Background Special effects

Hello, is very common to find vfx sprites with a black background and lots of engines have a way to specify an alpha color, so all the black will be removed. Here is an example of an sprite sheet:

<img src="http://www.znelarts.com/cosas/explode_16.bmp" border="0" />

There is no way to remove the background with photoshop or any program without a loss in information, so how can I set Construct 2 to have an alpha colour to be trasparent??

You mean like this?

<img src="https://dl.dropboxusercontent.com/u/20459682/exp_alpha.png" border="0" />

Granted, that was only a 2 second job in PSP9 and needs a little touching up, but your image wouldn't work very well just doing the one black color because you'd end up with artifacts around the borders of the explosion images in each frame because of the aliasing/smoothing done around the images. Instead you'd go for a luminance mask, and then clean up the mask afterwards to give better color while not getting all that black outlining you'd normally get from just picking a color to be an alpha color. Unless that's the look you wanted to go for.

Yes, how you did that without loss?? I was using PS and removing the black with channel masks but I still lose info on the image.

Not sure how to do it exactly in PS, but in Paint Shop Pro 9 you can create a mask layer by the image source's luminance. The darker the color the more transparent it becomes. You would probably then want to edit the mask so the orange sections aren't as transparent.

I could have sworn there was a blend mode option in Construct 2 for this type of thing as well...

Select a sprite and in the Properties pane you have blend mode as well as effects that may be able to help here...