[julia-users] Re: ImageView very slow

[Josef Heinen]

Paul: Would be helpful to see the real data (file) you want to visualize 
and the plot you are expecting.

[julia-users] Re: ImageView very slow

[Josef Heinen]

Using GR (for the image display) should be fast enough:

using TestImages
using GR

img = testimage("cameraman")
intensities = reshape(reshape(float(img.data[:]), 512, 512)

for i in 1:10
tic(); imshow(intensities, colormap=GR.COLORMAP_GRAY); toc() 
end


% julia img.jl 

elapsed time: 1.190862896 seconds

elapsed time: 0.007231715 seconds

elapsed time: 0.013265573 seconds

elapsed time: 0.00677057 seconds

elapsed time: 0.012534283 seconds

elapsed time: 0.010761427 seconds

elapsed time: 0.00731559 seconds

elapsed time: 0.009606974 seconds

elapsed time: 0.007050752 seconds

elapsed time: 0.008927604 seconds

The first call is slower because the window has to be set up.




On Sunday, October 16, 2016 at 6:45:00 PM UTC+2, Paul B. wrote:
>
> Hello, all.  Starting out with Julia.
>
> I need to display some pseudo-color images so I'm playing around with the 
> ImageView package.  It seems to be running very slowly.  Displaying one of 
> the images from TestImages can take nearly a minute:
> img = testimage( "cameraman" )
> Gray Images.Image with:
>   data: 512×512 Array{ColorTypes.Gray{FixedPointNumbers.UFixed{UInt8,8}},2
> }
>   properties:
> colorspace: Gray
> spatialorder:  x y
>
> julia> tic(); ImageView.view( img ); toc();
> elapsed time: 50.552471225 seconds
> Zooming and other interaction with the mouse is similarly sluggish.
>
> I didn't expect this for a 512x512 grayscale image.  I am running Julia 
> version 0.5.1-pre+2 and ImageView is running into some issues with 
> deprecated functionality and namespace conflicts.  However, the above did 
> not generate any warnings at all but still took 50 seconds to display.  
> This is all under Linux.  Any ideas why this is happening or if I could be 
> doing something wrong?
>

Re: [julia-users] Re: ImageView very slow

[Tim Holy]

Yes, it should be pretty responsive now---ImageView doesn't have to go
through a Python layer, so I think it's a bit snappier. It's been a while
since I've used Matlab, but at least when I first compared them ImageView
was considerably better than Matlab for interactive display of movies, etc.
But Tk does have pretty significant limitations; now that the Images
rewrite is largely done I'm planning to rewrite ImageView using Gtk. Not
started yet, though.

On Tue, Oct 25, 2016 at 5:24 PM, Paul B.  wrote:

> Tim, when you say you fixed this, you mean the deprecation warnings?  I'll
> definitely use the new version of Images.  I haven't had a chance yet since
> posting this.  Images and related libraries look great.
>
> The graphics functionality in Julia that deal with bitmaps like ImageView
> and pcolor in PyPlot seem slow.  I'm used to imagesc in MATLAB which can be
> unresponsive for very large images but not quite as sluggish as what I've
> been seeing.  From what little I found, it sounds like a lot of these use
> Tk which is controlled through text commands.  Am I mistaken?  Is there
> something maybe simpler but quicker than ImageView that will display a
> pseudo-color image?  Otherwise I might just bang something up that uses
> Images to save a PNG file then calls an external viewer to display it.
>
>>

Re: [julia-users] Re: ImageView very slow

[Paul B.]

Tim, when you say you fixed this, you mean the deprecation warnings?  I'll 
definitely use the new version of Images.  I haven't had a chance yet since 
posting this.  Images and related libraries look great.

The graphics functionality in Julia that deal with bitmaps like ImageView 
and pcolor in PyPlot seem slow.  I'm used to imagesc in MATLAB which can be 
unresponsive for very large images but not quite as sluggish as what I've 
been seeing.  From what little I found, it sounds like a lot of these use 
Tk which is controlled through text commands.  Am I mistaken?  Is there 
something maybe simpler but quicker than ImageView that will display a 
pseudo-color image?  Otherwise I might just bang something up that uses 
Images to save a PNG file then calls an external viewer to display it.

>

Re: [julia-users] Re: ImageView very slow

[Tim Holy]

Hmm, I fixed this on the images-next branch but forgot to fix it on master.
Will be fixed in https://github.com/timholy/Images.jl/pull/564.

If you're just getting started with Julia & Images, you might want to
consider using the upcoming version of Images. See
https://github.com/timholy/Images.jl/issues/542#issuecomment-254059092.

Best,
--Tim

[julia-users] Re: ImageView very slow

[Páll Haraldsson]

On Sunday, October 16, 2016 at 4:45:00 PM UTC, Paul B. wrote: 

> into some issues with deprecated functionality
>

I think they can make slower, not sure if by this much. 

I see: "fix julia 0.5 deprecations   19 days ago"

Maybe if you update the package this will be ok?