Slow Loading Images

[fdncred]

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• question
• bug report
• feature request

Issue description
Hey @cesarsouza,
I have not looked at the code yet but something strange seems to be going on with Accord.Imaging.Image.FromFile(). Both of my test images are bitonal 200 DPI about 1500W x 1600H.

Quick code

var sw = new Stopwatch();

var inFileName = @"C:\SomePath\To\Image1\07128777.tif";
var inFileName2 = @"C:\SomePath\To\Image2\07128778.tif";
sw.Start();
var inFileBmp = Accord.Imaging.Image.FromFile(inFileName);
sw.Stop();
Console.WriteLine($"Accord.Imaging.Image.FromFile Image 1 in [{sw.ElapsedMilliseconds}].");

sw.Reset();
sw.Start();
var inFileBmp2 = Accord.Imaging.Image.FromFile(inFileName2);
sw.Stop();
Console.WriteLine($"Accord.Imaging.Image.FromFile Image 2 in [{sw.ElapsedMilliseconds}].");

sw.Reset();
sw.Start();
var inFileBmp3 = System.Drawing.Image.FromFile(inFileName);
sw.Stop();
Console.WriteLine($"System.Drawing.Image.FromFile Image 1 in [{sw.ElapsedMilliseconds}].");

sw.Reset();
sw.Start();
var inFileBmp4 = System.Drawing.Image.FromFile(inFileName2);
sw.Stop();
Console.WriteLine($"System.Drawing.Image.FromFile Image 2 in [{sw.ElapsedMilliseconds}].");

Quick code results

Accord.Imaging.Image.FromFile Image 1 in [963] ms.
Accord.Imaging.Image.FromFile Image 2 in [3374] ms.
System.Drawing.Image.FromFile Image 1 in [10] ms.
System.Drawing.Image.FromFile Image 2 in [9] ms.

Any idea why Accord is taking so long to load files (in comparison to System.Drawing.Image)?

BTW - This was in debug with NuGet versions of 3.8.0.0.
I'm using VS2017.
I'm on Windows 10 1709 (Fall Creators Update)

Thanks,
Darren

[fdncred]

I'm guessing the slowdown is because of using Linq/Reflection to find registered decoders. That's really the only recent difference I see.

[cesarsouza]

Hi @fdncred,

Yeah, I guess this is happening because Accord.NET is looking whether there are any available image decoders (classes marked with the FormatDecoderAttribute and implementing the IImageDecoder interface) that could have been used to decode .tif images at every call to the FromFile function.

I guess the best solution would be to update ImageDecoder.FromFile function (and the analogous Audio class as well) to recognize that a particular extension have been successfully decoded (or not) using the internal .NET image class and avoid trying to enumerate all possible image decoders again in case future files have this same extension again.

Regards,
Cesar

[cesarsouza]

Hi @fdncred,

I've uploaded a new pre-release to NuGet, in which this issue should hopefully have been addressed.

Regards,
Cesar