Hi there !

I have in my houdini file a COP2 network making some changes to textures on my hard-drive, and then outputting those textures with a ‘ROP File Output’ node.
Those textures are actually a set of Masks, each channel is a different mask (R=Metallic,G=AO,B=Emisside and A=Smoothness)

This is working nicely, but here is the issue:
Those outputted .tif files are using the alpha channel as transparency, and if I open them with Photoshop, there is no accessible alpha channel, and instead all my RGB channels are displayed with transparency.
Basically, I cannot use those textures as they are, they are completely impossible for an artist to author in Photoshop.

Is there any way to export/render a COP network into a tiff file, and keep a clear visible alpha channel, accessible in Photoshop ?

Edit: Mentionned tif and png, but png never supported alpha channel, only transparency.

Hi, not sure if this helps but if you use exr instead, Photoshop will ask if you want to keep transparency or alpha. (the latter seems to be what you're looking for)

Rob

Hi, thank you for you suggestion !
The context of my problem is that I would like to integrate houdini in a video game production pipleline environment, and for that .tiff and .png(easier to share source file due to compression) are the bests file formats nowadays.
The generated files will also be uploaded online later on, and .exr are way too heavy.

Photoshop is very rigid with how it interprets the alpha in RGBA images. It depends on the image spec how whether it is loaded as alpha or transparency. As a workaround you could separate your grayscale layers into separate files before opening in photoshop. You can use channel copy/delete COP to split the RGB from the alpha before writing out to your 8bit format of choice. Then you can use either photoshop or a COP network to recombine the individual grayscale images into a single RGBA image file.

This seems like a common problem when loading CG elements into photoshop:
http://forums.cgsociety.org/archive/index.php?t-1069810.html [forums.cgsociety.org]
https://feedback.photoshop.com/photoshop_family/topics/import_optionf_for_rgba_files_to_interpret_alpha_as_layer_mask_or_transparency [feedback.photoshop.com]

Another option could be to output exr from Houdini and use actions/batch/image processor in Photoshop to save as tiff. (I haven't tried it but it should work in theory)

In Photoshop You can convert transparency into alpha by using Layer/Layer Mask/From Transparency and then copy Layer mask into alpha channel.

I've attached atn file with fancy action that does this

So, to bump this thread again. Everyone responded with exporting EXR and converting in Photoshop, or something similar…but no one had an answer for Exporting a tif from Houdini with an alpha channel? Why is this not possible?

It works with good old TGA, which are suitable for a game pipeline

Just make sure you have the alpha premultiplication turned off - https://www.sidefx.com/forum/topic/57642/?page=1#post-267193 [www.sidefx.com]