How do you save an alpha channel to an image?

I'm trying to experiment with a program I have called Enfuse. It will allow me to load images that have an alpha channel, but when I do that I get an error message. Therefore, I must be doing something wrong when I save the alpha channel.

Can someone explain to me the steps I need to take to do this correctly?

Create a selection with any selection tool, the go to Select > Save Selection.
This converts the selection into an alpha channel.
Now save the file in a format which Enfuse can load (it should be TIFF, PSD or TARGA).

I guess its an issue with Enfuse, because the files saved just fine. I can even see the areas that are blocked out by the alpha channels when I look at them. However, Enfuse is not picking up on it for some reason.

Thanks, I'm closer than I was. LOL

Not sure if this helps, but ...

I also use Enfuse (EnfuseGUI to be exact). If I do a conversion from RAW to 16-bit TIF out of DPP, Enfuse can not use/read/work on the files; however, if I run those files through the CS5 Image Processor function, saving as 16-bit TIFs, those re-converted TIFs do work. The files are not the same, the file sizes differ slightly, so something must be different.

Maxdave

Maxdave,

I know how to use Enfuse, I use it via the LR/Enfuse plug-in and it works just fine in that aspect. What I'm trying to figure out is how to use Enfuse with Alpha Channels applied to the images. Enfuse claims it can read Alpha Channels, but when I load those images into Enfuse it does not work. The advantage of using Alpha Channels (theoretically) is that I can select pixels (dark shadows for example) that I do not want to be considered by giving those pixels a value of zero. That way, Enfuse will not consider those pixel for blending.

I am starting to think that I need to learn more about the line commands to maximize my results.

Thanks for the replies!

Hey T,

There are a couple of things you need to make sure you do to get Enfuse cranking with your alpha channels. First, you need to save your source images in a format that supports alpha channels (TIFF, PNG, TARGA). If you are taking your source images into Photoshop and adding an alpha there, remember to check the appropriate box to tell Photoshop to save the alpha channel! This is sometimes overlooked and can drive one crazy when trying to troubleshoot.

enfuse [Input_image_01] [Input_image_02] [Input_image_N] -o [output_image.extensio​n]

KT-Laptop:dxo6 kirkt$ enfuse-openmp /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​2enfuse.tif /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​7enfuse.tif /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_001​0enfuse.tif -o default.tif
enfuse: info: input image "/Users/kirkt/Desktop/​EnfuseTest/dxo6/_MG_00​02enfuse.tif" does not have an alpha channel;
enfuse: info: assuming all pixels should contribute to the final image
enfuse: info: input image "/Users/kirkt/Desktop/​EnfuseTest/dxo6/_MG_00​07enfuse.tif" does not have an alpha channel;
enfuse: info: assuming all pixels should contribute to the final image
enfuse: info: input image "/Users/kirkt/Desktop/​EnfuseTest/dxo6/_MG_00​10enfuse.tif" does not have an alpha channel;
enfuse: info: assuming all pixels should contribute to the final image
enfuse: info: loading next image: /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​2enfuse.tif 1/1
enfuse: info: loading next image: /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​7enfuse.tif 1/1
enfuse: info: loading next image: /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_001​0enfuse.tif 1/1

KT-Laptop:dxo6 kirkt$ enfuse-openmp /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​2enfuse-alpha.tif /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​7enfuse.tif /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_001​0enfuse.tif -o alphaout.tif
enfuse: warning: /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​2enfuse-alpha.tif: wrong data type 7 for "RichTIFFIPTC"; tag ignored
enfuse: info: input image "/Users/kirkt/Desktop/​EnfuseTest/dxo6/_MG_00​07enfuse.tif" does not have an alpha channel;
enfuse: info: assuming all pixels should contribute to the final image
enfuse: info: input image "/Users/kirkt/Desktop/​EnfuseTest/dxo6/_MG_00​10enfuse.tif" does not have an alpha channel;
enfuse: info: assuming all pixels should contribute to the final image
enfuse: info: loading next image: /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​2enfuse-alpha.tif 1/1
enfuse: info: loading next image: /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_000​7enfuse.tif 1/1
enfuse: info: loading next image: /Users/kirkt/Desktop/E​nfuseTest/dxo6/_MG_001​0enfuse.tif 1/1

Kirk,

Yes, that does help and pretty much what I figured out but one thing I'm not understanding is the 'fill with black' part. Once you create an Alpha Channel and apply it to the image, doesn't it act like a layer mask blocking out the selected pixels automatically? If not, what steps are you taking to 'fill' with black?

Thanks!

To make the alpha, you have to go to the channels palette and create a new channel - it should be labeled Alpha 1 by default. This is where you place your black and white "mask". You can make your mask on a normal layer and then Select All, Copy, and then Paste the mask into the Alpha. Or, you can make the selection of what you want to mask in the normal layers view and then, with the selection active, switch to the Alpha channel and fill as usual. However you make your black and white mask, it is not a layer mask, it is an alpha channel.

Painting on an Alpha channel is the same as painting a regular layer mask. It does not need to be active or visible when you save the file (as a TIFF, or whatever) you just need to remember to check the "Alpha Channels" check box in the Save dialog to make sure it gets saved in the TIFF.

Kirk

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Thanks!