how can I set the resolution of an animation saved as mp4 movie with "matplotlib.animation" module?
On the web I only found examples using "animation.FuncAnimation". For example the nice tutorial from http://jakevdp.github.com/blog/2012/08/18/matplotlib-animation-tutorial/ used:
anim = animation.FuncAnimation(fig, animate, init_func=init,
frames=200, interval=20, blit=True)
anim.save('basic_animation.mp4', fps=30, extra_args=['-vcodec', 'libx264'])
From the matplotlib.animation module reference I found the "animation.Animation.save" method providing a "dpi"-argument, but I don't know how to apply this function properly
matplotlib.animation.Animation.save(filename, writer=None, fps=None, dpi=None, codec=None, bitrate=None, extra_args=None, metadata=None, extra_anim=None)
A small example code may be helpful.
Many thanks.
Johannes
PS: By the way, how can you insert Python-code with sytax-highlighting?
You can control the resolution in a round-about way. The resolution, figure size, and dpi are not all independent, if you know two of them, then the third is fixed.
You can set the dpi in the save argument, and before you save it, set the size of the figure with
fig.set_size_inches(w_in_inches, h_in_inches, True).
Your resolution is then dpi * w_in_inches X dpi * h_in_inches.
dpi = 100
writer = animation.writers['ffmpeg'](fps=30)
ani.save('test.mp4',writer=writer,dpi=dpi)
You may need do upgrade to a newer version of mpl (debian is great because it is so conservative and awful because it is so conservative) from source.
bitrate is the parameter used to specify the quality of a movie. The higher the value you set it to, the higher the quality of the movie will be.
Related
This is more of a feature request. I am easily able to generate the PNG by calling toDataURL on the returned canvas. But the quality of the image is rather blurry/poor. I did some googling & found out that by default it just returns an image at 96 dpi. And there doesnt seem to be a standard way of improving this. Also the toDataURLHD is experimental and does not work any ways.
Is there any way html2canvas can return an image at a higher resolution? Or even if it can provide a way to get the DOM being rendered, I can use some library that uses the DOM (with all the computed styles applied to it) and then generate whatever image I want.
I am unable to comment so writing answer. #shiv probably you should look the quesiton setting canvas toDataURL jpg quality
I am trying to modify the default I-beam cursor image. I'm using [[[NSCursor IBeamCursor] image] representations], passing each one through a CIFilter and adding it to a new image. However, the resulting cursor looks as though it is rendering the low-resolution images.
The High Resolution Guidelines say:
For custom cursors, you can pass a multirepresentation TIFF to the NSCursor class method initWithImage:hotSpot:.
So I would expect this to work. Additionally, if I get the -TIFFRepresentation of the original image and my modified image, and write them to disk, they both look like multi-page TIFF files with the same size images. What could I be doing wrong?
I have a somewhat-temporary solution: manually call -setSize: on each image representation, dividing the pixel height and width by the screen's scale factor. However, this technique doesn't seem like it will work ideally with multiple screens.
You're right on. I've been debugging this all day and I'm pretty sure I've got it nailed. I'm not doing exactly the same thing you are (my images are loaded from a file) but the end result is exactly the same.
The trick is to set the first representation of the multi-representation image to the non-retina size. If you are loading your cursors from an image file, you must take this extra step to adjust the size of the representations to match. It doesn't work 'out-of-the-box' as you would expect.
I've tested this on a machine with two monitors and dragging the window from the retina display to the non-retina display acts as it should, displaying the high/low resolution images for the cursor.
I had a similar problem a while ago: I had my cursor in a PDF, and it always drew as if it was a pixel image at 1:1 size, blown up. There's a solution to that in NSCursor: Using high-resolution cursors with cursor zoom (or retina).
Maybe someone can use that technique to solve this problem? My guess is creating an image with the same size but a different CTM marks it as the same size but Retina. What #jtbrandes is doing probably marks it as a different size and non-Retina. So you're effectively losing the scale factor information. If you create an image with a CTM in the hints, maybe you can draw the filtered images into it and it'll be detected right.
This is very strange.
I would like to show in my swf movie all the icons (jpg/png) I've imported as they are.
I've set the JPG quality 100%, I've tried the PNG settings without quality lost, I've unchecked the "Allow smooth" setting.
But as soon as the movie have quality=high all the icons are smoothed/breaked and do not looks like the original ones ( http://www.emagi.it/icon/icon_high.html ).
Instead, setting quality=low let show the icons as they are!
( http://www.emagi.it/icon/icon_low.html ).
Of course, I need the movie to be quality=high, since there will be some other stuff on it!
So, setting the quality=low is not the solution!
Thank you very much.
You need to check two things:
Make sure the icons' coordinates are not floating point numbers. i.e. they should be exactly "10", not "10.2".
Make sure the instances on the stage have the exact same dimensions as the icons in the library. i.e. if they resolution is 16x16, make sure they are not 16.1x15.8 on stage.
With quality=low Flash is going to round the coordinates to the nearest pixel, which is why the icons look right in this mode.
I am attempting to use RMagick to convert an SVG to a PNG of a different size.
When I read in the SVG with Magick::Image.read('drawing.svg') and write it out to drawing.png (the equivalent of just running convert drawing.svg drawing.png from the command line), the size is 744x1052.
Let's suppose I want the PNG to be twice as large as it is by default. You can't just read it in, resize it, then write it out, as that first rasterizes the SVG and then scales that image to be twice as large, losing quality and the entire benefit of using a vector graphic in the first place. So instead, if I understand correctly, you're supposed to set the image's density upon read.
image = Magick::Image.read('drawing.svg'){self.density = 144}.first
But image.density still reports the density as "72x72", and if I write out the image it has the same size as before, 744x1052. It doesn't seem to matter how I specify the density upon read. With 144, "144", 144.0, "144.0", "144x144", and "144.0x144.0", it always comes back "72x72".
Running convert -density 144 drawing.svg drawing.png from the command line works as expected and generates a PNG that's twice as large as before, 2104x1488.
I'm using OS X 10.6.7, ImageMagick 6.7.0-0 (installed via MacPorts), RMagick 2.13.1, and Ruby 1.9.2p180. When I put my code into the context of a little Sinatra webapp on Heroku, it has the same incorrect behavior, so the issue does not seem to lie with OS X or MacPorts.
Density is about resolution (i.e. dots per inch), not the rendered size. From the fine manual:
The vertical and horizontal resolution in pixels of the image. The default is "72x72".
I think you're looking for resize or resize!:
Changes the size of the receiver to the specified dimensions.
You can specify the new size in two ways. Either specify the new width and height explicitly, or specify a scale factor, a number that represents the percentage change.
So this will work:
Magick::Image.read('drawing.svg').first.resize(2).write('drawing.png')
Or this:
img = Magick::Image.read('drawing.svg').first
img.resize!(2)
img.write('drawing.png')
I don't know why convert behaves differently than the library, there could be other default settings in play that have different defaults in the library or maybe -density does more than set the density.
If resize isn't doing the trick for you (and, based on your comments, it is happening too late to be of use), you can try setting the size parameter in the block:
img = Magick::Image.read('drawing.svg'){ |opts| opts.size = '2104x1488' }.first
Of course, you have to know how big the SVG is before hand. You're supposed to be able to specify things like 200%x200% for the geometry but read always ignores the flag on the Magick::Geometry when I try it.
I am using OGRE to make a re-rendering of the film, which has a wide aspect ratio (around 1.85). The OGRE dialog seems to be showing the standard full screen resolution by default (800/600, 1024/768, etc.), but those obviously have aspect ratios of 1.333 or around that. But as long as I am not running full screen mode, why should I be restricted to these screen sizes only?
I can definitely change the viewport size, but that would make it difficult for me to generate the video later.
Any idea?
There are no any restrictions for using non standard (4:3) aspect ratio screen resolution in Ogre. Default OGRE configuration window just show list of defaults resolution.
But if you need other screen side you should create it from the code directly depending on the dimensions of your input video.