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  1. #1

    Question How is transparency calculated?

    On a black background, a white (#ffffff) rectangle with 50% transparency (Mix) is darker than a 50% white (#808080) rectangle. Shouldn't it look exactly the same?

    Software: Xtreme Pro 5.1

  2. #2
    Join Date
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    Default Re: How is transparency calculated?

    Oh probably. But it is more of an eyeball thing where you know it's the right amount when you see it.

  3. #3
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    Default Re: How is transparency calculated?

    Anyway that is very good question like that precisely :-) Finally the vector graphics based on math so really why it does not exactly the same?

  4. #4

    Default Re: How is transparency calculated?

    Quote Originally Posted by feklee View Post
    On a black background, a white (#ffffff) rectangle with 50% transparency (Mix) is darker than a 50% white (#808080) rectangle. Shouldn't it look exactly the same?

    Software: Xtreme Pro 5.1
    Using X9 here.

    Which white rectangle, using your hex numbers and transparency number, is which?
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  5. #5
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    Default Re: How is transparency calculated?

    To me the one on the right looks darker, Mike. But I sampled both and I was wrong.

    I can confirm Mike's results in DPX9.

  6. #6

    Default Re: How is transparency calculated?

    This is using version 6. I don't have a version before 6 to try.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  7. #7

    Default Re: How is transparency calculated?

    I didn't save my original test case, and lost it (computer crashed). Now I cannot reproduce the issue anymore. It could be that I did something wrong or that there is a strange bug in 5.1 which only manifests itself under certain circumstances.

  8. #8
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    Default Re: How is transparency calculated?

    Time to Upgrade.

    I did a test of various options and did find a 1 point difference in a few of the resultant colors but these may have been rounding off issues.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  9. #9
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    Default Re: How is transparency calculated?

    Quote Originally Posted by feklee View Post
    ]Shouldn't it look exactly the same?[/I]

    Software: Xtreme Pro 5.1
    maybe depends how you do it

    for example, if I type in 808080 in the colour editor to set the second square, I can see a very slight variation, and this may be because when I look at the HSV value it is H-0 S-0% V-50.29%

    if I then reset the HSV to H-0 S-0% V-50% exactly the slight difference disappears [the hex value displayed remains at 808080]
    -------------------------------
    Nothing lasts forever...

  10. #10

    Default Re: How is transparency calculated?

    I set gray scale intensity to 50%, and the result was #808080 for RGB. But the difference to the 100% white 50% transparent object was big, i.e. not just a rounding error.

 

 

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