Gimp + Flaming Pear Solidify (or other 'blend alpha edges' filter)

[Romaq Rosher]

I'm following along with http://www.youtube.com/watch?v=N1AyEuB0b6M (Multi Chain Hax Part I video) and I would like to follow along with it. The Flaming Pear Solidify filter has a very nice effect, in my opinion, on blending the edges of an alpha channel and I wish to use that affect for various things I would wish to create. http://unity3d.com/support/documentation/Manual/HOWTO-alphamaps.html shows much the same thing with a built-in filter. The crucial goal is this: blend colors at the edges of an alpha shape into the background smoothly. Flaming Pear's Solidify is happy, but I'm game with 'whatever works' in Gimp.

I fetched the latest version of PSPI for the latest version of GIMP, and it appears to work as expected. I *can* use some of the Flaming Pear freebies, just not Solidify. The image is a .png plant with a transparancy layer. I have tried duplicating the layer and having only that layer selected, but I get the following error:

"This filter cannot operate on the image's background. Use it on a layer with transparent regions." I can click on the channels tab and see the RGBA. I made a new Alpha Channel Copy, selected and visible... the filter still responds with the error message. I've used Irfanview, set it up with the filters, some filters work. Solidify returns the very same error message even though Irfanview shows an alpha channel.

What's the trick to get FP Solidify to work in GIMP?

[Incony Hathaway]

i use jasc psp, and like you it often comes down to trial and error.. you try something after many steps... and it works.. but damn did you remember all the steps it took to reach?  no..

i know that doesnt give you a solution, i just share.. one has to be methodical.. write down everything you do to get from a to b..

there is no satnav to tell you... its map reading..

 

but yes.. i have and can create alpha using textures that can fade into nothing...  one must remember how sl uses either black..  or white.. as the background..  and as consequence, one must change the texture colours to enable that..  anything black.. is invisible.. the exact colour...  anything white is visible, the exact colour...  and the fade between the two, is every pixel colour between them.. 0 to 255...  a lot of pixels...  and every shade of colour in that too.. alpha is is an art , the picture you paint...

 

[Claire Harford]

If you haven't already visited my blog you might find the previous comments helpful for translating the video to GIMP.

Multi Chan Hax- It's all kinds of awesome!

Watch the video tutorial for using Multi Chan Hax up until it mentions the issue of the pixels stopping at the edge of the avatar mesh- then have a read through the following text. The Flaming Pear Solidify filter appears to be incompatible with the latest version of GIMP. The steps I’ve detailed below is as close as I can “translate” for now.

Duplicate the “texture” layer and rename the lower layer “texture bleed”.

Make sure you’re working on the “texture bleed” layer and go up to Filters >>> Blur >>> Blur. Duplicate this layer then merge the two “texture bleed” layers together. You might have to repeat the last two steps a few times (4-8 times depending on canvas size). So blur, duplicate, merge down, blur, duplicate, merge down and so on.

That is pretty much all the solidify filter does by the way- it just does it much more aggressively using a few different algorithms and it works a helluvalot faster for an entire canvas than having to do it manually. As far as I know- there is no equivalent filter for GIMP that does the same kind of job.

The process of blurring and merging down is a great tip for getting rid of the white halo effect in GIMP. Even with the “texture bleed” visibility turned off it should sample the colour from the layer beneath- but you want to leave it ON because we want more than just the 1 pixel anti-aliasing buffer. You want a decent and deliberate bleed area in this case. So after you’ve solved the dreaded “jaggies” and created a decent bleed area on the seams but you will still need to go in and manually clean up the upper edge to maintain any hard lines. So from here on you can just mask or erase what you don’t want to see.

One way to do it would be to select the “texture” layer in the layers palette, right click and from the list that drops down choose “Alpha to Selection”. This will give you the same “marching ants” selection as what you can see in the video. With this selection active go up to Select >>> Grow >>> 4 pixels.
Then switch back to your “texture bleed” layer, right click and select “Add Layer Mask”. A popup window will appear asking you what kind of mask you wish to create. Check the box for “Selection” then click the “Add” button. Now go up to Select >>> None (or control+shift+A) to deselect.

GIMP works as a “what you see is what you get” editor when it comes to see transparency. It doesn’t have the same kind of alpha “channels” as Photoshop does, rather, it makes use of the layers transparency instead. I’m tempted to call it “visible transparency” but that seems a bit redundant, a bit like the phrase “free gift” (haha- sidetracked! sorry!).

Moving along… all you need to do now is turn off all the layers you don’t want to see such as templates/backgrounds and leave your sock layers visible. If you can see the grey checkerboard where you want transparency- you’re good to go!

 

[Romaq Rosher]

Thank you everyone for your help. I'll muddle through the work arounds, but the Solidify filter is VERY nice, and I deeply regret we can no longer use it.