kimikage / colorblendmodes.jl Goto Github PK

If both CompositeOperation and BlendMode (i.e., mode and op keyword arguments) are specified, (in-place) blending is performed first and then compositing is applied.
https://drafts.fxtf.org/compositing-1/#generalformula

However, the most conbinations ignore the necessary blending.

At present, the compositing operations have been verified only with the PNG images for the documents. Strictly speaking, the images contain numerical errors, so additional tests are needed.

Hello,

I haven't dug too much into internals, but I'm wondering how hard it would be to write a 3-arg inplace blend! function that the allocating blend uses. I'm mainly looking to blend videos, so reusing the memory from one frame to the next is my goal.

This example might demonstrate what I'm thinking of (where v and v2 are equal lengths, of something like Vector{Matrix{RGB{N0f8}}}):

"allocates only a single frame"
function blendem(v, v2, mode=BlendHardLight)
    img = similar(v[1])
    for i in eachindex(v)
        blend!.(img, v[i], v2[i], mode=mode) # reuses `img`
        save("$i.jpeg", img)
    end
end

"allocates length(v) number of frames"
function blendem2(v, v2, mode=BlendHardLight)
    for i in eachindex(v)
        img = blend.(v[i], v2[i], mode=mode)
        save("$i.jpeg", img)
    end
end

There might be a way to do this without having to change this package, I'm not sure. Does this make any sense (ie will it cut down on allocations?)

The hue values of grays in HSV etc. is meaningless. The gray hues should be ignored.

julia> blend(HSV(0,0,0), HSV(100,1,0), opacity=0.5)
HSV{Float32}(50.0f0,0.5f0,0.0f0)  # actual
HSV{Float32}(100.0f0,0.5f0,0.0f0) # expected

It's not a big deal that this package is in a personal repository, but I'm a little concerned about its lack of popularity. 😭

I still have some plans for changing this package, but I don't think we have a problem committing them under the organization. Rather, I think the problem is the dependency chain in the JuliaImages ecosystem. For now, this package is "isolated", though.

Although the transferring to organization is not an urgent issue, I think it's one to consider if we want to reorganize the repositories of ColorTypes, Colors and ColorVectorSpace.

cc: @timholy, @johnnychen94

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• Add tests for Gray (PR #16)
• Add tests for blending RGB and Gray (PR #17)
• Add support for Lab and Luv
  • multiply, screen, overlay, hard-light, soft-light
  • hue, saturation, color, luminosity (PR #19)
• Add partial support for HSV, HSL and HSI (PR #20)
  • hue, saturation, color, luminosity

Currently, only opaque Colors are supported for the backdrop color.

The alpha composition is a type of operations on transparent colors. Especially if the backdrop is an opaque color, it cannot represent the transparent result. However, I do not want to promote the backdrop from Color to TransparentColor for the sake of consistency.

However, for some operations, if the backdrop is opaque, the result will always be opaque as well. Currently, only the default CompositeSourceOver supports the opaque backsdrop.

julia> CompositeSourceOver(RGB(0), RGB(0)) # the default op
RGB{N0f8}(0.0,0.0,0.0)

julia> CompositeDestination(RGB(0), RGB(0))
ERROR: MethodError: no method matching

julia> CompositeDestinationOver(RGB(0), RGB(0))
ERROR: MethodError: no method matching

julia> CompositeSourceAtop(RGB(0), RGB(0))
ERROR: MethodError: no method matching

julia> CompositeLighter(RGB(0), RGB(0)) # The spec. of "Lighter" is unclear, though.
ERROR: MethodError: no method matching

While opaque backdrop support is not so useful for the two-color compositing, they can be useful in the future when supporting the compositing of three or more colors .

cf. https://drafts.fxtf.org/compositing-1/#blendingnonseparable

One approach is to add PMAColor and PMColorA types.