Can I use two backends in two filters?

[SSShooter]

I want to do a histogram equalization in a filter which processes the imageData, on the other hand I have a filter use a fragment shader.

But it seem use webgl backend by default. Can I use two backends at the same time?

[asturur]

No you can't use 2 backends, at time, you have to choose one.
What does it stops you to write both filter in the same way?

[asturur]

it seems to me this is just a convolution or colorMatrix filters as we have implemented in fabricJS.

https://github.com/fabricjs/fabric.js/blob/master/src/filters/ColorMatrix.ts
https://github.com/fabricjs/fabric.js/blob/master/src/filters/Convolute.ts

With one of those 2 you can implement that exact kernel
Please take your time to understand the difference between a color matrix and a convolution, once you have a filter setup passing a different image is quite easy you can try easily different combinations

[SSShooter]

Thanks for your information! It's really helpful! 🤩
I thought I can't get pixel around a specific pixel, till I found this.

[asturur]

not sure why the histogram requires nearby pixels, but let me know how it goes.
The convolute filter can be used right away with different matrices you can pass in, and if you need more matrices one after the other you can apply many times the convolute filter

[SSShooter]

oh, I mean convolution requires nearby pixels. histogram eq, it seems, doesn't need them.
I struggle finding a way to convert this to a shader version.

[asturur]

maybe here you can take some info
https://jsfiddle.net/greggman/9amgpndt/