ImageSharp LanczosResampler not working anymore

[feliwir]

Hello everyone,

after updating to rc0003 (from beta0006) the overload of the Resize function that takes a custom IResampler crashes with an LanczosResampler. The line of code is as follows:

...
tgaImage.Mutate(x => x.Resize(384, 384, new LanczosResampler()));
...

Exception:

SixLabors.ImageSharp.ImageProcessingException: "An error occurred when processing the image using ResizeProcessor`1. See the inner exception for more detail."

Inner exception:

ArgumentOutOfRangeException: Specified argument was out of the range of valid values.

Callstack:

    System.ThrowHelper.ThrowArgumentOutOfRangeException()
    System.Span<T>.Slice(int, int)
    SixLabors.ImageSharp.Memory.Buffer2D<T>.GetRowSpan(int)
    SixLabors.ImageSharp.Processing.Processors.Transforms.ResizeKernelMap.CreateKernel(int, int, int)
    SixLabors.ImageSharp.Processing.Processors.Transforms.ResizeKernelMap.BuildKernel<TResampler>(TResampler, int, int)
    SixLabors.ImageSharp.Processing.Processors.Transforms.ResizeKernelMap.PeriodicKernelMap.Initialize<TResampler>(TResampler)
    SixLabors.ImageSharp.Processing.Processors.Transforms.ResizeKernelMap.Calculate<TResampler>(TResampler, int, int, SixLabors.ImageSharp.Memory.MemoryAllocator)
    SixLabors.ImageSharp.Processing.Processors.Transforms.ResizeProcessor<TPixel>.ApplyTransform<TResampler>(TResampler)
    SixLabors.ImageSharp.Processing.Processors.Transforms.ResizeProcessor<TPixel>.SixLabors.ImageSharp.Processing.Processors.Transforms.IResamplingTransformImageProcessor<TPixel>.ApplyTransform<TResampler>(TResampler)
    SixLabors.ImageSharp.Processing.Processors.Transforms.LanczosResampler.ApplyTransform<TPixel>(SixLabors.ImageSharp.Processing.Processors.Transforms.IResamplingTransformImageProcessor<TPixel>)

The exact code used to work before, so i guess that LanczosResampler got some changes maybe?

[JimBobSquarePants]

It’s a struct now. Use KnownResamplers https://docs.sixlabors.com/api/ImageSharp/SixLabors.ImageSharp.Processing.KnownResamplers.html

[feliwir]

We used to use just new LanczosResampler() and now i'm wondering what the default smoothing radius was for that (Lanczos2, Lanczos3 etc.). So pretty much which of the new KnownResamplers mimics the old new LanczosResampler().

Sorry for formulating the question unclear :)

[JimBobSquarePants]

I’d have to check the old binary. Likely 3 though

[JimBobSquarePants]

Are you sure it was beta0006? There's no sign of that class in the assembly, tbh I don't ever remember it.

[feliwir]

We were using Lanczos2Resampler, which also answers my question about the radius we had.
Sorry for the inconvenience, i was very confused

[JimBobSquarePants]

Haha... no worries, Glad you figured it out.

[feliwir]

Okay, fixed this myself already.
For everyone getting the same issues after upgrading:
Use LanczosResampler.Lanczos3 (or some other static member depending on your needs)