Suggestion: Avoid Allocating a New Double Array in PerceptualHash.Hash

[developerjoy]

Hello,

Thank you for the excellent work on CoenM.ImageSharp.ImageHash! It has been very helpful for my project.

I noticed that the PerceptualHash.Hash implementation allocates a new double array every time it is called. While this works well functionally, it can lead to frequent memory allocations, especially when processing a large number of images. This could negatively impact performance due to increased garbage collection.

Would it be possible to optimize the method to reuse the double array or use a more memory-efficient approach?

Thank you for considering this suggestion!

Best regards,
Costa