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Subject: Creating alpha from image


Chrisdmd ( ) posted Wed, 14 May 2008 at 12:52 PM · edited Thu, 26 December 2024 at 9:35 PM

I have used PhotoShop for mostly basic stuff but now I am trying to create an alpha picture from a drawing I made in Photoshop. my question is how do i convert my picture to a black and white alpha?

Sorry for such a newbie question


thundering1 ( ) posted Thu, 15 May 2008 at 6:44 AM

Post the image (or if it's a 4k square, a smaller version of it) - MUCH easier to explain after seeing what you're working on.

But, in the most general explanation, you make a black and white image jut like you said - white shows what you want to be seen, and black "hides" what you don't want to be seen.

Hope this helps-
-Lew ;-)


Chrisdmd ( ) posted Thu, 15 May 2008 at 11:15 AM

Ok I understand that but I made a simple drawing of a house. How do I create an alpha image to use in a 3D software app? Do I just use the magic wand and select everything but the house and make it black. The go back and use the magic wand to select the house and make it white. Then save image (tiff for example) and then use it in 3D app?

PS_ after I use the magic wand and fill the area with the necessary color, how do I unselect the tool without undoing the operation I just performed?

Thanks


Quest ( ) posted Thu, 15 May 2008 at 5:53 PM

Yes Chrisdmd, that is how it’s done. Once you’ve selected the background around the house and made it black (transparent) just hold down the “Shift” and “Ctrl” keys together and press the “I” key to invert the selection then make that white (opaque or visible). You then save that image to whatever format your 3D program uses (it could be any of several formats) and use that black/white image as the alpha file. It’s usually used in conjunction with the original image thereby being the same size and showing through only the house of the original picture without its surroundings. To unselect you simply press “Ctrl” + “D”.

Quest


Chrisdmd ( ) posted Thu, 15 May 2008 at 6:02 PM

Thanks Quest...much appreciated!


thundering1 ( ) posted Fri, 16 May 2008 at 8:17 AM

Ok I understand that but I made a simple drawing of a house. How do I create an alpha image to use in a 3D software app? Do I just use the magic wand and select everything but the house and make it black. The go back and use the magic wand to select the house and make it white. Then save image (tiff for example) and then use it in 3D app?

Or use the Brush and simply paint black to hide, and white to show through. Or use the Lasso, or use Paths, OR the Wand - and yes, Ctr+d to Deselect.

Again, show us the image that you're working on, and we can give you the best or most direct methods - until then, it's complete guesswork on our part - does it require feathering, are there somewhat translucent areas - we have NO clue unless we see it.
-Lew ;-)


Chrisdmd ( ) posted Mon, 19 May 2008 at 10:58 AM

Thank you all for the help. Solved the problem. It wasmy settings in LW that tripped me up.


lvmink ( ) posted Sun, 15 June 2008 at 9:00 PM

Hey Chris-
 your problem sounds like its been solved, but if you want a classic way of creating an alpha channel that is associated with your rgb image- here's the way in Pshop ( I don't know Elements, so I can't tell if appropriate)

if your drawing is already the background layer- use the Magic wand tool to select it
go the the Select menu, Inverse
back to the Select menu- save selection- name it something- look at your channels tab, you will now have an alpha channel for your image


If your drawing is on a layer above the background layer, go to the Select menu
Load selection
back to the Select menu, Inverse
back to the Select menu, Save Selection, name it something...
goto your channels tab, there will be an alpha channel for your image


Chrisdmd ( ) posted Sun, 15 June 2008 at 10:37 PM

Thanks for that tip. actually I like your way the best as I have been having a few problems the other way.

Thanks


Quest ( ) posted Mon, 16 June 2008 at 4:51 PM · edited Mon, 16 June 2008 at 4:53 PM

Anything selected on an image can instantly become an alpha channel quickly and simply by going to the channels pallet and clicking the “Save selection as channel” button at the bottom of the pallet (dark rectangle with white circle in it) and then using this mask to create a grayscale alpha image for a 3D program.

The quality of the alpha channel is dependent on how well you make your selections. By far the most concise way to make a selection is to use the pen tool and painstakingly outline the shape and if need be editing those vector points to refine the selection further but this, by far, is not the fastest way. There are many alternatives to the image selection process many less precise. You need to explore these alternative avenues and use those that work best for you.

Your prior question:

How do I create an alpha image to use in a 3D software app? Do I just use the magic wand and select everything but the house and make it black. The go back and use the magic wand to select the house and make it white. Then save image (tiff for example) and then use it in 3D app?

Where you asking: “how do I create an alpha channel” or “how do I select items in order to create an alpha channel”?

 
 


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