ti(1)+ti(3) pos(4)+ti(2)+ti(4)]);
set(h, 'PaperPositionMode', 'manual');
set(h, 'PaperPosition',[0 0 pos(3)+ti(1)+ti(3) pos(4)+ti(2)+ti(4)]);
% save it
%saveas(h,outfilename);
if( orientation == 1)
orient portrait
else
orient landscape
end
print( '-dpdf', outfilename );
end
Results in this output:
As you can see the 'PaperSize' seems to be set not properly. Any idea of possible fixes?
NOTE
If I change the orientation between landscape and portrait the result is the same, simply the image is chopped in a different way.
However if I save the image with the saveas(h,outfilename); instruction the correct output is produced.
Why is this? And what is the difference between the two saving instructions?
Alltogether the answers you mentioned offer a lot of approaches, but most of them didn't worked for me neither. Most of them screw up your papersize when you want to get the tight inset, the only which worked for me was:
set(axes_handle,'LooseInset',get(axes_handle,'TightInset'));
I finally wrote a function, where I specify the exact height and width of the output figure on paper, and the margin I want (or just set it to zero). Be aware that you also need to pass the axis handle. Maybe this functions works for you also.
function saveFigure( fig_handle, axes_handle, name , height , width , margin)
set(axes_handle,'LooseInset',get(axes_handle,'TightInset'));
set(fig_handle, 'Units','centimeters','PaperUnits','centimeters')
% the last two parameters of 'Position' define the figure size
set(fig_handle,'Position',[-margin -margin width height],...
'PaperPosition',[0 0 width+margin height+margin],...
'PaperSize',[width+margin height+margin],...
'PaperPositionMode','auto',...
'InvertHardcopy', 'on',...
'Renderer','painters'... %recommended if there are no alphamaps
);
saveas(fig_handle,name,'pdf')
end
Edit: if you use painters as renderer saveas and print should produce similar results. For jpegs print is preferable as you can specify the resolution.
I am getting more than ...slightly flustered... at trying to do what should otherwise be a very, very simple task.
I want to use a particular figure, say, figure(3), for doing imagesc. So in the beginning of my code, I always do this:
f3 = figure(3);
a3 = gca;
Then, I get some matrix data, of arbitrary size. Say that I got data of size 231 x 322. Now, I want to tell MATLAB, to perform imagesc(data), but on figure(3).
How do I do that?? imagesc doesnt take figure or axes handles, and this is becoming very, very frustrating... thanks!
imagesc takes a 'parent' parameter. This is indirectly documented via the image function.
For example:
imdata = imread('ngc6543a.jpg');
f = figure;
a1 = subplot(211);
a2 = subplot(212);
image(imdata,'parent',a1);
imagesc(imdata,'parent',a2);