Cell array of images like Matlab

[Drew Mahedy]

I'm just wondering if there is a way to load several RGB .jpg images into a 4-D array like can be done in MATLAB using cell array. I have the Images package installed but concatenating 2 images in the 3rd or 4th dimension says that 'only two-dimensional images are supported in assert2d' when I try.

[Uwe Fechner]

Could you post code, that reproduces the problem?

[Drew Mahedy]

Here is what the code looks like in MATLAB:

AA = cell( size(trimcoorddir,1), 1 );

figpathdir2 = dir( strrep( figpath2, '\', filesep ) );

fignames2 = {figpathdir2.name};

for i = 1:length(trimcoorddir);

    if all( strcmp( fignames2, trimcoord{i}.filename ) == 0 );

        A = imread( strrep( [figpath, '\', trimcoord{i}.filename], '\', filesep ) );

        AA{i} = rgb2gray( A );

        AA{i} = 255 - medfilt2( AA{i}, [25 25] ) + AA{i};  %Time Consuming!

        AA{i} = imadjust( AA{i}, [0.96 1], [0 1], 1.0 );

        

        imwrite( AA{i}, strrep( [figpath2, '\', trimcoord{i}.filename], '\', filesep ) );

    else

        AA{i} = imread( strrep( [figpath2, '\', trimcoord{i}.filename], '\', filesep ) ); 

    end

end

[Drew Mahedy]

In Julia, if I try and concatenate two images together of type:

Array{ColorTypes.Gray{FixedPointNumbers.UFixed{UInt8,8}},2} via

cat( 3, img, img ),

I get the following error:

Only two-dimensional images are supported

On Wednesday, September 7, 2016 at 7:24:14 PM UTC-7, Uwe Fechner wrote:

[El suisse]

julia version???

julia>versioninfo()

​

[Uwe Fechner]

Sorry, but this is not a complete example that I could run to reproduce the problem.

[Matt Bauman]

I cannot reproduce that error, and I know that the lead author of Images uses stacked image arrays quite frequently.

julia> using TestImages, Images
       src = testimage("mandrill")
       arr = convert(Array{ColorTypes.Gray{FixedPointNumbers.UFixed{UInt8,8}},2}, src)
       cat(3, arr, arr)
512x512x2 Array{ColorTypes.Gray{FixedPointNumbers.UFixed{UInt8,8}},3}:
...

julia>img = Image(arr)
       cat(3, img, img)
Gray Images.Image with:
  data: 512x512x2 Array{ColorTypes.Gray{FixedPointNumbers.UFixed{UInt8,8}},3}
…

Are you doing this in an IJulia notebook?  It may be that the error you're seeing is simply that IJulia doesn't know how to display a stack of images.

On another note, the Julia equivalent to a cell array is an `Any[]` array, which is quite different from concatenating the images together in a higher dimension.  You can even use the Matlab-like `cell( size(trimcoorddir,1) )` to initialize an array that can hold anything like a cell array.

, 

[Tim Holy]

Try putting a semicolon at the end of that line.

Thanks for the bug report! https://github.com/timholy/Images.jl/issues/554

--Tim

On Friday, September 9, 2016 5:18:45 PM CDT Drew Mahedy wrote:
> In Julia, if I try and concatenate two images together of type:
>
> Array{ColorTypes.Gray{FixedPointNumbers.UFixed{UInt8,8}},2} via
>
> cat( 3, img, img ),
>
> I get the following error:
>
> Only two-dimensional images are supported
>