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cinemino

Feather Texturing

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Please do a google search for "Straight alpha" , "Pre Multiplied Alpha"

, "Photoshop". etc

Most info in this thread is simply misleading because of not understanding

how the two different alpha types work.

Just adding a black or whit background is not the cure.

As a hint, PS does not default produce Straight Alphas, you need to know

how to produce it yourself. How that is done depends on what kind of

image you want to export for use in a 3D app such as Cinema.

Cheers

Lennart

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"Most info in this thread is simply misleading because of not understanding

how the two different alpha types work."

I disagree. The info in this thread is helping cinemino work out how to get the result he needs. rolleyes.gif

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"I disagree. The info in this thread is helping cinemino work out how to get the result he needs"

Possibly , but there is so far not a single answer that will make it work as it should.

There is a reason for straight alphas. not understanding it and how to produce it will only lead to further confusion

as of why different kinds of fringing occurs.

Cheers

Lennart

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  • Well i can save every kind of image by photoshop so if you tell me the better way is save a TIF becouse it is better i save a TIF, if you advise me to save in PNG i'll do.

    What is the easy way? Create just an image like PNG with transparent background? or create JPG color and JPG for Alpha channel?

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    Is it something like this that you're after? This was just a quickie so it could use some work but I think you'll get the idea. Seems to be some dispute in this thread as to the correct way to go about this, so I shall call this 'just one way of skinning a cat'.

    Cheers

    Karl

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  • Fantastic! Amazing! Thank you so much!

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    "Is it something like this that you're after? This was just a quickie so it could use some work but I think you'll get the idea. Seems to be some dispute in this thread as to the correct way to go about this, so I shall call this 'just one way of skinning a cat'.

    Cheers Karl"

    Karl, no dispute in any way. It least is of coarse not my intention.

    And, for sure, several ways to skin a cat very much applies here. :)

    I felt pointing out that what kind of alpha does what should be seen as

    a hint to learn about premulti- and straight alphas whereabouts.

    They are different for a reason.

    Please let me show a simple comparison in the attached pictures.

    (I hope they show, I've never put anything up here afair..)

    My straight alpha attempts are pretty coarse but should at least tell

    how a premulti alpha can cutout parts the wrong way.

    Straight alphas can keep the pixel info better.

    Please compare the upper part of the feather.

    (The lower part could still have some minutes of added work).

    Cheers

    Lennart

    post-1457-1237303464_thumb.jpg

    post-1457-1237303491_thumb.jpg

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    It's OK, dispute (as long as it's polite) is a useful learning resource. Your examples clearly illustrate the differences. Are these examples straight from C4D checking and unchecking the premultiply option in the material alpha channel? I'm assuming this isn't a multi-pass, comp'd in post kind of premultiply exercise.

    Cheers

    Karl

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    The renders are right out of Cinema.

    Since my chops is far better in AE than in PS, I put the Feather

    in AE and extracted a initial alpha by unmult (by Knoll). Used

    Curve to enhance it somewhat.

    This is the alpha, used as a separate file in Cinema.

    Then ,still in AE, took the feather picture, duplicate it and

    expanded/blurred/copied the duplicate -under- the original pict.

    Cut the original pict by the made alpha.

    Now the feather picture "bleeds" outside its boundaries

    with the (hopefully correct colors).

    This is the picture used in the color channel of Cinema.

    An alternive "quick fix" is to do as you did, but have the

    alpha picture ie four times in a Layer Shader.

    Having the layers set to (down to up)

    Normal,Screen,Overlay, Lighten.(Or what look best)

    This gives a -similar- result, not as detailed and possible not

    suited for animation (will most likely flicker).

    Cheers

    Lennart

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