Bugs with the Alpha feature?

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Bugs with the Alpha feature?

Hi everyone,

When I use the alpha feature to make a portion of an object transparent, the alpha feature seems to temporarily be successful.

However, as soon as I play the slideshow, the images that I edit with Alpha revert back to their original state, and are no longer transparent!

I've tried using the Alpha feature on a number of images, and all of them have the same result; transparent as I work on the presentation and non-transparent when I play the presentation.

Does anyone else have this problem?

Mac Pro, OS X Yosemite (10.10.3)

Posted on Aug 18, 2015 11:27 PM

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Answer 1

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Gary Scotland

Level 7

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Aug 19, 2015 2:47 AM in response to b_ellie_b

My guess is you used the Alpha tool to sample a number of colours together. Alpha channel works best using a strong single colour.

Test this by dragging the test image below onto a Keynote slide and click and drag the Alpha tool over one of the colour test patches to create a cut out to show the slide background.

I took a photo of a green storage box with my iPads inbuilt camera, displayed the green image on the screen, took a photo of the iPad and placed that in Keynote, then used the Alpha tool on the green screen image:

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Answer 2

b_ellie_b Author

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Aug 21, 2015 9:27 AM in response to Gary Scotland

So sorry for the late response, and thank you so much for responding!

I dragged the image into a keynote slide and used the Alpha feature on the Magenta color:

However, when I play the presentation, again the same thing happens; it reverts back to the original color:

My previous examples were also solid colors; the phone background was almost solid black except for some shine.

Do you have any other suggestions/ideas? Greatly appreciated!! 🙂

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Answer 3

b_ellie_b Author

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Aug 21, 2015 9:39 AM in response to b_ellie_b

Also, what's really strange is that when I change the style of the photo, for example, add a border or reflection, the alpha feature works when I play the slideshow.

This time I remove the dark blue color with Alpha:

(in edit mode) (in presentation mode--it works!)

However, when I select "no border," which is what I greatly prefer, the presentation plays the image before alpha:

(in edit mode) (presentation mode---reverts back!!)

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Answer 4

Aug 22, 2015 5:16 AM in response to b_ellie_b

After you posted your last findings, I checked some of my previous presentations where I used the alpha tool. I discovered that either a crop, border or some other attribute was added to the images. As you discovered, when I removed all the attributes, the alpha did not work in play mode.

As a workaround, I applied a reflection to the image with a 0% opacity so that the reflection would not show.

You could set this as a custom style in the inspector to work as a one click effect.

Well done for proving my workflow was mistaken.

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Answer 5

b_ellie_b Author

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Aug 23, 2015 7:22 PM in response to Gary Scotland

Thank you very much!! This is a fantastic workaround!

Hopefully Apple will fix this strange bug in an update, but in the mean time I will definitely apply your workaround!

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