Removing alpha channels EXTREMELY time consuming

[soloman]

I'm removing the alpha channels from my game to make it run smoother on iOS .

Instead of creating a PNG with alpha, I created a BMP with a black background. I imported it to MMF2 then proceeded to remove the black outline from around the image. I did this 25 times and it took over 2 hours. There's over 600 of these to do for the entire game!

The images have different colors around the edges so I can't just choose a background color that's similar to the image.

Can photoshop or any other program do a crisp, non-bleeding 2 pixel choke like that used for green screen?

Does anyone know a sanity saving way to remove the background without leaving the ugly outline?

[soloman]

Anyone?

[DistantJ]

In photoshop you can make use of the "feather" option under select - modify to select an area and then smoothen out the edges of the selection, then maybe you could fill the selected areas in black, so that any anti-aliasing pixels are made to appear on black. You could potentially set it to automate too using photoshop's action recording, you just might have to manually select the bg each time then hit play.

[monkeytherat]

You could turn the tolerance on the fill tool down and try to make the outline all one color, the same as any blank space you have, then just fill the outer space transparent.

[Anders]

If you simply use the transparent color option in MMF2 you don't need to remove the alpha channels. MMF2 will be able to compress the images much better if you use that option.

[LB]

But when you change from Alpha Channel to Transparent Color in MMF2, everything that is not the transparent color becomes visible, and you still have the problem of trying to fix the outline by hand.

[soloman]

Thanks for the suggestions. Unfortunately they're not producing the desired results.

Surely there's a way. Google doesn't help as I don't know the terminology. There's got to be a name for what I'm wanting to do. That will be the key to finding the solution.

[AndyH]

Not sure if this is specifically the problem you are having, but when I convert images with an alpha channel to be used with a single indexed transparency colour for MMF I will load the original image (with alpha) in Photoshop, create a layer beneath it with the colour I want the semi-transparent areas to blend with (eg: black, white or what ever colour is the most proninent for the background of the game where the graphic will be used) and then flatten the layers in Photoshop. This tends to help reduce the amount of editing I have to later do to sort out the edges of the graphics. You can create a macro in photoshop to do this too, which saves on time.

Also, if your image contains areas that you want to blend with another colour, you would have to manually add this colour on the bottom layer in the areas affected before you flatten it.

What you are still left with though is if your edges blend are too 'thick' you will still need to reduce that, and in Photoshop there are a number of ways, none easy though. For example you could use the magic wand tool with a higher tolerance to select the 'transparent' areas of your image which would creep into the blended edges so you could delete/cut them out. I would be interested to know if there is an easier trick or filter to help with this too.

[DistantJ]

Nice idea Andy, that could be completely automated with photoshop's recording feature too since there's no specific selection, just create new layer, move layer to bottom, fill, flatten, save, close, move on to the next. Could get it to go through all your images instantly.

I've never had to remove my alpha channels, but then my games never tend to be dealing with a high number of objects on screen...

[life2searching]

hmm, this is very interesting thread to read as i consider getting the ios exporter, and many of my games assets have heavy alpha usage.

exactly how badly does having alphas affect performance?

what res are you working at?

what kind of sizes are the active objects that you are fixing