Removing white space

[sarah66]

I am wanting to know how to work with a piece of black and white line art to make the white transparent. The problem if I just simply select the white space, with a tolerance of, say 20, it leaves the "black" parts of the image still in greyscale. What I need to be able to do is convert that black-white gradient into a black-transparent gradient. So that there is a gradient of partial transparency that avoids harsh edges in the finished image. (The intention then is to convert it into an alpha channel).

The only online tutorials I can find talk about Photoshop and the techniques don't seem to work in PSP. How can I achieve this in PSP X?

[iamtheblues]

If you export the graphic as a portable network graphic file, you can select the white background as transparent in the options dialogue box.
Saludos,
Bob.

[steve.ledger]

Follwing on from Bobs suggestion.
PSP X2 uses the PNG Optimizer under Export.

Choose your export settings appropriate for your image.
Here I used the 'Areas that match this color' for transparency.

[sarah66]

I tried this, and it doesn't achieve the effect I need.

The image is not purely just black and white. The edges are anti-aliased and so there is a slight gradient at the edge, with some pixels in various shades of grey. Your technique takes out the ones that are pure white but leaves the grey ones grey. I need those grey pixels to be partially transparent. eg for a pixel that is 50% grey in the original, I need it to be 100% black but 50% transparent. That way, if I superimpose the line art over a background colour that is not white, there's no grey "halo" round the edge. If I raise the tolerance higher, it takes out some of those grey pixels altogether but I don;t want them removed, I need them to be still there but "faded", so the background colour will show through.

Does that make sense?

[steve.ledger]

You would then select 'Alpha channel transparency' instead.

[sarah66]

This is where I'm getting confused. How do I create an alpha channel from an image that's not currently got any transparency in it?

Can you go step by step? I currently have just the simple greyscale image, no layers, no alpha channel.

[molucca]

You could use the background eraser and set the erasing color to white. RGB 255,255,255

I don't know too much about psp, but it appears you need to premote to a full layer.

Rich

[Soquili]

Sarah to convert your image to a 2 colour black and white only image, use the Image menu > Decrease Color Depth > 2 Colors. Now the grays will be gone and you can remove the white and have only black remain.

NOTE:
Do not expect to have the smooth curves you see in the original line art because there will be no antialiasing. This is the way computer art works. Pixels on the screen and to a lesser extent dots on printed paper will have noticable "jaggies" when antialiasing is removed.

[steve.ledger]

II need those grey pixels to be partially transparent. eg for a pixel that is 50% grey in the original, I need it to be 100% black but 50% transparent. That way, if I superimpose the line art over a background colour that is not white, there's no grey "halo" round the edge.

If your background colour is anything but white, your 50% transparent edges will show 50% of the colour it sits on. Is this what you desire?

Maybe some 'easier to use software' might help here?
Xara Xtreme can simplify this process easily using 'Stained Glass' transparency. Your image can then sit ontop of any backround as shown in my attachment.
You can download a 30 day fully functional non-crippled trial version from Xara.com

Also check out the Fine Threshold filter from MEHDI (freeware). This will produce terrific black and white (2 colour) results from photos.

[molucca]

I got Mac White to work, but needed plugin.dll in the second plugin folder.

I tried to do this in XXP with BMT and contone recoloring. I started with a color image, and recolored. A few bitmap copies, and recoloring to all black pixels. Then making the black and white image transparent with the gray scale copy. Made PNG, and looked at the alpha channel in PS7. Since the alpha is gray, the transparency should correspond to the gray value.

I didn't get any of the other white filters to work, but this is on my old system and probably needs a few DLLs.

Rich