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Abraham_Martin
Known Participant
February 12, 2010
Question

How can I see the alpha channel in the channels palette?

  • February 12, 2010
  • 1 reply
  • 5592 views

Hello, mi format plugin loads a rgba image. I see it with transparency, that's ok, but when I go to the channels tab I only see 4 items (RGB, Red, Green and Blue).

How can I see the alpha channel of my file in the channel tab?

Thanks!

This topic has been closed for replies.

1 reply

Chris Cox
Chris Cox
Legend
February 12, 2010

Alpha channels are always shown in the channels palette.

Are you confusing transparency(a strict subset tied to the color of each layer) with alpha channels (general use, the superset).

A
Abraham_MartinAuthor
Known Participant
February 15, 2010

Probably I'm confusing transparency and alpha.

I set the gFormatRecord->planes = 4; (rgba), and fill the gFormatRecord->data with my buffers, but when I open an image in photoshop y get this:

The alpha channel is applied to the rgb channels ok, but the "Alpha 1" channel is black!

I set gFormatRecord->depth = 32 and  gFormatRecord->imageMode = plugInModeRGB48 (RGB96 don't work with 32bit depth images (give me an error), I don't know why, but it is another problem).

Furthermore:

gFormatRecord->transparencyPlane = -1;

gFormatRecord->transparencyMatting = 0;
gFormatRecord->loPlane = 0;
gFormatRecord->hiPlane = 3;

Can I see the alpha channel to modify it and change the visibility of the rgb channels in consequence?

Chris Cox
Chris Cox
Legend
February 16, 2010

Yes, you told Photoshop to open an alpha channel, but never told Photoshop that the extra channel was supposed to be transparency (or how you may have matted the data).

>   gFormatRecord->transparencyPlane = -1;

That means you have no transparency.

You are seeing the alpha channel in the channels palette.

And I'm not sure how you're getting transparency when you told Photoshop you have no transparency....

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