New node: Blur

[calvintvu]

Closes #995

Implements both gaussian and box blurs under raster category

Screen.Recording.mp4

[calvintvu]

Typo in commit message

[Keavon]

I'll try to review this tomorrow.

[TrueDoctor]

Is there a specific reason why you chose to convert this to an image data type first instead of using or inbuilt one? Also @Keavon should blur happen in srgb or linear? They should give different results, so we have to think about which one is correct / what is compatible with other tools

[TrueDoctor]

It also looks like the current implementation quantizes the values to 8 bit which is most likely not what we want. We should also take SIMD friendliness into account here and potentially try to re-enable that target flag and hope that the chrome bug from two years ago has been fixed

[Keavon]

We should have both linear and gamma, with linear as default. https://www.youtube.com/watch?v=LKnqECcg6Gw

[calvintvu]

I've updated it to convert from linear/nonlinear before/after blurring using the functions from graphene_core::raster::Channel and changed from u8 values to f32

[Keavon]

Thanks. In the future, could you please add your followup work as additional commits instead of amending the original commit, so it's possible to compare them?

[calvintvu]

Yes ill keep that in mind

[Keavon]

A couple code review notes before I do a proper code review:

• You're repeating a whole lot of code by doing X then Y without reusing the logic, please do a self-review pass keeping DRY in mind
• Please replace whole-number decimals so they end in a decimal point (.) instead of point-zero (.0), per our style guide
• Run cargo clippy

[Keavon]

I pushed some code review improvements. We still will need you to remove usage of the image crate which you shouldn't need to be doing. Once you do that, please use our existing Color data type's linear/gamma conversion functions. Then please test that a solid red and green has a black border when gamma is active, rather than yellow as with linear.

• Expected with gamma
  
• Expected with linear
  

[Keavon]

Hi @calvintvu, just checking in to see if this is something you're still interested in finishing. Hope to hear from you! Thanks 😄

[calvintvu]

Hi @calvintvu, just checking in to see if this is something you're still interested in finishing. Hope to hear from you! Thanks 😄

Hey @Keavon yeah I can take a look and implement the changes, just busy with some other things at the moment

[calvintvu]

I removed the use of theimage crate and switched the conversion functions to the ones in color.rs (to_linear_srgb and to_gamma_srgb). The linear version has a yellow bar as expected but the gamma verson doesn't seem to have the black bar and I'm not sure how to fix that. Thanks

[Keavon]

!build

[github-actions]

📦 Build Complete for ca98d59
https://e9f90a6f.graphite.pages.dev

[Keavon]

• I believe in your implementation, "Gamma" is actually linear, and linear is actually double linear.
• I also noticed the checkbox for "Box Blur" is backwards.

[Keavon]

Here is a test file you can work with:

blur-test.graphite.txt

[calvintvu]

Ok fixed box blur option and the colors seem to match up better

[Keavon]

!build

[github-actions]

📦 Build Complete for a8b3a0e
https://13f892af.graphite.pages.dev

[Keavon]

It's looking like we need to either premultiply or not premultiply the alpha (the opposite of what's currently being done) to avoid dark areas around the blurred rectangle edges when we have a transparent instead of a white background. We should have functions to premult and unpremult available in the Color method.

[calvintvu]

Got these results after alpha premult/unpremult